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Breeding biology during establishment of a reintroduced Griffon Vulture Gyps fulvus population
Abstract
We studied the breeding parameters of a reintroduced population of individually marked Griffon Vultures Gyps fulvus in the Grand Causses region of southern France from the time of first reintroduction in 1982 to 1992. Among nesters, 65% of the birds released as immatures or born in the wild recruited into the breeding population when 4 years old, i.e. 1 year earlier than previously described. The proportion of birds nesting each year was relatively high and increased with time, suggesting that conspecific attraction favoured recruitment. We detected a permanent adverse effect of long-term captivity on the nesting success of birds released when more than 2 years old: compared to the natural population, birds which had been kept in captivity showed a reduced breeding success during the whole study period. The breeding success of released immatures and wild-born birds was similar to the highest values observed in a natural population in the Spanish and French Pyrenees. Breeding failures did not usually result in mate change but affected nest-site fidelity. Birds not born in the wild were more likely to recruit to the largest subcolonies available, which highlights the role of social attraction. The observed philopatry of wild-born birds probably resulted from such a social attraction since most of them were born in the largest subcolony. Conspecific attraction maintained the spatial aggregation of nests, whereas nest changes after a breeding failure favoured the spatial expansion of the colony.
... The accepted definition of a colony is: a place where several pairs nest at a centralized location, from which they recurrently depart in search of food (Wittenberger & Hunt 1985). Several authors (Sarrazin et al. 1996, following by, for example Del Moral & Marti 2001, Lopez-Lopez et al. 2004, Zuberogoitia et al. 2009, Del Moral 2009, Xirouchakis & Mylonas 2010, Zuberogoitia et al. 2011, Demerdzhiev et al. 2014, Zuberogoitia et al. 2019 agree that a Griffon's nesting cliff is considered a colony when it is occupied by at least two pairs, at a distance of at least 1000 m from the neighbouring occupied cliff, whilst isolated pairs are those that breed on their own, more than 1000 m from the nearest colony. ...
... All breeding parameters were calculated for all nest-clusters on the island of Cres and two nest-clusters on the island of Plavnik, during the period of 10 years (1995 -2004). The chicks that disappeared after 100 days of age were considered to have fledged, even if later found drowned, as any deaths after that date affected the first-year survival rather than the breeding success or the productivity (Sarrazin et al. 1996). Population density was calculated as the number of individuals and breeding pairs on the possible foraging area, excluding human settlements (in 100 km 2 ). ...
... The average breeding success on Cres/Plavnik in a ten-year period (1995 -2004) was Bs = 0.60 ± 0.059 (mean ± SD), varying from 0.51 to 0.69. Comparing the breeding success of the Kvarner nest-clusters with other European colonies, it was lower than in any other country: Serbia (0.81), Portugal (0.69), the French Alps (0.7), Bulgaria (0.77), Crete (0.74), Cyprus (0.74), the French Pyrenees (0.76), Spanish Pyrenees (0.77), and Sardinia (0.77) (Leconte 1985;Sarrazin et al. 1996;López-López et al. 2004;Iezekiel et al. 2004;Aresu & Schenk 2005;Terrasse 2006;Beest et al. 2008;Del Moral 2009;Xirouchakis 2010;Demerdzhiev et al. 2014;Marinković et al. 2020). This variation in the breeding success among areas might be explained by differences in food availability, intra-specific competition (density of breeding pairs), or climate (Beest et. ...
The Eurasian Griffon population in Croatia declined during most of the 20 th century. Here the results related to the population trend and reproduction parameters and phenomena called colony shifting based on a 40-year research (1981-2021) are presented. The population declined from about 110-150 pairs in 10 colonies in 1981 to 78-95 pairs in 6 colonies in 1999, and subsequently increased to 141-150 pairs in 6 colonies in 2013. Since 1999, there have been no Griffons nesting in Paklenica, and it is possible that they all shifted to Kvarner, where 13% increase was recorded in 2000. In 2021, the total number was about 120 pairs on 5 islands: Cres, Plavnik, Krk, Prvić and Pag. Population density was estimated at 32.5 adult individuals/100 km 2 and 13.75 breeding pairs/100 km 2. Detailed population surveys were conducted during 15 years (2000-2014) to document cliffs' saturation/occupancy, inter-and intra-colony nest movements, and for 10 years, to calculate reproductive parameters: breeding success Bs = 0.60 ± 0.059 and productivity Pd = 0.55 ± 0.054. The nest site occupation was very low (M = 15.05%), implying that carrying capacity was not determined by cliff availability, and population is still far from saturation level. Six Kvarner islands' colonies are functionally one single colony with many nest-clusters on the same or on different 21 LARUS Vol. 56, 2021 islands, annually pulsating with numbers of active nests on cliffs and regularly shifting from cliff to cliff and back.
... Specie monogama, con forte fedeltà di coppia (es. Sarrazin et al., 1996), in cui entrambi i sessi partecipano alla costruzione del nido, alla cova e all'allevamento della nidiata. L'età della prima riproduzione è intorno al 4°-5° anno. ...
... L'età della prima riproduzione è intorno al 4°-5° anno. La mancanza di casi di riproduzione da parte di giovani di età inferiore ai 4 anni sembra confermare che la maturità fisiologica potrebbe essere raggiunta a questa età (Sarrazin et al., 1996). La deposizione dell'unico uovo avviene tra gennaio e marzo, a volte ad aprile. ...
... Si sono ottenuti 4 diversi scenari: Scenario pessimistico nell'area compresa da 2 parchi: si ha una probabilità di estinzione del 50% sui 100 anni. (Sarrazin et al., 1996); età massima di riproduzione: 20 anni (Pavokovic & Susic, 2005); sex ratio alla nascita: 50% (Pavokovic & Susic, 2005;Bosé et al., 2007); percentuale di femmine adulte che si riproducono con successo: 60% (Pavokovic & Susic, 2005); produttività (n° di giovani involati/coppie riproduttive): 0,50 (per precauzione si è considerato un valore basso, stimato in base ai lavori di e di ); massimo numero di progenie per anno: 1; tasso di mortalità per classi di età, per entrambi i sessi: 10% nei giovani di età inferiore ai 3 anni e 1% negli adulti e nei giovani di età superiore ai 3 anni ; capacità portante (stimata in base alle potenzialità trofiche dell'area compresa dal Parco del Gran Sasso e Monti della Laga e dal Parco dei Monti Sibillini e prevedendo anche la realizzazione di carnai): 350 individui. ...
Analisi di fattibilità per la reintroduzione del Gipeto (Gypaetus barbatus) ed il ripopolamento del Grifone (Gyps fulvus) nell’Appennino centrale.
Il documento è stato redatto secondo quanto previsto dalla Direzione Protezione della Natura del Ministero dell’Ambiente e dalla Tutela del Territorio e del Mare e dall’Istituto Superiore per la Ricerca e Protezione Ambientale ISPRA.
Queste alcune delle conclusioni dell’analisi:
- E’ stata accertata la presenza storica del Gipeto nell’Appennino centrale. Per quanto riguarda il Grifone la specie è già presente nell’area grazie ad un’azione di reintroduzione effettuata dal Corpo Forestale nella Riserva Naturale dello Stato del Monte Velino.
- Il territorio compreso nel Parco Nazionale dei Monti Sibillini e nel Parco Nazionale del Gran Sasso e Monti della Laga è idoneo a sostenere una minima popolazione vitale di Grifone calcolata in almeno 50 individui. Il Gipeto potrebbe formare 6 coppie potenziali all’interno dei due parchi ma il numero sarebbe al di sotto di quello necessario per sostenere una minima popolazione vitale, calcolata in almeno 10 coppie. Per questo motivo è necessario estendere il progetto di reintroduzione del Gipeto alle altre aree protette presenti nell’Appennino centrale al fine di costituire una popolazione potenziale di almeno 13 coppie.
- Si ritiene imprescindibile che vengano attuate, in tutto l’Appennino centrale, misure efficaci contro l’uso di bocconi avvelenati.
- L’eventuale espansione incontrollata di impianti eolici industriali all’esterno dei parchi dell’Appennino centrale o di impianti minieolici (di grandi dimensioni) anche all’interno dei parchi potrebbe compromettere del tutto qualsiasi tentativo di riportare il Gipeto nell’area e di incrementare la presenza del Grifone.
... In animals, non-genetic issues are associated with captive-rearing and release strategies, leading to various factors potentially affecting demographic rates in the wild. These include individual condition, such as health status, physiology and behaviour (Champagnon et al. 2012;Dickens et al. 2010;Hardouin et al. 2014;Tavecchia et al. 2009), proximity of the release site with other populations (Mihoub et al. 2011), period of release (Hardouin et al. 2014), age at release (Sarrazin et al. 1996) or the size and composition of the animal group (Hardouin et al. 2014(Hardouin et al. , 2015a. Additionally, the potential impairment of demographic performances of translocated individuals might be explained by the interaction of their phenotype with their new environment and release conditions. ...
... Such effects can be estimated either by assessing changes in vital rates over time in a release cohort (e.g., Armstrong and Ewen 2001;Tavecchia et al. 2009) or by comparing vital rates of translocated and resident animals over the same time period (e.g., Brown et al. 2006). A number of studies in translocated vertebrates have documented these post-release effects, mostly in terms of survival probabilities (Armstrong et al. 2017;Bertolero and Oro 2009;Hardouin et al. 2014;Sarrazin et al. 1994) but also in reproduction rates (Bertolero and Oro 2009;Converse et al. 2013;Sarrazin et al. 1996;Tavecchia et al. 2009) and even in dispersal behaviour (Le Gouar et al. 2008;Mihoub et al. 2011). In the particular cases of translocated individuals originating from captivebreeding, any impairments of vital rates in translocated individuals can result either from translocation conditions (i.e., post-release effects per se), captivity conditions (including genetic and non-genetic issues), or the interaction of translocation and captivity conditions. ...
... Conversely to our expectations, we did not observe any interaction between the age of the female and its origin. This result is consistent with the long lasting (i.e., permanent) negative post release effect on breeding parameters observed in other translocated species (see, e.g., Sarrazin et al. 1996). It is also consistent with previous findings in Houbara that released captive-bred females exhibit age-dependent patterns of variation in breeding performance, similar to those observed in many vertebrate populations in the wild (i.e., a bellshaped trend divided into youth, adulthood and senescence; see discussion in Bacon et al. 2017a). ...
The success of translocation programmes is reflected by the ability of translocated individuals to survive and reproduce in their new environment. However, it has previously been reported that translocated individuals have lower demographic performance than their wild-born conspecifics, due to management and individual factors (such as release conditions or age). Here, we study six breeding parameters in free-ranging females of the North African Houbara bustard (Chlamydotis undulata undulata) and compare these parameters between captive-bred released (n = 204) and wild-born (n = 101) birds, considering the age of individuals and the period of release (autumn versus spring). Our results indicate that (1) captive-bred released females successfully breed in the wild; (2) for three out of the six breeding parameters studied, released females show lower performances than wild-born females; but, (3) Although we observed consistently reduced breeding performances in 1 year old females relative to older females, we did not uncover any interaction between age and the origin of females, suggesting that the impairment of breeding parameters in released females is long lasting; and, (4) interestingly, this impairment of breeding parameters depends on the period of release, with lower breeding performances for spring releases compared to autumn releases. Overall, our study highlights the capacity of captive-bred females to reproduce in the wild, contributing to the dynamics of the population beyond their individual history. Our results also uncover complex variations of breeding parameters in translocated birds, but suggest that these differences can be minimized through an appropriate translocation strategy.
... This requires reliable information about dispersal. Previous re-introductions have often been poorly managed, and there is a lack of scientific follow-up studies to learn from mistakes, improve methods, and detail dispersal behaviour (Sarrazin and Barbault 1996). Settlement behaviour in particular can be critical to success and can be directly assisted if understood (Sarrazin et al. 1996). ...
... Previous re-introductions have often been poorly managed, and there is a lack of scientific follow-up studies to learn from mistakes, improve methods, and detail dispersal behaviour (Sarrazin and Barbault 1996). Settlement behaviour in particular can be critical to success and can be directly assisted if understood (Sarrazin et al. 1996). Introduction experiments offer a controlled environment in which to identify key features of settlement behaviour (Massot et al. 1994b); however, the conditions of departure from the original territory and of the transient stage during dispersal are far harder to investigate. ...
... Introduction experiments offer a controlled environment in which to identify key features of settlement behaviour (Massot et al. 1994b); however, the conditions of departure from the original territory and of the transient stage during dispersal are far harder to investigate. Nevertheless, conservation programmes could be doing more to establish specific hypothesis-testing research as part of their reintroduction schemes in order to answer questions about, among other things, dispersal (Sarrazin and Barbault 1996). There are of course many ways in which knowledge of dispersal might potentially be applied to practical action in conservation. ...
Dispersal is a fundamental parameter of population processes. In small and isolated populations, linked only when individuals are able to disperse between them, it becomes a particularly critical one which ultimately determines whether a species will become extinct. Predictions for these populations are limited because estimates of dispersal variables from the field are difficult to obtain and therefore scarce. Models are therefore also limited because they cannot be parameterized accurately, and have until recently ignored behavioural and spatial variation in dispersal. This problem is compounded for endangered species which most desperately need accurate viability analyses and management plans, but about which little is usually known and opportunities for research may be few. Threatened populations are not the only conservation application for dispersal. Predators and pests are a significant conservation concern, and advances in the management of these populations also require detailed understanding of dispersal behaviour to forecast their expansions. More detailed behavioural research into dispersal is clearly needed. Aside from their academic merit, the chapters within this book provide an excellent basis for furthering the application of research on dispersal to conservation biology.
... Variation in productivity is usually included in simulation models but variation in the age of first breeding is largely ignored in PVAs (Antor et al., 2007;Bretagnolle, Inchausti, Seguin, & Thibault, 2004;Evans et al., 2009;Margalida, 2017;Margalida, Colomer, Oro, Arlettaz, & Donázar, 2015;Naveda-Rodríguez, Vargas, Kohn, & Zapata-Ríos, 2016;Radovic & Mikuska, 2009). Nevertheless, in most reintroduction programs a lower than expected age of first breeding was reported (Evans et al., 1999(Evans et al., , 2009Muriel, Ferrer, Casado, Madero, & Calabiug, 2011;Muriel, Ferrer, Casado, & Pérez Calabuig, 2010;Sarrazin, Bagnolinp, Pinna, & Danchin, 1996;Woods et al., 2007) showing that age of first breeding decreases as predicted in a low-density situation. ...
... Reduced age of first breeding is commonly reported from reintroduction projects (Monti et al., 2014;Sarrazin et al., 1996) and acts as a buffer against extinction in small and colonizing populations (Ferrer et al., 2004). In long-lived territorial raptors, entry to the breeding sector has also been found to bring about a reduction in the probability of mortality. ...
• The present biodiversity crisis has led to an increasing number of reintroduction programs, and this conservation method is likely to be increasingly used in the future, especially in the face of climate change. Many fundamental questions in population ecology are focused on the mechanisms through which populations escape extinction.
• Population viability analysis (PVA) is the most common procedure for analyzing extinction risk. In the use of PVA to model the trajectories of reintroduced populations, demographic values are sometimes taken from other existing wild populations or even from individuals in captivity.
• Density dependence in productivity is usually considered in viability models, but density‐dependent variation in age of first breeding is usually ignored. Nevertheless, age of first breeding has a buffering effect on population fluctuations and in consequence on population persistence.
• We simulated the viability of Spanish Imperial Eagle (Aquila adalberti) and Osprey (Pandion haliaetus) populations using data from established and reintroduced populations in southern Spain.
• Our results show that reduction in the age of first breeding is critical in the success of reintroductions of such long‐lived birds. Additionally, increases in productivity allow populations to growth at maximum rate. However, without considering variation in age of breeding, and the associated increasing overall productivity, reintroduced populations seem nonviable.
• To ignore density dependence in age of breeding in PVA means that we are seriously limiting the potential of the model population to respond to fluctuations in density, thereby reducing its resilience and viability. Variation in age of first breeding is an important factor that must be considered and included in any simulation model involving long‐lived birds with deferred maturity.
... Conservation translocations are increasingly used to manage threatened species and to maintain or establish viable populations in the long term (Armstrong and Seddon, 2008). Translocated populations are likely to suffer demographic costs in terms of survival (Hardouin et al., 2014) and reproduction (Sarrazin et al., 1996), especially in translocations relying on captive breeding (Robert, 2009). Thorough assessments of these demographic costs and of their potential effects on the life history of released individuals are nevertheless rarely done, because they require high quality demographic data, which are generally lacking due to insufficient monitoring effort (Bertolero et al., 2007). ...
... More technically, statistical inference of senescence patterns in the wild requires large, individual-based longitudinal datasets, which have become available only recently (Nussey et al., 2008). The assessment of senescence patterns in translocated populations is especially challenging because (1) sample sizes are generally low; (2) accurate long-term demographic monitoring is generally lacking; (3) in several taxa, translocated individuals have been shown to suffer demographic costs of survival and/or breeding parameters (Sarrazin et al., 1996;Hardouin et al., 2014), which may complicate the assessment of agedependent breeding parameters and further reduce the probability that individuals reach senescent ages. ...
In free-ranging populations, age-dependent variation in fitness related parameters, in particular the pattern of senescence, has major eco-evolutionary implications and potential influence on population dynamics. Despite the recent surge of studies of senescence in the wild, senescence patterns in species for which population dynamics assessments are crucial, such as translocated populations, remain virtually unexplored. Based on a 15-year nest survey of a North-African Houbara bustard population in Morocco, we investigated age variation in the breeding performance of captive-bred females released in the wild. We identified 781 females, from 1 to 10 years of age, on 1094 nests. We examined how age influenced nest initiation date, clutch size, egg volume, daily nest survival and daily brood survival, as well as whether age-dependent patterns varied according to environmental conditions. Most breeding parameters exhibited variation, suggesting an increase in breeding performance with age in young females (those from 1 to 3 years old). In older females (> 7–8 years old), the egg volume and clutch size decreased with age, in concordance with expectations from senescence theories and previous empirical results obtained from captive Houbara bustards. Finally, our analysis uncovered a significant interaction between age and the amount of precipitation prior to the breeding season on clutch size, suggesting differential abilities of females of different ages to increase their breeding investment. Our study suggests that life histories in translocated individuals are not affected by translocation protocols and provides insights for implementing age dependencies in population viability assessments.
... They become sexually mature at 4 years; females lay one egg per year. Griffon vultures are generally philopatric, with breeders being faithful to their area of first breeding (Sarrazin et al. 1996). Nevertheless, erratic behavior of young birds is frequent (Bernis 1983). ...
... The demography of native and reintroduced Griffon vulture populations has been intensively monitored since 1970. Such surveys have provided valuable information regarding survival (Sarrazin et al. 1994), breeding biology (Sarrazin et al. 1996; Fernandez et al. 1998 ), and movement (Susic 2000, Bosé et al. (in press)). However, they are not sufficient to infer some important demographic processes, such as effective dispersal. ...
It is generally considered that limiting the loss of genetic diversity in reintroduced populations is essential to optimize the chances of success of population restoration. Indeed, to counter founder effect in a reintroduced population we should maximize the genetic variability within the founding group but also take into account networks of natural populations in the choice of the reintroduction area. However, assessment of relevant reintroduction strategies requires long-term post-release genetic monitoring. In this study, we analyzed genetic data from a network of native and reintroduced Griffon vulture (Gyps fulvus) populations successfully restored in Southern Europe. Using microsatellite markers, we characterized the level of genetic diversity and degree of genetic structure within and among three native colonies, four captive founding groups and one long-term monitored reintroduced population. We also used Bayesian assignment analysis to examine recent genetic connections between the reintroduced population and the other populations. We aimed to assess the level of fragmentation among native populations, the effectiveness of random choice of founders to retain genetic variability of the species, the loss of genetic diversity in the reintroduced population and the effect of gene flow on this founder effect. Our results indicate that genetic diversity was similar in all populations but we detected signs of recent isolation for one native population. The reintroduced population showed a high immigration rate that limited loss of genetic diversity. Genetic investigations performed in native populations and post-released genetic monitoring have direct implications for founder choice and release design.
... Several studies have also directly assessed the differences between captive and wild stock by comparing post-release survival of individuals of the same species translocated in similar circumstances. Captive-reared northern water snakes (Nerodia sipedon sipedon) show reduced survival relative to wild snakes (Roe et al., 2010) as do galliformes (Sokos et al., 2008), Aplomado falcons (Falco femoralis septentrionalis) (Brown et al., 2006), otters (Lutra lutra) (Sjoasen, 1996), Vancouver Island marmots (Marmota vancouverensis) (Aaltonen et al., 2009) and griffon vultures (Gyps fulvus fulvus) (Sarrazin et al., 1996). In contrast, Santos et al. (2009) found no difference in captive-bred versus wild lacertid lizards (Psammodromus algirus) and Tweed et al. (2003) attained an impressive 100% survival to 56 days for captive-reared puaiohi, a Hawaiian bird (Myadestes palmeri). ...
... We also note that in the examples cited above, while captive-reared individuals fared worse than their wild counterparts, success could be improved by varying release strategies. For example, in Vancouver Island marmots individuals released at two years of age survived better than those released at one year (Aaltonen et al., 2009), griffon vultures released as immatures had greater breeding success than those released at two years of age (Sarrazin et al., 1996) and otters released soon after separation from their mothers survived better than those held for longer periods in captivity (Sjoasen, 1996). Jule et al. (2008) note that the generally poor success of captive-reared animals has to be traded off against the ability and cost of rearing animals for release relative to sourcing animals from wild populations -particularly those of endangered species. ...
... In accordance with some other surveys (sarrazin et al. 1996, DeL moraL, marti 2001, Lopez-Lopez et al. 2004, DeL moraL 2009), a cliff was considered as a Griffon Vulture colony when it was occupied by at least two pairs, at a distance of at least one kilometer from the neighboring occupied cliff. The pairs that occupy nests situated at a distance of more than 1 km from a neighboring pair or colony were considered isolated pairs. ...
... The mean breeding success recorded in our survey (0.77) is above the average for Europe, being higher than that in Massif Central, France (reintroduced population) (0.57); Croatia (0.6); Macedonia (0.66); Spain (0.67); Northeast Portugal (0.69); French Alps (0.7); Crete island, Greece (0.74); and Cyprus (0.74) (sarrazin et al. 1996, Grubač 1997, Pavokovič, SuSič 2006, terrasse 2006, van Beest et al. 2008, DeL moraL 2009, XirouChakis 2010, but lower than that in Serbia (0.89) (Marincovič, orlandič 1994). Breeding success, very simillar or the same as in Bulgaria, was registered in French Pyrenees (0.76), Spanish Pyrenees (0.77), and Sardinia (0.77) (arroyo et al. 1990, LeConte, som 1996, aresu, sChenk 2005. ...
The Griffon Vulture in Bulgaria declined during the first half of the 20th century, from widespread and
abundant to localised and very rare. In the 1970s the species was on the brink of extinction, represented
by probably few scattered pairs in northeastern Bulgaria and less than 10 pairs in the south of Bulgaria,
where one population, common to Bulgaria and Greece, survived in the Eastern Rhodope Mountains. Here
we report the results of a 25-year long survey (1987-2011), which documents the steady increase in the
population from 10 pairs distributed in 2 colonies, to 56 pairs in 7 colonies. During the study period, 450
juveniles fledged from totally 646 occupied nests, with mean breeding success of 0.77±0.14 and mean productivity
of 0.71±0.16, indicating average values for Europe. The main limiting factor is the mortality after
consumption of illegally set poisoned baits, targeted against carnivores, followed by shooting, collision
and exhaustion. The human-wildlife conflict in large areas and the increasing illegal use of poison baits in
Greece are extremely hard to handle with. As a main conservation action for managing the Griffon Vultures
we recommend the implementation of large-scale diverse public awareness campaign targeted at schools,
kindergartens, governmental institutions, stock breeders, hunters and local communities.
... In the reintroduction of Griffon Vulture (Gyps fulvus), the breeding participation age was older in released birds than wild-born birds, probably because of a lower chance of finding a high-quality habitat using conspecific attraction (Sarrazin et al. 1996). This difference was not found in the reintroduced Oriental Stork. ...
Long-lived territorial bird populations often consist of a few territorial breeding adults and many nonbreeding individuals. Some populations are threatened by anthropogenic activities, because of human conflicts for high-quality breeding habitat. Therefore, habitat restoration projects have been widely implemented to improve avian population status. In conjunction with habitat restoration, conservation translocations have been increasingly implemented. Adequate nonbreeder survival can be a key factor in the success of these attempts because nonbreeding birds may represent reservoirs for the replacement of breeders. The maintenance of breeding pair numbers is also influenced by the transition rate of nonbreeders to breeders. The reintroduction of Oriental Stork (Ciconia boyciana), a long-lived, territorial, endangered species, was initiated in Japan in 2005 using captive birds in hopes of increasing the population’s use of restored habitat. Our objective of this study was to elucidate the factors determining reintroduced stork survival and recruitment to the breeding populations. We estimated the survival rate and breeding participation rate by sex, age, generation, wild-born or not, haplotypes, and breeding status in storks reintroduced during 2005–2022 using Bayesian hierarchical models. There was no significant difference in survival rate between nonbreeders and breeders. However, the survival rate was lower in wild-born birds than released birds, which may be related to the longer-distance natal dispersal of new generations. Accelerated habitat restoration around breeding areas and preventive measures for collision with human-built structures should be implemented for the sustained growth of reintroduced populations. A low survival rate was also detected for a specific mitochondrial DNA (mtDNA) haplotype that accounts for the majority of the reintroduced population. This phenomenon might be explained by mtDNA-encoded mutations. Moreover, captive breeding and release history might contribute to an increase in the proportion of this haplotype in the wild.
... For reinforcements involving animals bred in captivity, a common phenomenon is that captive-bred individuals survive at lower rates than their wild-born conspecifics (Aaltonen et al., 2009;Bertolero et al., 2018;Evans et al., 2009;Sarrazin et al., 1996). Differences in demographic performance may arise as a result of both genetic differences between captive-bred and wild-born animals (e.g. ...
... 2). This could be achieved by taking advantage of the species' high gregariousness and conspecific attraction (Mihoub et al., 2011), which has shown to be the main driver for the creation of new colonies (Sarrazin et al., 1996;Le Gouar et al., 2008). By supplementary feeding close to old traditional breeding or roosting cliffs, these sites would facilitate potential breeders to locate mates as well as providing safe, non-contaminated food (Bijleveld et al., 2010;Mateo-Tomás and Olea, 2010). ...
Vultures are among the most threatened avian taxa in the world. When vultures aggregate in large numbers to feed, poisoned carcasses can extirpate entire populations at once. In the light of shrinking numbers worldwide, restocking and reintroduction projects, where wild or captive-bred vultures are released back into nature, constitute a crucial management tool, successfully implemented in many countries. However, reestablishment of sustainable vulture populations to their historical ranges remains a serious challenge, especially if the threat of poisoning persists, which is usually the case. In this study, we model the outcome of a restocking project where an initial colony is subject to repeated poisoning events. We use as an example the isolated population of the griffon vulture (Gyps fulvus) in Cyprus. Mathematical considerations and model simulations show that the probability of colony persistence depends on the initial population size and the intensity and frequency of the poisoning incidents. This type of scenario creates an Allee effect that requires a colony to exceed a minimum size in order to survive. Also in this scenario, a sequence of small but frequent poisoning episodes is worse on average than a few large and rare ones of the same cumulative mortality. Future population reinforcement efforts for vultures should focus on the release of adult birds in adequate numbers for the successful establishment of sustainable colonies and should involve a reduction in small but persistent sources of mortality such as the poison baiting of small canids that until now has been neglected by conservation scientists.
... However, this has changed since the turn of the millennium with reintroductions being the focus of various studies including monitoring (Wakamiya and Roy 2009;Bernardo et al. 2011;Nichols and Armstrong 2012), management (Jones and Merton 2012;West et al. 2017), range expansion (Halley et al. 2012;Gaywood 2018) and population modelling (for summary see Armstrong and Reynolds 2012). The primary measure of the success of reintroductions is generally considered to be the establishment and successful breeding of a population and typically this is monitored for just a few years or until the emergence of the F1 or F2 generation (Wauters et al. 1997;Spalton et al. 1999; Richards and Short 2003;Sarrazin et al. 2008;Godefroid et al. 2011;Sanz and Grajal 2010). ...
The Marsh Fritillary butterfly (Euphydryas aurinia) is a Eurasian species which has suffered significant reductions in occurrence and abundance over the past century, particularly across the western side of its range, due to agricultural intensification and habitat loss. This loss has been particularly severe in the UK with extensive localised extinctions. Following sympathetic management, reintroduction was undertaken at four Cumbria (northern UK) sites in 2007 with stock from a captive admixture population descended from Cumbrian and Scottish founders. Annual population monitoring of the reintroductions was undertaken. Nine years post-reintroduction, the level of population genetic variation was assessed using microsatellites. Variation in historical Cumbrian samples was determined using museum samples and Scottish samples from current populations were assayed to characterise natural population variation. Half of the Scottish sites also served as indicators of the alleles present in the founder populations. The genetic contribution of the founder populations allied to population size data allowed patterns of genetic variation to be modelled. Alleles from Cumbrian and Scottish founders are present in the reintroduced populations. The four sites have levels of variation akin to natural populations and exhibit differentiation as predicted by statistical modelling and comparable with natural populations. This suggests that reintroduction following captive breeding can produce self-sustaining populations with natural levels of genetic diversity. These populations appear to be undergoing the same evolutionary dynamics with bottlenecks and drift as natural populations.
Implications for insect conservation
Reintroduction of captive bred individuals is a viable strategy for producing populations with natural levels of genetic diversity and evolutionary dynamics. Hybridisation of populations on the brink of extinction with those thriving can preserve some of the genetic distinctiveness of the declining population.
... Това налага, в районите обитавани от лешояди, да се изграждат площадки за подхранване, на които се изнасят труповете на умрели селскостопански и диви животни съгласно приетите санитарни изисквания (Oro et al. 2008, Mateo-Tomas et al. 2019. Осигуряването на достъпна за лешоядите храна на специално изградени за целта площадки за подхранване е природозащитен инструмент, чрез който се осигурява безопасна храна в райони, в които тя е оскъдна като по този начин се подпомага заемането на гнездови находища от които видът е изчезнал (Meretsky & Mannan 1999), подпомагат се програми за реинтродукция (Sarrazin et al. 1996, Terrasse et al. 1994, цели се увеличаване на преживяемостта на лешоядите (Piper et al. 1999, Lieury et al. 2015, Margalida et al. 2014) или повишаване на гнездовия успех на хищните птици (Gonzalez et al. 2016). Според редица автори съществуването на площадки за подхранване оказва и негативен ефект върху някои мършоядни видове птици като променя естественото им поведение за търсене на храна (Cortes-Avizanda et al. 2016, Piper 2014). ...
Animal movements and bird migration have always fascinated humans (Holyoak et al. 2008). With the fast technology advancement in the past 20 years new systems and methods were developed allowing animals to be tracked for longer periods and significant amount of data to be collected, stored and analysed (Cooke et al. 2004, Cagnacci et al. 2010). Vultures are obligate scavengers which consume up to 90% of the carcasses in some ecosystems providing significant ecosystem services. By efficiently disposing the carcasses they prevent the spread of diseases and save costs from transportation and incineration of animal carcasses (Houston 1986, Pain et al. 2003). However, vulture populations are experiencing dramatic declines worldwide and their conservation is a priority in many areas (Botha et al. 2017). Due to their conservation status and role in the ecosystems more studies on vulture movements and ecology are needed to inform efficient conservation strategies. The recent study was conducted on the autochthonous Griffon Vulture population in the Eastern Rhodopes, Bulgaria. In the period 2016 – 2019 we equipped with solar-powered GSM-GPS and Argos-GPS transmitters adult (n = 10), immature (n = 8) and juvenile (n = 7) Griffon Vultures in order to study their home range, movements, foraging behaviour and migration pattern. The foraging home range of the species was 2958.4 km2 (95% KDE) with core area of 231.6 km2 (50% KDE). Foraging home range size was maximal in summer and minimal in winter (3166.2 km2 and 1327.7 km2 respectively). Adult vultures had significantly smaller core areas compared to immatures (Z = –2.15, p = 0.03). The daily travel distance with all seasons and all individuals pooled was 79.1 ± 64.9 km while displacement was 21.4 ± 20.5 km. The longest daily distance was recorded on 07th May when an immature vulture travelled 364.4 km within the Eastern Rhodopes. Successful breeders travelled longer daily distances than the adults which were not breeding or failed at different stage of their breeding attempt (89.5 ± 71.9 km and 65.7 ± 65.9 km respectively, t = 4.37, p < 0.05). The mean daily distance travelled by the immature vultures was 85 ± 66.06 km while adults travelled 76.82 ± 64.5 km (t = –6.05, p < 0.01). The difference between the two age classes was most prominent during winter and autumn when immatures travelled 45.8 ± 41.7 km and 51 ± 44 km respectively while adults had significantly shorter daily distances 29.9 ± 31.3 km and 36.6 ± 42.8 km (t = –5.37, p < 0.01; t = –5.45, p < 0.01). Griffon Vultures were roosting mostly on cliffs (85.62%, n = 8120), in 14.05% of the cases they were roosting on trees and twice ground roosts were recorded. In the Bulgarian part of the Eastern Rhodopes vultures were roosting on cliffs in 94.6 ± 3.9% of the cases while in the Greek part of the mountain they were roosting mostly on trees – 78.7 ± 24.4%. Our results indicated high variance in the preferences of roosting cliffs according to the season. In autumn and winter vultures were roosting on cliffs with breeding pairs in 80.1 ± 24.2% and 88 ± 24.8% of the cases respectively while this percentage dropped significantly is spring and summer when vultures preferred to roost on cliffs with no breeding pairs (59.4 ± 25.3% and 45.8 ± 24.8%). The recent study showed that 71.5% of the juvenile Griffon Vultures migrate south in their first autumn while only 14% of the immatures started migration and none of the tracked adults. We followed 8 vultures during autumn migration and 5 during the spring migration. Autumn migration started in the period 19th September – 29th October. The average distance travelled on migration was 3602 ± 1137 km, covered for 38 ± 12 days with an average 44 migration speed 100.7 ± 32 km/day. The longest daily distances travelled on migration was 374 km on 30th October when the juvenile vulture 6G crossed the Bosphorus and reached the region of Gerede in Turkey. Spring migration started in the period 22th March – 7th May. The mean distance travelled was 2340 ± 737 km and migration took on average 13 ± 6 days with an average migration speed 176.3 ± 61.8 km/day. Griffon vultures had greater migration speed during the spring than the autumn (t = 2.50, p < 0.05). During autumn migration vultures used different stopover sites along the flyway where they spent between 3 and 50 days. The majority of the stopover sites were in Turkey, one was in Iraq and one on the border area between Iraq and Iran. All vultures followed the Eastern Mediterranean flyway through Turkey and Middle East. The most important bottlenecks for the juvenile and immature Griffon Vultures were the Bosphorus and Iskenderun in Turkey. The main wintering areas were in central and north Saudi Arabia, Israel. One juvenile vulture reached South Sudan which is the first record of the species for the country and one of the southernmost records in Africa. The home range in the wintering areas was 18 933 ± 13 314 km2 (95% KDE) and the size of the core area was 1876 ± 2001.4 km2 (50% KDE). The size of the home range varied among the individuals and the years. In the wintering grounds 78.07% of the area inhabited by the vultures had no vegetation e.g. deserts and rocky mountains. Only 10.05% were covered by sparse vegetation and 8.39% were natural grasslands or arable lands.
Griffon Vultures were feeding at natural carcasses found in the wild in the Eastern Rhodopes in 77.4% (n = 1036) of the recorded cases. In winter 56.5% of the feedings were at the vulture feeding stations while in the summer 80.2% of the feeding events were on occasional carcasses found in the wild. The breeding Griffon Vultures were feeding at the vulture restaurants mostly during the pre-breeding and incubation period (54% and 46.6% respectively). During the post-breeding period 81.6% of the feedings were in the wild. Vultures were landing on the feeding stations on average 53.2 h after carcass disposal. In summer and autumn this period was prolonged up to 10 – 12 days. Griffon vultures were feeding in 42.8% of the days in the month. In the summer they were feeding on average once per 1.6 days and in winter once per 4.1 days. One vulture can visit up to 4 feeding locations per day. The recent study revealed that Griffon Vultures travel significantly longer distances in days when they were feeding on carcasses found in the wild compared to days when feeding at vulture restaurants (t = –11.6 p < 0.001). In addition, they have less straight flight and reach lower displacement when feeding on occasional carcasses (t = 5.9, p < 0.001; t = –7.33, p < 0.001). The average daily distances travelled were 80.3 ± 53.3 km in days when vultures were feeding and only 69.8 ± 58.4 km in days when they did not manage to find food. Our model showed that the season and the age of the vultures determine the most their success in finding food. The other factors which showed correlation were the daily travelled distance, daily displacement, temperature, daily precipitation and wind speed. In 47% of the cases (n = 305) vultures were feeding on cattle carcasses in the wild. In 28% sheep or goats were used for food and wild ungulates were found in 11.5% of the cases. Other species consumed by the vultures were fox, jackal, dog, wild boar, hare, horse and donkey. In 4.6% of the cases vultures were feeding at places where offal from slaughter houses was illegally dumped. The most common reason for the death of the animals consumed by the vultures was carnivore attack (60.2%) while in 37.6% of the cases animals died due to natural causes. However, in 2 occasions death was attributed to poaching.
... Avian vision can also be exploited to aid in the successful relocation of endangered species. Visual conspecific decoys have been used to successfully attract endangered fairy terns (Sterna nereis davisae) to safe breeding areas (Jeffries and Brunton, 2001), and painting rocks to mimic faecal droppings was successful at attracting griffon vultures (Gyps fulvus) to nest on cliffs that had not been chosen as nesting sites by this species for ∼60 years (Sarrazin et al., 1996). Such manipulations may be effective in certain situations for social animals that use visual cues to detect conspecifics, and the efficacy of such manipulations has been formally reviewed (Putman and Blumstein, 2019). ...
Multidisciplinary approaches to conservation and wildlife management are often effective in addressing complex, multi-factor problems. Emerging fields such as conservation physiology and conservation behaviour can provide innovative solutions and management strategies for target species and systems. Sensory ecology combines the study of ‘how animals acquire’ and process sensory stimuli from their environments, and the ecological and evolutionary significance of ‘how animals respond’ to this information. We review the benefits that sensory ecology can bring to wildlife conservation and management by discussing case studies across major taxa and sensory modalities. Conservation practices informed by a sensory ecology approach include the amelioration of sensory traps, control of invasive species, reduction of human–wildlife conflicts and relocation and establishment of new populations of endangered species. We illustrate that sensory ecology can facilitate the understanding of mechanistic ecological and physiological explanations underlying particular conservation issues and also can help develop innovative solutions to ameliorate conservation problems.
... We cannot make further demographic inferences at the population level because of the limitations of our study (relatively short period and small sample size), nonetheless, the scenario is concerning. Griffon vultures lay a single egg, and can start breeding at four years old (Sarrazin et al. 1996) and probably later in dense populations as studied here (Ferrer et al 2004). The viability on this kind of long-lived species is based on adults survival (Saether and Bakke 2000;Schaub et al. 2009;Sanz-Aguilar et al. 2015b;Chantepie et al. 2016).Thus, if the survival detected in Northern individuals is representative of the whole population, a local decline could be expected (see Table S.T.3). ...
Events of non-natural mortality in human-dominated landscapes are especially challenging for populations of large vertebrates with K strategies. Among birds, vultures are one of the most threatened groups experiencing sharp population declines due to non-natural mortality. Factors causing non-natural mortality are usually studied separately. However, the potential use of an integrated index able to predict large-scale mortality risks of avian scavengers could be especially useful for planning conservation strategies. Here, we used the Human Footprint index to examine the impact of landscape anthropization on the survival rates of 66 GPS-tagged adult Eurasian griffon vultures (Gyps fulvus) in two Spanish regions. Foraging in more anthropized areas resulted in a significantly higher individual mortality risk mainly due to collisions with vehicles, poisonings, electrocutions and fatalities with wind turbines. Mean yearly survival rates were estimated at 0.817 ± 0.043 SE and 0.968 ± 0.018 SE for individuals from the more and less anthropized regions, respectively. Additional research should investigate whether some vulture populations could be acting as sinks unnoticed due to metapopulation dynamics. From a broader point of view, our study shows that a straightforward Human Footprint was a useful index to predict the survival of top scavengers and can be highly applicable to planning large-scale conservation measures.
... For the same reason, when some individuals occasionally reach an island, it would be di cult for them to come back onto the mainland. e islands' colonization can be due to exceptional meteorological events such as in the case of Majorca [10], or it can be traced back to the exploration of new areas by young individuals which show a natal dispersion [11], in contrast to adult gri ons that are faithful to their breeding range [12,13]. However, in comparison to adults, juvenile griffons exhibit inferior thermal soaring performance in their rst two months a er edging due to the inexperience in thermal selection and centring, and interthermal gliding soaring [14]. ...
The islands of Sardinia, Crete, and Cyprus are hosting the last native insular griion populations in the Mediterranean basin. eir states have been evaluated from "vulnerable" to "critically endangered". e sequence analysis of molecular markers, particularly the mtDNA D-loop region, provides useful information in studying the evolution of closely related taxa and the conservation of endangered species. erefore, a study of D-loop region sequence was carried out to estimate the genetic diversity and phylogenetic relationship within and among these three populations. Among 84 griion specimens (44 Sardinian, 33 Cretan, and 7 Cypriot), we detected four haplotypes including a novel haplotype (HPT-D) that was exclusively found in the Cretan population with a frequency of 6.1%. When considered as a unique population, haplotype diversity (Hd) and nucleotide diversity () were high at 0.474 and 0.00176, respectively. A similar level of Hd and was found in Sardinian and Cretan populations, both showing three haplotypes. e diierent haplotype frequencies and exclusivity detected were in accordance with the limited matrilineal gene ow (F ST = 0.07097), probably related to the species reluctance to y over sea masses. e genetic variability we observe today would therefore be the result of an evolutionary process strongly innuenced by isolation leading to the appearance of island variants which deserve to be protected. Furthermore, since nesting sites and food availability are essential elements for colony settlement, we may infer that the island's colonization began when the rst domestic animals were transferred by humans during the Neolithic. In conclusion, our research presents a rst contribution to the genetic characterization of the griion vulture populations in the Mediterranean islands of Sardinia, Crete and Cyprus and lays the foundation for conservation and restocking programs.
... Le vautour fauve (Gyps fulvus) est un rapace appartenant à l'ordre des Accipitriformes (Cramp and Simmons, 1980). Sa morphologie ( L'âge de la première reproduction étant de 4 ans (Sarrazin et al., 1996), le vautour fauve fait partie des espèces longévives (à cycle de vie long), caractérisées par un faible taux de reproduction, pour lesquelles la perte d'un individu peut affecter négativement la dynamique de la population d'une manière plus forte que pour des espèces à cycle de vie plus court. Or, l'électrocution et la collision avec les lignes électriques représentent les sources de mortalité principales dans les Causses, avec plus de 80 cas répertoriés (P. ...
La plupart des activités humaines, industrielles ou domestiques, requièrent aujourd’hui l’utilisation d’énergie électrique. Les choix faits pour la production de cette électricité ont nécessité le développement de réseaux de transport d’électricité. En raison de sa densité de câbles, ce réseau induit une fragmentation de l’habitat des animaux volants et principalement des oiseaux. Au-delà des électrocutions au niveau des pylônes, cette fragmentation peut causer la mort d’individus par collision avec les câbles (Bevanger, 1998; Jenkins et al., 2010) et également le dérangement des espèces ou des modifications de leur comportement (Deng and Frederick, 2001; Prinsen et al., 2011; Shimada, 2001). Un grand nombre de facteurs influençant les collisions sont aujourd’hui identifiés (Janss, 2000; Martin and Shaw, 2010). Cependant, la quantification de la mortalité par collision reste complexe en raison de l’hétérogénéité des méthodes utilisées et de l’existence de biais à la quantification (Bech et al., 2012; Ponce et al., 2010). Cette thèse se concentre sur une approche méthodologique de l’étude des interactions des oiseaux avec le réseau de lignes électriques haute-tension (HT) et très-haute-tension (THT) en France métropolitaine. Le premier volet de la thèse concerne la localisation et la hiérarchisation de zones à risque d’interaction pour les oiseaux sur l’ensemble du réseau. Dans ce but, des données de configuration des lignes électriques, de présence (atlas) et de déplacement (couloirs de migration) d’espèces d’oiseaux vulnérables aux lignes électriques sont combinées. Le deuxième volet de la thèse consiste à mettre au point des méthodes qui pourraient permettre de quantifier à l’échelle nationale la mortalité des oiseaux par collision avec les lignes électriques HT-THT. La méthodologie proposée se base sur l’estimation des biais à la quantification, réalisée au cours de la thèse, que sont la détection des cadavres d’oiseaux par les observateurs et la persistance des cadavres sous les lignes électriques. Le troisième et dernier volet de la thèse concerne les modifications de comportement des oiseaux en réponse à la fragmentation de l’espace aérien. Afin de caractériser les mouvements des oiseaux à l’approche des lignes électriques, nous avons adapté une méthodologie d’analyse proposée récemment pour étudier les stratégies d’évitement des oiseaux à différentes échelles spatiales. L’objectif de cette analyse est d’identifier les comportements de vol qui pourraient résulter en une collision avec les câbles. Des données de suivis par télémétrie en trois dimensions (données GPS 3D) de Vautour fauve (Gyps fulvus) sont utilisées dans cette étude comportementale. Ce travail de recherche a permis de proposer un cadre méthodologique pour l’étude des interactions entre oiseaux et lignes électriques et de mettre en évidence l’importance des biais de quantification associés à la recherche de cadavres d’oiseaux sous les lignes. Il a établi pour la première fois une hiérarchisation du risque d’interaction des oiseaux avec les lignes électriques sur l’ensemble du réseau de transport d’électricité français. Les facteurs qui influencent l’utilisation de l’espace à proximité des lignes électriques par les vautours fauves dans les Causses ont également été mis en évidence.
... If conspecific attraction is an important aspect of habitat selection by a species, then all available and optimal sites may not be occupied, including newly created habitat patches. Experimental studies have demonstrated the role of conspecific attraction in several species, using decoys (Kress 1983) or white paint on cliffs (Sarrazin et al. 1996), for example, to establish new populations of seabirds and vultures, respectively. Playbacks have been the most frequently used tool to attract birds to unoccupied sites and have even been used to expand the geographic range of threatened species (Anich and Ward 2017). ...
Some birds use social cues, such as the presence of conspecifics, when selecting breeding habitat. This phenomenon, known as conspecific attraction, has been well‐documented in migratory species, but has not been assessed for resident species of birds. We used Dupont's Larks (Chersophilus duponti) as a model species to determine if conspecific attraction plays a role in habitat selection by resident species of birds. At our study site in Soria province in central Spain, we monitored two potential habitat patches and one managed site where management actions had provided apparently suitable habitat. At each site, we broadcast recordings of the songs and calls of male Dupont's Larks, and monitored their presence during the breeding season and dispersal period in 2018 using automated recorders and field surveys. No birds were attracted to our study sites. Our results suggest that management of patches of suitable habitat should occur close to areas (within 1 km) already occupied by Dupont's Larks to encourage natural colonization because, based on our results, playback of conspecific vocalizations may not attract the species to new breeding areas. However, additional studies are needed before drawing conclusions about the effectiveness of conspecific attraction for this and other resident species of birds. Algunas aves utilizan pistas sociales, tales como la presencia de conespecíficos, cuando seleccionan el hábitat de cría. Este fenómeno, llamado atracción conespecífica, ha sido muy bien documentado en especies migratorias, pero no ha sido evaluado en especies de aves residentes. Utilizamos la Alondra de Dupont (Chersophilus duponti), como especies modelo para determinar si la atracción de conespecíficos juega un rol en la selección de hábitat de especies residentes. En nuestro lugar de estudio, la provincia de Soria en la parte central de España, monitorizamos dos parches dos parches de hábitat potencial, parche donde las acciones de manejo proveyeron de hábitat aparentemente adecuado. En cada localidad, emitimos grabaciones del canto y llamadas de las alondras, y monitorizamos su presencia durante la época de reproducción y el periodo de dispersión del 2018, utilizando grabadores automáticos y censos de campo. Ninguna alondra fue atraída a nuestros resultados sugieren que el manejo de parches de hábitat adecuados debe llevarse a cabo en lugares cercanos a áreas (dentro de un km) actualmente ocupadas por la pecie para favorecer la colonización de las mismas, ya que según nuestros resultados, el uso de grabaciones de conespecíficos pudiera no atraer individuos a áreas nuevas en donde estos puedan reproducirse. Sin embargo, se necesitan estudios adicionales antes de poder concluir sobre la efectividad de la atracción conespecífica, para esta y otras especies de aves residentes.
... Species should be released near areas that can be used as post-release refugia (Bodinof et al., 2012;Jachowski et al., 2016;Jachowski, Slotow, & Millspaugh, 2012), and the timing of release should account for the species' life history and optimize seasonal resource availability (Steury & Murray, 2004). Timing releases before or after major life history events such as reproduction can aid with establishment and overall translocation success (Jachowski et al., 2016;Sarrazin, Bagnolini, Pinna, & Danshin, 1996). In this system, translocated individuals were released in the late summer. ...
Species translocations are increasingly being used as a management tool to mitigate population losses due to such factors as habitat degradation and fragmentation, but post‐introduction follow‐up is relatively sparse. Post‐translocation telemetry can assess success by identifying activity, emigrations, survival, habitat usage, and reproductive events, aiding in the continued management of translocated populations and informing future efforts. This study assessed movement of translocated adult lake sturgeon (Acipenser fulvescens) immediately post‐release and a decade later, and tested for associations between environmental variables and spawning movements. Prior to their translocation in 2002, 13 of 51 adult lake sturgeon were surgically implanted with radio telemetry tags and tracked for 1 year. In 2011 and 2013, eight additional adults were captured within the reintroduction site and implanted with radio‐tags. Six of the 13 sturgeon tagged in 2002 dispersed downstream over a dam during the early post‐release period. In spring 2014, tagged adults were tracked to the spillway at the release area's inflow, and spawning was confirmed by larval captures. Movement data for tagged adults differed between the two tracking periods, showing marked differences in behaviour over time. Water velocity was correlated with upstream and downstream spawning movements, with water temperature also correlated with downstream movement. Research regarding post‐translocation movement and dispersal provides insight on behavioural responses following translocation, and may improve outcomes by informing future efforts.
... Disappearance of a vulture species as a nesting species can be influenced by a number of factors: a decrease in food sources because of changes in livestock; rigorous sanitary laws that control the presence of corpses in the fields; electrocution and collision with wind farms; electrical infrastructures; reduction or abandonment of traditional livestock techniques; and poisoning or use of harmful veterinary products (Seguí, 2006;Donázar et al., 2009;Morales-Reyes et al., 2017). Current practices with appropriately managed dumping sites and promotion of reintroduction projects help the recovery of populations that may have become extinct in some regions (Sarrazin et al., 1994(Sarrazin et al., , 1996Sarrazin and Legendre, 2000). ...
Efectivitat de l’ús de marques alars patagials en el marcatge del voltor comú (Gyps fulvus) a Espanya
Es descriu el disseny de marques alars patagials de lectura dorsoventral d’alta durabilitat per al marcatge i el seguiment d’exemplars de voltor comú Gyps fulvus. Amb aquest objectiu es van marcar ocells aclimatats dins del Projecte Canyet de recuperació del voltor comú com a espècie nidificant al Parc Natural de la Serra de Mariola (Comunitat Valenciana). Un total de 193 voltors van ser marcats en el període 2000-2015 en el punt de mostreig i 43 individus van ser recapturats, amb un valor mitjà de 1.362 dies (SD ± 543,78). De la mateixa manera, es va pesar la meitat de la mostra d’individus capturats (n = 20), els quals van presentar un valor mitjà de 9,11 kg (SD ± 1,14). També es va mesurar l’àrea de les perforacions cicatritzades, la superfície mitjana de les quals va ser de 85,38 mm2 (SD ± 28,61). Les marques alars van proporcionar resultats molt satisfactoris, que permeten aprofundir en els patrons de comportament interespecífic, així com en els moviments de nomadisme. S’ha constatat que el disseny final d’aquestes marques és adequat atès que la identificació a distància és bona i la incidència negativa en els individus és molt reduïda. A més a més, aquest sistema permet la diferenciació d’individus amb una freqüència elevada. S’ha constatat així mateix que aquest dispositiu no interfereix en les etapes vitals de l’espècie i que, adaptant-lo convenientment a escala, resultaria factible per a altres espècies ornítiques.
... In contrast, releases could be scheduled during times of low activity, which may potentially aid in reducing stress-induced dispersal in species highly prone to post-release movements (Jachowski et al., Chapter 9, this volume). Timing releases either before or after major lifehistory events, such as reproduction or dispersal, can aid with establishment and overall translocation success (Lloyd and Powlesland 1994, Bloxam and Tonge 1995, Sarrazin et al. 1996. Conducting multiple releases over time at the same location can also aid with translocation success (IUCN 2013). ...
Releasing individuals is fundamental to reintroductions/translocations. Decisions regarding optimal release techniques may make or break the whole reintroduction program. Selection of potential candidates and potential release areas/sites as well as preparing selected individuals for release and preparing the chosen release sites each have multiple criteria to aid conservation managers to make sound decisions for optimal release strategies. Human dimensions play a critical role in species reintroductions and need to be integrated through-out all release stages. Release strategies should also include multiple risk assessments and exit strategies, including under what conditions would managers remove release animals. Reintroductions are fraught with uncertainty and dilemmas however proper planning, preparing and monitoring involving an iterative process allow conservation managers to utilize adaptive management processes to reduce uncertainty. Perhaps at no other point in the reintroduction process, does one have as much control to react to emerging monitoring data, and to ultimately affect demographic change as through release decisions. Through-out this chapter by drawing upon many examples we demonstrate that sound integration and refinement of release decisions within planning, preparation, monitoring, reflection, and informed management phases can yield optimal benefits for reintroductions, and ultimately for conservation.
... It is expected that habitat selection may involve a hierarchical process with suitable trophic resources at the broadest scales and adequate sites for breeding at the smallest scale (Mart ınez et al. 2003). Thus, to gain better insight into the factors affecting density-dependent changes in productivity (response variable) we considered four spatial scales: metacolonythree clusters of neighbouring colonies more than 30 km apart from each other (Zuberogoitia et al. 2011); colonyclusters of breeding pairs, sometimes including different cliffswe defined colonies as different when the distance between them was more than 1 km without eyries (Sarrazin et al. 1996); cliffboth isolated eyries (only one breeding pair) or group of eyries within a single clifftwo cliffs were clearly separated by evident environmental differences between them (non-rocky areas or different slopes); nest-site, considering every eyrie occupied (egg laid) at least once in the study period. ...
... It was however close to that in the early stages of other reintroduced populations elsewhere, e.g. 0.57 in Massif Central in France (Sarrazin et al. 1996). This might be attributed to the young age of most of the reproducing birds and related lower breeding performance (Forslund & Part 1995, Sanchez-Zapata et al. 2000. ...
The griffon vulture was considered to be extinct as a breeding bird in Bulgaria by the end of the 1960s.
In 1978, the species was rediscovered in the Eastern Rhodopes with one breeding pair and less than 30
immature individuals. Despite the success of the immediately initiated and later intensified conservation
measures the species increased very slowly and in next three decades the breeding area remained relatively
small, ranging 20 to 30 km along Arda River. To boost the recovery of the species along the country, by
means of acclimatization aviaries, releases of captive bred and translocated birds from Spain and France,
has started in 2010. For seven years, more than 275 individuals were freed in five reintroduction sites – four
along Balkan Mountains and one in the Kresna Gorge. In 2016, the first successful fledging of 11 chicks and
total number of 25 breeding pairs marked the successful reintroduction of the species in three new sites, as
follows: Vrachanski Balkan Nature Park – 10 pairs and 4 fledglings; Eastern Balkan Mountains – 8 pairs
and 5 fledglings; the Kresna Gorge – 7 pairs and 2 fledglings. This led to further increase of the national
population of the species with some 20%. Together with the on-going increase of the autochthonous population
in the Eastern Rhodopes (75-80 pairs), the total national griffon vulture population reached 100 pairs
in 13 colonies and the range has tripled from 3,220 km2
to more than 10,500 km2
.
... The productivity of the colony (the number of successfully raised fledglings per number of pairs) is 25%, while the breeding success (the number of the successfully raised fledglings per laid eggs) is 100%. The ratio between the productivity and the breeding success is 25%, which is significantly lower compared to another stable European colo- nies (natural and reintroduced) -65% for Crete (Xirouchakis & Mylonas, 2005) and 79.6% for Central France ( Sarrazin et al., 1994). ...
A group of griffon vultures in Kresna Gorge was studied for its visit on the feeding station next to Rakitna Village after being reintroduced in the area. A camera trap method was used for a better understanding of the breeding behaviour of the griffon vulture, including the intra-and inter-species relations. A statistically significant difference was found between the independent feeding events during the pre-incubation and incubation periods of vultures. The duration of those events also differs, the ones in the second period being longer. Furthermore, a statistically significant difference was observed between the number of vultures per photo for the two sample periods , as a result of a different number of unmarked wild birds and different activity patterns of the nesting pairs. In spite of the fact that the terrestrial predators are also active during the night, their daytime presence leads to a high enough overlap between the two ecological groups, showing that the carnivores are a disturbance factor for the scavengers. The raven is the most abundant species at the feeding site and thus is a food competitor to the griffon vulture. The two species have adapted their behaviour to use the feeding station more successfully during the different biological periods. A significant decrease in the activity overlap between the individuals of the successfully nesting pairs was observed on the feeding station after the beginning of the incubation period. On the other hand, the activity overlap of the unsuccessfully nesting pairs increased in the second sample period. Camera traps can be used in further studies of the mating ecology for individual breeding pairs, when a direct observation on the nest is hard or impossible. This can be a cheap alternative of the time-consuming field observations.
... Our study population was bred in captivity. The demography of translocated populations, especially those based on captive-bred animals, is known to suffer a substantial release cost, influencing their survival, movements and breeding probability (Sarrazin et al. 1996, Bertolero & Oro 2009, Le Gouar et al. 2012. This cost might be explained by genetic processes, such as outbreeding depression, inbreeding, drift loads and adaptation to captivity (Frankham 2008). ...
Identifying factors influencing breeding success in endangered species is vital for undertaking appropriate conservation measures. The reintroduced population of the captive-bred Asian houbara bustard Chlamydotis macqueenii in reserves of the western United Arab Emirates (UAE) has been closely monitored since releases first began in 2005. Based on 8 yr of monitoring data, we provide novel information on female breeding probability and breeding success within a desert ecosystem. Additionally, we explore factors influencing some breeding parameters. Female breeding probability was on average 0.14 ± 0.31 SD (0.01 ± 0.03 for females less than 1 yr old and 0.23 ± 0.38 for females older than 1 yr). Nest initiation date was influenced by temperature and time.
Rainfall during a breeding season increased its length. The estimated nest survival rate for 23 d was 0.52, and was negatively influenced by nest initiation date. Chick survival rate to the age of 6 wk was 0.50 ± 0.39 SD, and survival rate of juveniles in their first year was 0.64 ± 0.02 SE. Our results highlight the ability of captive-bred released houbara in the UAE to breed and of wild born juveniles to survive, 2 vital prerequisites for a successful reintroduction programme. Furthermore, these breeding parameters are similar to the very few that have been reported in other studies of wild resident houbara populations. However, population recruitment rate was low (0.04 individuals per female), resulting mainly from low female breeding probability under harsh weather conditions.
... Conspecific attraction is a habitat selection mechanism common not only in group-living species (e.g. Sarrazin et al. 1994), but also in solitary and territorial ones (Stamps 2001), based on the assumption that presence of conspecifics implies that the habitat patch is suitable for settling. In some cases, observed negative density-dependent dispersal is promoted by fitness benefits of aggregation. ...
Density-dependent dispersal is a common dispersal strategy, mainly as a mechanism of escaping decreased fitness associated with high intra-specific competition. However, in group-living species, high density is expected to be beneficial for the individual, at least up to a certain threshold. A possible mechanism for maintaining an optimal density is negative density-dependent dispersal. In order to examine this hypothesis, we studied the effect of colony density on growth, dispersal and prey capture under different diets in the colonial spider Cyrtophora citricola (Forskl, 1775) (Araneidae). Colonies of C. citricola often reach high densities but the spiders are also capable of living solitarily. Previous studies showed that indirect benefits related to prey capture and predator defense may arise from colony-living, despite the lack of direct cooperation. We found that dispersal propensity of spiders decreased with increasing colony density, and that the effect was strongest when prey abundance was high. Additionally, site tenacity of spider hatchlings increased with greater density of adult females in colonies. Both results support a negative density-dependent dispersal strategy. As expected, body mass of spiders increased with density, suggesting that fitness increases with density (Allee effect). Variance in body mass was higher within dense colonies than among solitary spiders, therefore it is likely that spiders in the colony differ in their prey capture success, and consequently in body mass. This interplay between Allee effect, dispersal strategy and individual fitness may have an important role in the life history and distribution of colonial spiders and of other group-living species.
... Griffon vultures are colonial cliff nesters, generally monogamous, long-lived and philopatric birds. The females lay one egg per year and breeders are faithful to their area of first breeding (Sarrazin et al., 1996;Xirouchakis, 2010). On the contrary, juveniles griffon frequently shows an erratic behaviour (Bernis, 1983). ...
... The establishment of supplementary feeding points for the management of vulture populations has been used during reintroduction programmes to maintain birds Margalida) close to release areas (Griffon Vultures, Gyps fulvus, in France; Sarrazin et al. 1996), to increase food supply (Piper et al. 1999), or even as a potential solution to reduce poisoning (California Condor, in the United States; Meretsky et al. 2000). ...
Detailed, long-term scientific studies are necessary for conservation purposes, but with the main handicap to have the continual economic support required for them. Behavioural and conservation biology studies need long-term projects to achieve robust data, but managers, administrations and policy-makers need, in most cases, immediate results. Here I show several examples of the research obtained from a long-term study (1987–2014) in one of the most threatened species in Pyrenean mountains, the bearded vulture (Gypaetus barbatus), highlighting the importance of such long-term research. The results show how long-term studies are necessary to identify conservation problems, to understand demographic changes on populations and priorities to apply conservation measures. The study’s findings allowed the identification of the negative density-dependent effects on fecundity, the lack of recolonization of new territories outside the current distribution area and the increase in polyandrous trios, suggesting an initial optimal habitat saturation. From a management point of view, the studies show that supplementary feeding sites (SFS) can have detrimental effects on fecundity but increases pre-adult survival. Also, illegal poisoning is increasing, and the demographic simulations suggest a regressive scenario in population dynamics if this factor is not eliminated. More recently, anthropogenic activities through human health regulations that affect habitat quality can suddenly modify demographic parameters. The results obtained about changes in nest-site selection, mating system and demographic parameters can only be achieved through long-term studies, suggesting the importance of long-term research to provide accurate information to managers and policy-makers to optimise the application of conservation measures.
... Overall, the mean hatching and fledging success of the population of Griffon Vultures at Gamla Nature Reserve were far below the 95% fledging success reported for the same species in Cyprus by Iezekiel et al. (2004) or the 74% fledging success in Crete by Xirouchakis (2010), or the 62.5% fledging success reported by Sarrazin et al. (1996) for the Grand Causses in southern France. Not all the nesting sites of Griffon Vultures in Gamla Nature Reserve had the same frequency of breeding attempts over the years, and we showed that this variability was associated with fledging success and with nest attractiveness-more frequently used sites had higher fledging success, and breeding there started earlier in the season. ...
Gamla Nature Reserve once held the largest colony of nesting and roosting Griffon Vultures (Gyps fulvus) in Israel, with 45 to 57 pairs nesting at the colony during our study years (1998-2002), and up to 140 individuals roosting on the canyon's cliffs. Nevertheless, the fledging success there was very low: only 34% of breeding attempts (nest with eggs laid) resulted in fledged young during our study. Poisoning and hunting were the main causes of mortality, but in addition, a shortage of appropriate nesting places may also have been an important limiting factor. Fledging percentage was correlated with nest-site use and "attractiveness": nest sites with greater fledging percentage also had more breeding attempts and were inhabited earlier in the nesting season. The main physical characteristic that enhanced breeding success was the type of nest site; nests in caves were more successful and were used for more breeding attempts than nests that were exposed from above. The influence of microclimatic conditions on nesting success was emphasized by the differences in the intensity of parental care, particularly activities associated with thermoregulation, between parents at the different types of nest sites. Parents at exposed nests invested substantially more time in thermoregulation (i.e., brooding or shading the young), an investment that was negatively correlated with breeding success.
... However, specific knowledge of Cape Vulture nest-site selectivity and factors that influence breeding success is lacking. Understanding the use of rock formations by Cape Vultures can help to identify ideal breeding sites that could be used in future reintroduction efforts or current conservation planning polices in addition to providing information on nest-site factors that may influence breeding success (Ceballos & Don azar 1989, Sarrazin et al. 1996. Gyps vulture pairs reuse a successful nest-site and exhibit a win-stay, lose-switch strategy (Robertson 1986, Switzer 1997, Borello & Borello 2002, Virani et al. 2012). ...
The breeding success of endangered colonial nesting species is important for their conservation. Many species of Gyps vultures form large breeding colonies that are the foci of conservation efforts. The Cape Vulture is a globally threatened species that is endemic to southern Africa and has seen a major reduction in its population size (≥50% over 48 years). There is evidence that breeding colonies are prone to desertion as a result of human disturbance. Factors that influence the occupancy and breeding success of individual nest sites is not fully understood for any African vulture species. We investigated cliff characteristics and neighbour requirements of the Msikaba Cape Vulture colony, a major breeding colony in the southern node of the population in the Eastern Cape, South Africa, together with their nest site occupation and breeding success over 13 years. In total, 1767 breeding attempts were recorded. Nest sites that had a higher elevation, smaller ledge depth, greater total productivity and were surrounded by conspecifics were more likely to be occupied, although the amount of overhang above the nest was not an important predictor of occupancy. In accordance with occupation, nest sites with a smaller ledge depth had higher breeding success; however nests with a greater overhang were also more successful and height of the nest site was not an important predictor of breeding success. The breeding success of a nest site in a given year was positively influenced by the number of direct nest neighbours, and nests in the middle of high density areas had greater breeding success. This suggests that maintaining a high nest density may be an important consideration if declines of reproducing adults continue. Breeding success declined over the study period, highlighting the effects of a temporal variation or observer bias. Our results identified optimal nest site locations (ledge depths of 1 m, and at a height of 180 m) and their effects on breeding success. This information can be used for planning reintroduction efforts of the endangered Cape Vulture and for their ongoing conservation. This article is protected by copyright. All rights reserved.
... According to Sarrazin et al., (1994), the trend of this mechanism might lead to the island biogeographic concept projects that smaller microhabitats should contain fewer. ...
The study represents the first scientific research on factor of trapaeng influence waterbirds abundance and richness, while waterbirds defined as the vital component of world biodiversity. The study focused on evaluated the trapaeng factors including tapaeng size, extended trapaeng microhabitat patches, distance and surrounding forest habitats influence on waterbirds and the impact of agriculture on waterbirds abundance and richness.
Waterbirds might heavily depend on diversity of trapaeng microhabitat with homogeneities of vegetation structures, spatial configuration. Waterbirds have higher density within distance 0-4 konometer for settlements. There was positive relationship between trapaeng sizes and waterbird abundance and richness, but most likely preferred negative relationship with the surrounding forest habitat. The larger tapraengs with approximately 0.05/m² of tree density and 7.5 m height are considered the best criteria for waterbirds. Water buffalo was indicted as benefit waterbirds by grassing, tramping and wallowing activates at trapaeng habitat, created an accessibility of foraging habitat for birds. Buffalo likely to walked faraway in the deep forest in the dry season > 8 kilometers from settlements, while the domestic cattle prefer to stay close to the settlements within 0-4 kilometres and provide less benefit to waterbirds. The study has indicated that the forest trapaengs are significant important for waterbirds than the cultivated trapaeng did. The high probability of waterbirds density observed at forest trapaeng which linkage to some specific characteristic that the cultivated trapaeng did not exist, including multiple-microhabitat patches, diverse of heterogeneity spatial configuration and vegetation covers.
Waterbirds preferred to be at trapaeng that still remain water inside rather than the one didn’t. Trapaengs that have year round of water inside can provide best alternative ecology of waterbirds and easy to monitor and conserve. Land or trapaeng conversion to cultivated area might be the main threat to waterbirds in losing their diverse foraging habitat. The effectiveness-managed mechanism of natural trapaengs in the Western Siem Pang is really needed to conserve those rare waterbird species.
... Few empirical studies have examined the populationlevel consequences of information use (but see Ponchon et al. 2015) or how individuals weigh personal and social information (Fletcher 2006;Fletcher and Sieving 2010). Current case studies include conspecific attraction based on location and population density as cues for habitat quality (e.g., Forbes and Kaiser 1994;Sarrazin et al. 1996;Huijbers et al. 2012). For example, Fletcher (2009) suggested that infrequent occupancy of small habitat fragments in least flycatchers (Empidonax minimus), a common pattern in birds, may be due to reduced conspecific cues ultimately resulting in habitat underutilization. ...
Social information is used widely in breeding habitat se- lection and provides an efficient means for individuals to select hab- itat, but the population-level consequences of this process are not well explored. At low population densities, efficiencies may be reduced be- cause there are insufficient information providers to cue high-quality habitat. This constitutes what we call an information-mediated Allee effect. We present the first general model for an information-mediated Allee effect applied to breeding habitat selection and unify personal and social information, Allee effects, and ecological traps into a com- mon framework. In a second model, we consider an explicit mech- anism of social information gathering through prospecting on con- specific breeding performance. In each model, we independently vary personal and social information use to demonstrate how dependency on social information may result in either weak or strong Allee ef- fects that, in turn, affect population extinction risk. Abrupt transitions between outcomes can occur through reduced information transfer or small changes in habitat composition. Overall, information-mediated Allee effects may produce positive feedbacks that amplify population declines in species that are already experiencing environmentally driven stressors, such as habitat loss and degradation. Alternatively, social in- formation has the capacity to rescue populations from ecological traps.
The current study analyses and presents the results of the ten-year establishment phase of the Griffon Vulture (Gyps fulvus) local re-introduction in Vrachanski Balkan Nature Park, north-western Bulgaria. Between 2010 and 2020, 61 rehabilitated and captive-bred Griffon Vultures from Spain, France and several European zoos were released from an acclimatisation aviary. The first successful breeding in the wild was reported in 2015. Thus, the species has been restored as a nesting species in the area after more than 60 years of absence. In 2020, the local population accounted for some 55–70 individuals, consisting of about 20–23 breeding pairs in three-five separate colonies and two frequently-used roosting sites. Forty-two chicks fledged from 2010 to 2020, at an average breeding success of 0.46 chicks/territorial pair and productivity of 0.62 fledglings/breeding pair. The mortality rate is calculated at 0.34; an additional 0.07 of the released individuals have never been seen or found. The local nucleus of the Griffon Vulture now covers a territory of 1,478.58 km², calculated as a 95% home range, while the 50% core area is 9.07 ± 5.73 km2 (range 2.12–22.89 km2). With these results, we consider the establishment phase of the re-introduction of the species in Vrachanski Balkan Nature Park as completed.
The current work presents the preliminary results of the Cinereous Vulture (Aegypius monachus) releases in the Balkan Mountains in 2018–2022, aiming at the species re-introduction in Bulgaria, where it was listed as locally extinct since 1985. The first imports and releases of Cinereous Vultures in Bulgaria started in 2018. Until mid-2022, 72 individuals were released in the Eastern Balkan Mountains (Kotlenska Planina SPA and Sinite Kamani Nature Park) and Vrachanski Balkan Nature Park. Of them, 63 immatures imported from Spain were released from aviaries and nine juveniles captive-bred in European zoos were released by hacking (fledging from an artificial nest). We compared the success in survival and establishment between the different release sites and methods used to adjust the ongoing technics and tactics and to support knowledge improvement for future similar projects.
From the nine Cinereous Vultures released by hacking, the results were as follows: 1.00 fledging success, but only 0.22 survival in the first six months – combined period of acclimation, first migration and the first winter. All survivors from that period reached maturity into the wild, but all emigrated from the release site and settled elsewhere.
Of the 63 individuals released by aviaries, 32 individuals were released in the Eastern Balkan Mountains (18 individuals are still alive – 0.56 survival; 14 individuals settled in the area, which accounts for 0.44 of all released birds and 0.78 of the survivors). Thirty-one individuals were released in Vrachanski Balkan Nature Park (23 individuals are still alive – 0.74 survival; 22 individuals settled in the area – 0.71 of all released birds and 0.96 of the survivors). Based only on aviary method comparison, the settling of the individuals in the release area was alike in the two sites. However, the Vrachanski Balkan Nature Park performed better in survival – both in acclimation and establishment periods.
While comparing the release methods – hacking and release from the aviary – the following results were observed: the survival rate during acclimation was 0.86. Due to more considerable losses during the first migration and dispersal in the individuals released by hacking, the survival rate of 0.22 was significantly lower compared to 0.73 for the birds released from the aviary. Additionally, in both methods, a similar pattern in the first winter and spring migration dispersal was observed. Although the survival was equal in the released-by-hacking or aviary birds after the first year onwards, it is essential to note that the emigration of the hacked birds from the release site was 1.00. In comparison, the birds released from aviaries largely remained and settled in the release area (> 0.77 of the survivors). The cost of release and related acclimation, settling, dispersal and the first winter was the greatest: 0.12–0.17 per period, or cumulatively, it was about 0.27. Survival increased and stabilised to > 0.90 after the first year in the wild and reached nearly 1.00 after two years in the wild onwards.
Two distinct nuclei of the Cinereous Vulture were established along the Balkan Mountains – the Eastern Balkan Mountains with 18–23 individuals and four formed pairs using a territory of about 642.74 km2 – 95% home range and 85.72 km2 – 50% core area with center being the town of Kotel; and Vrachanski Balkan Nature Park with present 23–29 individuals, of which 2–3 pairs formed so far, using a territory of about 1,143.66 km2 – 95% home range and 22.89 km2 – 50% core area with center being the village of Zgorigrad. The species readily accepted breeding in artificial nest platforms built by professional arborists on different tree species – oak, beech, sycamore and pine. The only naturally built nests were on the ground (n = 2) (unsuccessful) and in Scots Pine (n = 1) (successful). In 2021 and 2022, in each of the two sites, the first successful reproductions were recorded, which marked the return of the Cinereous Vulture as breeding species – 28 years after the last occasional record of a single breeding pair in the country and 36 years after it was officially listed as locally extinct in Bulgaria.
An increasing number of reintroduction programs have been set up in recent years in an attempt to reintroduce once extinct species to their indigenous ranges and create self-sustaining populations. However, the released individuals often experience low mating success and fecundity. Appropriate rearing in captivity is considered essential for the successful post-release reproduction of captive-reared individuals. Low post-release mating success and fecundity are also issues in reintroduced Crested Ibis Nipponia nippon populations on Sado Island. These phenomena may be caused by the effects of hand-rearing in captivity, yet temporary hand-rearing is necessary when captive breeding, because rescuing embryos from mortality is essential due to the abnormal behavior of parent birds in captivity. Therefore, the establishment of rearing methods that temporarily protect embryos or chicks while limiting the negative effects of hand-rearing on breeding after release is needed. To overcome these challenges, we tested how captive rearing methods impact post-release courtship behavior, mating success, and fecundity of the ibis. By combining detailed rearing history in captivity with long-term post-release monitoring, we demonstrate that the initiation of parental rearing before the chicks' eyes open is the critical factor leading to increased pseudocopulation frequency and mating success in captive-born male ibis. Based on these results, not hand-rearing the chicks beyond the day after hatching would reduce the impact of hand-rearing on reproduction after release. Rearing methods that take into account the nestling period should be implemented to enhance the efficiency and reduce the cost of avian reintroduction projects.
The current study presents and analyses the results from the recently completed 11-yearestablishment phase, following the start of the local re-introduction of the Griffon Vulture (Gyps fulvus) in Kotlenska Planina SPA and Sinite Kamani Nature Park in the Eastern Balkan Mountains of Bulgaria in the period 2010-2020. As a result of the re-introduction efforts and release of 153 individuals, the Griffon Vulture has been successfully reproducing again in the Eastern Balkan Mountains since 2016, after more than 40-50 years of absence. At 2020, the local population consists of some 80 local and up to 80-115 birds, together with sojourn individuals. Amongst them, 23-25 breeding pairs, located in five different colonies and two more frequently used roosting sites. The current average productivity remains relatively low: 0.41 fledglings/territorial pair and fledging success of 0.61 fledglings/breeding pair between 2016 and 2020, but shows a trend to increase with time and the growing experience of the young locally re-introduced population. The mortality confirmed between 2010-2021 accounts for 33%, mostly due to electrocution as a post-release effect in the first six months following their release. Our data show that the newly established population in the Eastern Balkan Mountains mostly forages on feeding sites, having a comparatively small 95% home range: 281.88 ± 91 km and 50% core area: 6.6 ± 2.28 km (range 4.7–8.5 km ). We, therefore, consider the establishment phase of the re-introduction of Griffon Vulture in this particular site as successfully completed, but management should continue. Furthermore, the area of the Eastern Balkan Mountains can currently be regarded as a "source" for the species within the source-sink population regulation concept in the national and Balkan context.
The Eurasian griffon population in Serbia declined throughout the 20th century from widespread to a rare species, counting a total of 14 detected pairs in two colonies in western Serbia in the 1990s. Although the conservation measures have been implemented since the 1970s, they have had little effect on the further population decline until the supplementary feeding program started in 1989. In this paper, we present the results related to the population trends and reproduction parameters, following the establishment of a supplementary feeding program of the Eurasian griffon in Serbia based on a 34-year survey (1985–2018). By 2018, a total of 2458 tons of supplementary food was provided at three feeding stations. The population increased from 14 detected pairs in two colonies in 1992 to 262 detected pairs in four colonies in 2018. A total of 1807 juveniles were fledged, with breeding success – fledged chicks/laying pairs (i.e., breeding pairs) (0.81 ± 0.07; mean ± SD) and productivity – fledged chicks/detected pairs (0.57 ± 0.10). The amount of supplementary food was in a significant positive correlation with the number of detected and breeding pairs and the number of fledged juveniles. Furthermore, breeding parameters remained high despite the substantial increase in population size, implying that the population is far from saturation level. Our study emphasizes the importance of applied protection measures, especially supplementary feeding. The implementation of appropriate networks of feeding stations and the promotion of free-range livestock farming, as well as returning to the traditional way of disposing of dead cattle, would be a recommendation for future main conservation activities for the Eurasian griffon population in Serbia.
Social living can be facilitated by cooperative advantages, yet also incurs in important competitive interactions, leading to complex patterns of spatial genetic structure. Vultures provide a valuable example of complex social animals, with potential conflicts between cooperative and competitive behaviors. Yet, little is known about the socio-genetic structure of this guild because of the inherent difficulties of sampling highly mobile species with large geographical ranges. Herein, we genotyped 300 non-invasive samples from Andean condor (Vultur gryphus) with microsatellite markers to investigate the social dynamics in this highly vagile vulture that possess a despotic social system and communal roosting behavior. We explored the role of age and sex in the dispersion and relatedness patterns of the Andean condor across the central region of Argentina. We provided evidence of age-biased dispersal, supporting the idea that immature condors are largely nomadic using temporary roosting sites during exploratory flights. Our results also insinuated that sex-biased dispersal is age-dependent, with male-biased dispersal during the early life stage, suggesting habitat exclusion by adult male despotic competition. Finally, our kinship analysis showed that regional clusters are composed of highly related adults, indicating the retention of intergenerational family members. Collectively, these results demonstrate that kin associations are driven by adult philopatry, and possibly maintained by fitness benefits of social cooperation for this species.
Significance statement
An important question in behavioral ecology is how and when does group living affect population structure and space use. We show that adult Andean condors exhibit philopatric behavior, resulting in kin structuring patterns. Family coalitions may facilitate cooperative strategies to locate and secure costly resources, resulting in indirect fitness benefits. However, immature individuals seem to be excluded from adult territories due to despotic competition or because of an innate exploratory behavior, resulting in a scattered distribution pattern. Understanding the genetic consequences of social dynamics not only increase our knowledge of the behavioral ecology of elusive wide-ranging species, but is also essential in wildlife monitoring to design effective genetic sampling.
Wildlife conservationists and managers must address a wide range of issues relating to bird populations including sustainable management of the wider countryside, the protection of individual sites and site networks and properly planned species recovery. Sound approaches to these problems need to be based on a good understanding of the population processes involved. Much of the research that provides such understanding is based on ringing, which is used to measure many aspects of avian demography, particularly survival rates, recruitment and dispersal. Ringing studies have allowed the demographic causes of population declines to be identified, providing indications and tests of their environmental causes. Spatial population modelling, supported by good empirical data on dispersal, has the potential to contribute to both species and landscape conservation. The success of rehabilitation and reintroduction programmes can often be evaluated from studies of marked birds. Descriptions of patterns of movements form an essential part of the information required to manage flyway populations and site networks. Ringing is also a key component of research into the effects of hunting because it can be used to measure both harvest and survival rates. The control of gull populations illustrates the application of population dynamics principles to reduce population size. The contribution of ringing to conservation science during the 21st century can be enhanced by using information technology to improve the use of existing information and data, by undertaking more long-term monitoring and through giving careful attention to the design of research projects.
The Griffon Vulture (Gyps fulvus) is a listed species as a result of human activities. Lack of food is considered to result not only in reduced reproductive success but also to cause increased mortality in free-ranging adults. Ptilochronology is a non-invasive technique that allows evaluating the comparative nutritional status of individuals of different age and sex groups of different geographic regions in a wide range of habitats. One of the few countries where Griffon Vultures are still abundant is Spain and a comparatively large number of individuals that are brought to rehabilitation centers following injuries in the wild. We collected the central rectrix of all Griffon Vultures brought to rehabilitation centers in northwestern Spain. Of a total of 95 vultures sampled, 63 were juveniles (66%; first year of fledging), 12 (13%) sub-adults, 16 (17%) adults and 4 (5%) adults that were captive for more than 10 years. The last allowed us to compare the optimal nutritional condition attained by birds held in captivity and had access ad libitum to food and water. The average growth bar for captive birds was 7.7 + 0.9 mm/day, in free-living adults was 5.9 + 1.0 mm/day, in sub-adults 6.8 + 0.5 mm/day, and in fledglings was 6.8 + 0.8 mm/day. The average number of stress bars per feather was none in captive birds, 4.5 + 3.7 in adults, none in sub adults, and 1.1 + 1.9 in fledglings. Fledglings were in significantly better nutritional condition than free-living adults (Wilcoxon signed-rank test z = -2.726, P = 0.006), but were not different from sub-adults (z = -0.535, P = 0.593) or captive birds (z = -1.461, P = 0.1441). Analyses showed no relationship between the width of the growth bars and the number of fault bars found on each feather in juveniles (y = -0.226x + 2.65, r2 = 0.008) and is in contrast to adults (y = -2.082x + 16.67, r2 = 0.308). Hence, we conclude that free-living adults had the worst nutritional condition of the four age groups studied and are the most adversely affected by environmental stresses and parents buffer their nestlings from nutritional stress, especially during periods of food scarcity. Sub-adults are not involved in the reproductive effort and appear to be able to allocate greater resources to self-maintenance. However, the small sample size of sub-adults prevents us from reaching proper conclusions. The above proves that ptilochronology can be used as a conservation tool to evaluate the comparative nutritional condition of Griffon Vultures, and other large raptors, and will allow sincere authorities to pre-empt and implement conservation measures in a timely manner.
ABSTRACT.-The primary goal in the recovery of any formerly extirpated taxa is the establishment of a viable, self-sustaining breeding population. Reintroduced populations of the endangered California Condor (Gymnogyps californianus) began breeding in southern California and northern Arizona in 2001. Here, we studied breeding condors in southern California from 2002-2005 to determine nest success and identify limiting factors for nesting condors. Although hatching success (66.7%) was comparable to the historic wild population of the 1980s, fledging success was extremely low (8.3%). Of 10 chicks hatched in the wild since 2001, only one survived to fledge successfully. All post-hatching mortality since 2002 occurred in the mid to late nestling phase. In two cases, heavy metal toxicosis and complications due to the ingestion of foreign material, principally man-made trash, were the cause of death. All but one chick handled since 2002 held such trash (up to 193.5 g). On average, feeding rates were similar to those at historic nests but were more variable. Most nests had lower feeding rates and more prolonged periods of food deprivation than historical nests. Our data suggest that management, principally provisioning at single sites, has significantly altered foraging behavior with detrimental effects on chick survivorship. Whether trash ingestion is related to calcium or other nutritional requirements needs urgent investigation. As a priority, we recommend determining the timing of bone mineralization, and capacity for pellet formation and regurgitation, of nestlings in captivity. In the wild, we recommend the removal of problem birds, closing or cleaning up trash sites and, most importantly, altering current management to reduce dependence on single provisioning sites to promote the development of more natural foraging patterns. However, this is likely to come at a cost of increased exposure to lead contamination. Removal of the threat of lead poisoning would allow more flexible and scientifically driven management of condor populations.
The quality of a bird’s breeding site is a primary determinant of its success or failure to reproduce there. We expect birds to devote considerable effort to acquiring accurate information about potential locations before finally selecting a breeding site (e.g., Wiens, 1976; Lack, 1971; Howard, 1920). The great mobility of birds strengthens this expectation, which is also reinforced by the accumulating evidence of avian cognitive abilities (e.g., Cook et al., 1997; Cook, 1993). In this chapter we review theoretical considerations and empirical evidence that birds gather advance information about possible breeding sites within a general area before settling to breed within that area. This gathering process, which we term prospecting, has received little systematic attention despite its potential interest and its obvious importance for individual fitness, population dynamics, and distribution.
Although senescence has been described for various fitness components in a wide range of animal species, few studies have studied senescence in long-lived species, and little is known about its interactions with environmental variation. Using a 32 year capture-mark-recapture dataset on the griffon vulture Gyps fulvus, we examined the demographic patterns of actuarial senescence and the patterns of year-to-year variation in survival rates. We found a significant, surprisingly late, decrease of annual survival probabilities from the age of 28 years onward and divided individual lifetimes into to three categories (juvenile, mid-age and senescent birds). In agreement with the environmental canalization hypothesis, our analyses uncovered 1) higher temporal variation of annual survival probabilities in both the juvenile and senescent age classes compared to the mid-age class and 2) low sensitivity of the population growth rate to the survival of both the juvenile and senescent age classes. Our results further suggested that the temporal variation in the survival of senescent birds might be related to intra-annual changes in air temperature amplitudes. Finally, using population dynamics modeling, we revealed contrasting effects of the inclusion of the senescent age class on predicted population growth, depending on how survival rates were modeled. Altogether, our results demonstrate the existence of a class of senescent birds that exhibit distinct demographic properties compared to juvenile and mid-age classes.This article is protected by copyright. All rights reserved.
Nous exposons dans cet article une méthode pratique d'analyse de viabilité des populations. Nous envisageons le cas de populations structurées en classes (selon l'âge, le sexe, ]'état reproducteur, la localisation, etc.) et dont les paramètres démographiques correspondant aux transitions entre classes sont connus. Pour analyser le risque d'extinction et définir des objectifs de gestion en termes démographiques, nous recommandons de procéder en trois étapes. (l) Construction d'un modèle matriciel constant combinant les valeurs moyennes des paramètres. Les effectifs de chaque classe de la population peuvent être liés d'une année à l'autre par une matrice de transition qui regroupe les paramètres démographiques. Lorsque les paramètres sont constants (fixés à leur moyenne), l'analyse de cette matrice fournit le taux d'accroissement déterministe de la population, sa structure (e.g., la pyramide des âges), les valeurs reproductives par classe et les sensibilités du taux d'accroissement aux variations des paramètres. (2) Évaluation du risque d'extinction dû aux facteurs.stochastique : stochasticité démographique, variabilité environnementale, catastrophe. Nous montrons comment on peut obtenir le taux d'accroissement stochastique, la probabilité d'extinction et la distribution du temps d'extinction sur la base des calculs déterministes (étape 1) et de simulations de Monte-Carlo. (3) Détermination des objectfs de gestion et amélioration du suivi des populations. Le risque d'extinction d'une population peut être réduit par l'augmentation du taux d'accroissement, la réduction des variations temporelles de celui-ci, et par l'augmentation de l'effectif actuel de la population. L'analyse des élasticités (sensibilités relatives) du taux d'accroissement dans le modèle déterministe permet d'identifier les paramètres démographiques dont la modification entrainera le plus directement l'augmentation du taux d'accroissement. De plus, il est possible de décomposer la variance du taux d'accroissement pour déterminer sa source principale (valeur moyenne des paramètres, ou leur variabilité temporelle). Enfin, l'étude des valeurs reproductives et de leur sensibilité permet d'identifier les classes de la population dont le renforcement produirait l'effet le plus durable sur le redressement de la population. Le logiciel ULM permet de réaliser l'ensemble de ce plan de manière automatique. L'utilisateur décide de la représentation du cycle de vie de l'espèce étudiée (nombre et nature des classes, transitions...) et programme le modèle matriciel dans un langage convivial en gardant toute latitude quant aux facteurs de variation des paramètres (facteurs aléatoires, densité-dépendance...). Tous les paramètres de viabilité de la population (taux d'accroissement, sensibilités, probabilités et temps d'extinction, élasticités, etc.) sont calculés par le logiciel. La méthode générale et sa mise en oeuvre informatique sont ici illustrées au travers de deux exemples : l'analyse de viabilité d'une population isolée de Vipère d'Orsini (Vipera ursinii ursinii) dans les Alpes méditerranéennes et l'évaluation d'une stratégie de réintroduction du Vautour fauve (Gyps fulvus fulvus) dans les Cévennes.
High post-release survival, low dispersal and the recruitment of captive-reared individuals into the wild population are critical to the success of any reintroduction programme. Reintroducing a migratory species poses an additional challenge as success also depends on the return of captive-reared individuals to breeding grounds in subsequent years. We investigated the effects of seven husbandry and management factors on the return rate of captive-reared eastern loggerhead shrikes
Lanius ludovicianus migrans
and documented the recruitment of returning individuals. During 2004–2010, 564 juveniles were released in Ontario, Canada, as part of a field propagation and release programme and there were 27 confirmed sightings of returning birds during 2005–2011. Returning birds were significantly more likely to have been released in large groups of juveniles (9–10 birds) at 5.5 weeks post-fledging from the Carden field propagation site. Comparisons of the number of young fledged and survival to 2 weeks post-fledging revealed similar results for pairs comprising one captive-reared and one wild-reared individual and pairs comprising two wild individuals. These results highlight the contribution of captive-reared shrikes to the recovery of the wild population and the importance of monitoring outcomes and evaluating techniques.
Colonial nesting in seabirds and other water birds is widespread, but it is relatively rare in other birds (Lack, 1966). A colony is a breeding aggregation of birds characterized by many individuals nesting close to each other, generally feeding outside the nesting area, and organized by various types of social stimulation and elements of flock behavior and other features (Crook, 1965; Modestov, 1967; Zubakin et ai., 1983; Götmark and Andersson, 1984). Colonies may have an internal structure in which there are elements of territoriality and social synchrony (Naumov, 1972). The processes of how colonies form and function have been investigated emphasizing two distinct points of view. The first is the phylogeny of coloniality—the formation of colonies in context of evolutionary processes; the second is the ontogeny of coloniality—the formation of colonies during the season of reproduction.
If fecundity is clearly defined with respect to other demographic parameters, its estimation does not raise major problems. Data and methods for analysing survival rate are numerous although problems still exist in obtaining survival rates of young individuals. Data on age-specific proportions of breeders and immigration-emigration processes are scarce. Methods of population size estimation are divided into those that give a relative estimation and those that give an absolute one. The reliability of the former depends on a variety of assumptions which clearly need to be tested fully. Review of the literature leads to the following conclusions: 1) More data have to be collected for the estimation of some parameters (immigration-emigration, age-specific proportion of breeders). 2) The philosophy of the methodological development seems to be driven by the following principles: hierarchy of models, test between models, numerical estimations, and powerful goodness-of-fit tests. 3) Communication between biologists and statisticians has to be increased as well as transfer of techniques from other fields. 4) The sampling design and the methodology chosen need to be in agreement with managers' and conservationists' requirements. 5) Rare or shy species offer little possibility to get precise estimation of demographic parameters. Acquisition of high quality data, comparison with similar species and the exploration of theoretical or predictive models may be good ways of overcoming this difficulty. -from Authors
Using field data on fecundity, age at first reproduction and adult life expectancy, we reconsider the so-called r-K gradient by analyzing relationships between these three demographic parameters in 80 mammal species and 114 bird species. After the allometric effect of adult body weight is removed, the three variables remain correlated. The existence of demographic tactics which are independent of adult body weight is demonstrated by multivariate analyses of these variables. These analyses confirm the importance of ecological and phylogenetic constraints. The main structure is a time-scale gradient ranking species according to turn-over, both in birds and mammals. A second gradient ranking species according to iteroparity level appears significantly both in birds and mammals. In mammals, this pattern is related to patterns of parental investment.
We provide a statistical framework to estimate age-specific breeding probabilities in vertebrate populations, from recaptures or resightings of individuals marked as young. We consider here data collected at one or possibly several points over time, but without information on individual fate over time, leading to models which we can call transversal models. When the adult survival rate is known, explicit estimates are obtained. When data on individuals marked as adults are also available, the adult survival rate and the age-specific breeding probabilities can be approximately estimated using log-linear models, with greater flexibility. An example of resightings of black-headed gulls Larus ridibundus is treated.
Analysis of population trends among breeding groups of Griffon Vultures on the northern face of the western Pyrenees (number of pairs, breeding success, composition and size of groups) between 1976 and 1982 suggests that the measures now being taken to protect the species (artificial feeding, protection of breeding sites) have contributed towards an increase in the number of breeding pairs. In the longer term, however, the maintenance of pastoralism is necessary in order to ensure the continuance of a vulture population in the region. RESUME L'analyse des tendances démographiques actuelles des groupes de reproducteurs du versant nord des Pyrénées occidentales (nombre de couples, fécondité, structure et taille des groupes), de 1976 à 1982, suggère que les mesures actuelles de protection de l'espèce (mise en place de charniers, protection des sites de reproduction), ont contribué à augmenter les effectifs reproducteurs. Cependant, à plus long terme, le maintient d'un équilibre dynamique entre vautours et pastoralisme est necessaire.
Animal and plant populations often occupy a variety of local areas and may experience different local birth and death rates in different areas. When this occurs, reproductive surpluses from productive source habitats may maintain populations in sink habitats, where local reproductive succes fails to keep pace with local mortality. For animals with active habitat selection, an equilibrium with both source and sink habitats occupied can be both ecologically and evolutionarily stable. If the surplus population of the source is large and the per capit deficit in the sink is small, only a small fraction of the total population will occur in areas where local reproduction is sufficient to compensate for local mortality. In this sense, the realized niche may be larger than the fundamental niche. Consequently, the particular species assemblage occupying any local study site may consist of a mixture of source and sink populations and may be as much or more influenced by the type and proximity of other habitats as by the resources and other conditions at the site. -Author
In a region of northern Spain the griffon vulture Gyps fulvus population remained stable between 1969 and 1975, hovering around 282 pairs in 23 colonies. In 1979 there were 364 pairs in 26 colonies, in 1984, 589 pairs in 32 colonies, and in 1989, 1097 pairs in 46 colonies. Previously, in the 1950s and 1960s, the population had decreased. The recovery of the species may have been caused by the cessation of human-induced mortality. The creation of feeding stations did not have positive effects because there has always been enough food available to maintain the vulture population.
Robertson, A. S. 1984. Aspects of the population dynamics of Cape Vultures in the Cape Province. Ostrich 55: 196–206.Information gathered in 1981 and 1982 and collated from previous records on the numbers, spatial distribution, proportion of age classes, age and frequency of breeding, breeding success and causes of breeding failure, and the survival of immature and adult Cape Vultures Gyps coprotheres in the southern and southwestern areas of the Cape Province, South Africa, is presented. This sub-population of about 75 birds is apparently isolated from conspecifics in the rest of southern Africa; the implications of this are discussed. At the Potberg colony in both years an average of 85% of birds 5 years and older were involved in breeding attempts. The age of first breeding was 4–6 years. Nest sites were active for about two in every three years. Between 1975 and 1982, 0,51-0,67 nestlings were reared per active nest site (n=165). Four (possible maximum six) of 21 immatures were resighted one year after they had flown. Of 123 birds that had been ringed at Potberg to 1980, 14 (11%) were sighted in 1981; only four of 48(8%) colour-ringed birds 5 years old and older were breeding in 1981.
Animal and plant populations often occupy a variety of local areas and may experience different local birth and death rates in different areas. When this occurs, reproductive surpluses from productive source habitats may maintain populations in sink habitats, where local reproductive success fails to keep pace with local mortality. For animals with active habitat selection, an equilibrium with both source and sink habitats occupied can be both ecologically and evolutionarily stable. If the surplus population of the source is large and the per capita deficit in the sink is small, only a small fraction of the total population will occur in areas where local reproduction is sufficient to compensate for local mortality. In this sense, the realized niche may be larger than the fundamental niche. Consequently, the particular species assemblage occupying any local study site may consist of a mixture of source and sink populations and may be as much or more influenced by the type and proximity of other habitats a...
Reintroduction of griffon vulture to the Grands Causses began in 1981 when the first birds were released. Eight years later the colony has 74-78 individuals. The first birds, all adults from Spain, exhibited great difficulties in mastering soaring techniques but succeeded to establish a breeding colony as early as 1982. From 1985 all birds released were immatures and adapted more quickly to the wild. Among 34 birds lost or dead, electrocution and collision with power lines (11 birds) were the major cause of mortality. To feed and settle this new colony, three feeding sites were supplied with carcasses. The increase of the breeding group triggered a progressive colonization of the cliffs along the Tarn and the Jonte rivers. The overall home range used by the birds increased from 700 ha in 1982 to 3000 ha in 1989 when 25 pairs were breeding. Searching methods, size of foraging groups, the seasonal variation of foraging and feeding distances, as well as the use of different rising air currents are studied to understand how the birds explore their new environment. -from English summary
(1) The recolonization of an area in east-central England by sparrowhawks Accipiter nisus (L.) was studied after the local population had been eliminated, almost certainly by organochlorine pesticides. Over a 10-year period, nest numbers increased rapidly to begin with and then more slowly, with a mean rate of 21% per year. (2) Over the whole 10 years, the estimated annual survival of breeders was at least 76% for males and 74% for females, and mean productivity was 2.1 young per nest. Throughout, the breeding population contained a large proportion of first-year birds, with an overall figure of 35% of All male breeders and 25% of all female breeders. As the breeding population grew, young raised in the area tended to disperse ever greater distances from their natal sites. (3) Comparison of the increasing population with stable and decreasing populations in southern Scotland showed that differences in population trend were associated mainly with differences in the recruitment of new breeders (greatest in the increasing and lowest in the decreasing population) and in age of first breeding (earliest in the increasing and latest in the decreasing population). There were also differences in dispersal distances (shorter in the increasing population), and in the annual survival of breeders (greater in the increasing population). In contrast, differences in breeding success between areas were slight, and non-significant.
Brings together results from long-term studies of marked individuals and presents new information and new analyses of classic data sets. Important pointers emerge regarding the role of the individual in population processes and the factors which affect individual performance in the wild. The effects of age and experience on breeding success and survival prospects are assessed, and the question of senility is discussed. There are 6 sections on: short-lived hole nesters; short-lived open nesters; co-operative breeders; birds of prey; long-lived waterfowl and seabirds; and general issues. -from Publisher
Populations of Peromyscus leucopus (Raf.) were experimentally introduced onto two small, ecologically similar islands in the eastern Chesapeake Bay of Maryland, USA. Both islands already supported natural populations of Microtus pennsylvanicus (Ord.). Over a two year period Peromyscus dramatically increased in numbers on both islands, but the average rate of increase was more than twice as great on island A as on island B. Estimates from mark-recapture data indicate that the mean instantaneous death rate for Peromyscus was more than five times as high on island B as on island A. Interisland differences in vegetation, area, or food supply are inadequate to explain the observed differences in carrying capacity. The number of potential predators appears to be similar on both islands, but the number of refugia for mice is far greater on island A. Where both M. pennsylvanicus and P. leucopus are abundant, a negative correlation exists between the occurrence of the two species at a given trapping site, but no such relationship is evident at lower densities. Peromyscus presently seems to be well-established on both islands, but long-term monitoring is required to assess the ultimate success or failure of the introduced populations. /// Популяции Peromyscus leucopus (Raf.) экспериментальнлм путем были интродуцированы на 2 маленьких экологически сходных острова в восточной части Чизапкского залива в Мэриленде (США). На обоих осотровах были природные популяции Microtus pennsylvanicus (Ord). В течение 2-х лет численность Peromyscus сильно выросла на обоих островах, но скорость повышения численности на острове А была более чем вдвое выше, чем на острове Б. Определения методом мечения-повторного отлова показали, что средняя моментальная смертность ы Peromyscus была более чем в 5 раз выше на острове Б, чем на острове А. Различия плошади, растительного покрова или лишевых резервов между островами не адекватны различиям жизнемпосовности популяции. Число потенциальных врагов по-видимому одинакого на обоих островах, но число убежиш, для мышей на острове А гораздо бодше. Если M. pennsylvanicus и P. leucopus оба, имеют высокую численность, наблюдается отрицательная корреляция между встречаемоствю одоих выдов на территории отлова, но подовная взаимосвязь отсутствует при низкой численности. Peromyscus в настояшее время хорошо представлены на обоих островах. Предполагается осушествление долгосрочного мониторинга для определенея окончательного результата интородукции популяций животных.
(1) On territories where occupants were identified in successive years, 57% of cocks and 50% of hens had changed between one year and the next. These figures gave mean periods of residence on territories of 1.4 and 1.5 years respectively, but occasional cocks stayed on the same territories for up to 5 years, and occasional hens for up to 6 (in a 10-year study). Turnover was more rapid on poor territories than on good ones. It was due partly to mortality and partly to movement. (2) Of birds identified in the next year, 77% of cocks and 67% of hens were on the same territory, and the rest were on a different territory. The median distance moved by cocks which changed territory was 0.8 km (maximum distance 19 km), and by hens 1.5 km (maximum distance 27 km). The minimum distance between nesting territories was 0.4 km. (3) No difference in frequency of movement was noted between lowland and upland habitats, but birds which failed in their breeding the previous year more often changed territories than did birds which succeeded the previous year (significant only in hens). This tendency to move after a failure was especially marked in young birds, and became less marked with age. (4) Birds which changed territories showed a slight tendency to occupy a higher grade territory after their move than before it, but on average they did not breed any better at their next attempt than they had at the previous one, nor did birds which kept to the same territory. (5) In thirteen cases where mates kept together from year to year, they also stayed on the same territory, and in another case the pair moved to an adjacent territory in the same wood. In other cases, birds of either sex retained the same territory with a different mate, or changed both territory and mate, sometimes with the original partner alive and breeding elsewhere. Four years was the longest period in which a pair was found to stay together on the same territory. (6) On average, partners which had been together on the same territory the year before produced more young than did partners that were new to one another or to the territory. (7) With the possible exception of the sex difference in dispersal, the main findings of this study could be explained in terms of a single known response to food-supply.
We used data from a 12-yr study of dispersal and breeding success to investigate how female Red-winged Blackbirds (Agelaius phoeniceus) make decisions about movements between nests, both within and between years. Females were studied on eight separate marshes that were sufficiently close to permit inter-marsh movement. Our analyses showed that (1) a female's previous success affects her subsequent nesting decision, especially between years; (2) females exhibit strong marsh fidelity; and (3) the presence of familiar male neighbors affects female movement decisions. Little support was found for the ideas that females move in response to different types of nest predators, familiarity with current mates, or nesting success of other females on their marshes. Our results suggest that (1) there is more social constraint on changing territories and marshes, especially within breeding years, than previously suspected, and (2) although mate fidelity is relatively weak and unimportant, male @'neighborhoods@' or @'breeding groups@' affect female nesting success and, hence, influence movements.
(1) The number of recruits to the North Shields kittiwake colony in N.E. England (Coulson & Thomas 1985) increased from 1954 to 1967, but the proportion of first breeders decreased during that time. Increased mortality of the breeding birds or the provision of more sites increased recruitment. This implied that there was a pool of potential recruits from which the new recruits needed could be drawn. In most years there appeared to be a non-breeding reservoir. (2) About 11% of each cohort returned to breed in their natal colony. Immatures did not suffer the same variations in mortality as did adults; this finding is consistent with the premise of Coulson & Thomas (1985) that increased adult mortality associated with the decline in numbers in the late 1960s occurred prior to the breeding season. (3) The age of first breeding fell from 5 to 4 years in response to high adult mortality in the early 1970s; body weights and wing-lengths of male and female recruits diminished, but the body weights of male and female prospectors fluctuated little. (4) A model of colony growth is presented, based on the relationship between colony size and rate of increase in expanding colonies of British kittiwakes. Small colonies grow faster than large ones, and are proportionately more attractive to recruits. Small colonies cannot produce enough young during the first 70 years and are sustained by immigration. (5) The North Shields colony is not a closed system and is not currently growing; it is supported by immigration. There is a positive relationship between colony size and nesting density; colony growth appeared to be limited by the number of attractive sites in the dense centre of the colony. There were sites available on the periphery which were not used. The importance to breeding of the buffering effect of the pool of potential recruits is discussed.
Herring gulls originally colonized the Isle of May, Firth of Forth in 1907, which was followed by a period of progressive increase in numbers at 13% per annum. By 1970 there were c.13 000 breeding pairs. In 1972 the Nature Conservancy Council commenced annual culls which in 4 yr reduced the colony to a quarter of the previous density, but without radically altering the area of the island which was used for breeding. This paper considers the compensating factors which occur in herring gull which can mitigate against the effects of high natural or man-induced mortality. In particular, age of recruitment, condition of surviving adults, egg size and possibly emigration changed as the density of breeding birds decreased, each factor compensating for the increased adult mortality. -from Authors
Little is known of the life history of vultures. The reintroduction program of Griffon Vultures (Gyps fulvus fulvus) in the Causses (south of the Massif Central, France) and extensive monitoring by capture-mark-resighting of the released birds allowed us to obtain the first estimates of their survival. Adult survival rates are high (x̄ = 0.987 ± SE of 0.006). A release effect on adult survival was detected (only 0.743 ± 0.006 survival during the first year after release). Young born in the wild (less than three years old) had an annual survival rate of 0.858 ± 0.039. Mortality causes and erratic behavior of immature birds are considered in order to assess the effectiveness of this reintroduction program. Our results indicate that reintroductions of vultures and similar species should use adults that have bred in captivity within the target area rather than juveniles or immatures.
The successful conservation of any bird species, whether one which is threatened, of economic value or of pest status, requires knowledge of both its population biology and its ecological requirements. The 30 papers on this theme that have emerged from the 1st International Symposium organised by the Station Biologique de la Tour du Valat (December 1988) are here presented in sections which consider: the comparative approach; estimating the parameters; the species approach; further issues (eg migration and parasitism); and species management. See 92L/02882-02899, 02914, 02915, 02919, 02920, 03019, 03044, 03119, 03209-03212 and 03218. -P.J.Jarvis
Colonial waterbirds are an important natural resource highly valued by many people in Canada and the United States. The habit of nesting often in large groups makes these birds especially susceptible to problems, such as human disturbance, predation, severe weather events, and competition for nesting habitat. They, like all birds, also face threats from habitat degradation, loss and contamination of their environments, and changes in food webs. Management strategies to deal with these problems include habitat preservation and restoration, the elimination of toxic chemicals from the environment, reduction of predation, competition, and disturbance at nesting sites, reintroduction of species to nesting sites from which they have been eliminated, and fisheries management from a multispecies ecosystem perspective. Techniques are discussed and examples provided. A few colonial waterbird species have increased greatly in numbers and now pose problems for other bird species or are in conflict with people. Management is also involved in the control of such problem birds. Strategies include habitat modifications and scaring or killing problem birds. There is a continuing need for information and research to allow appropriate management to be applied. Regular surveys and inventories are necessary on a regional basis to detect trends in population status and to minimize and mitigate conflicts with human activities. Studies of population demography are needed for species declining in numbers, and research into species ecology is often necessary before appropriate management can be applied. Additional techniques to reduce conflicts between birds and humans are also needed. Human activities are likely a major limiting factor for some species, and, conversely, humans are largely responsible for the increases of several species that have become problems. Continued education of the public and of conservation management agencies to the role and importance of colonial waterbirds is important. Many species are likely to continue to suffer from gradual incremental loss and degradation of habitats, and a conservation strategy for the protection of these birds throughout North America is recommended.
The project of re-introduction of the Bearded Vulture into the Alps (WWF/IUCN -Project 1657/78 and Frankfurter Zoological Society Project No. 832/78) was started in 1978 with the aim of establishing a breeding stock for future releases. With the generous help of many European zoos it was possible to form 12 breeding pairs. In 19 8 6 the first release took place in the Austrian Alps with 4 birds bred in captivity in the same year. One had to be taken back for future use within the breeding stock after an accident. The remaining 3 are still returning occasionally to the release site, where 2 young of 1987 were set out this sum-mer. Simultaneously another release site in France was furnished with 3 birds. All 5 vultures have left their release ledges making their first flights.
Environmental enrichment is an increasingly popular method for improving the well-being of animals in zoos. Research has shown that simple and eminently practical changes to the way zoo animals are kept can have highly beneficial effects on their behaviour and physiology. Carlstead, Seidensticker and Baldwin (1991), for example, found that providing bears with hidden food and manipulable objects greatly increased activity and exploration at the expense of repetitive stereotyped behaviours. Similarly Kastelein and Wiepkema (1989) observed that a walrus provided with realistic foraging opportunities, namely searching for food items amongst concrete blocks, greatly reduced the amount of stereotyped swimming. Providing a kinkajou with food that required exploratory and manipulatory behaviour, by hanging whole fruit from branches as an alternative to chopped fruit in a bowl, resulted in greatly increased rates of locomotion, exploration and foraging behaviour which corresponded with reductions in the levels of stereo-typed behaviour (Shepherdson, Brownback and Tinkler, 1990). These and other successful techniques share an important characteristic: they restore to the captive animal the contingency between the performance of behaviour (foraging for example) and the appropriate consequences (such as finding food).
At sites in upstate New York, 44% of males and 25% of females resident in one year returned in one or more subsequent years. There were more nests built, eggs laid, eggs hatched, and young fledged in territories of returning males in this polygynous species than in territories of males that did not return in subsequent years. For females that returned, the number of eggs hatched, young fledged, young fledged on last nest attempt, and young fledged per egg laid, were higher than for females that did not return. Male and female bobolinks used information on their breeding success in one year to influence their choice of breeding site in the next year. -from Authors
Among Western Palaearctic birds, range expansion is more commonly observed in families with low proportions of long-distance migrants than among generally migratory families. Migrants are also disproportionately scarce in the Irish avifauna, compared with that of Britain, and scarcer among colonists of Britain than among long-established species. Colonization attempts in southeast England and in Scotland have more frequently resulted in establishment by the invader than have attempts in areas more remote from the European mainland; in several cases, these attempts have followed a history of range expansion and/or population increase in the source areas. Successful colonists lay more eggs each season, on average, than failed colonists; this difference is due, in part, to larger clutches and in part to more clutches per season. The failure of migrants to make successful invaders is attributed to their inability to compete for resources, especially habitat, in the face of competition from year-round residents. The findings otherwise agree well with predictions of the MacArthur-Wilson theory of island colonization.
1. Settlement in a new environment is a key phase in effective dispersal. We investigated this phase in the common lizard (Lacerta vivipara Jacquin) by an experimental introduction of known individuals. 2. Introducing lizards in an already occupied environment revealed a prior-residence advantage and some differences in the ability of individuals to face a new environment under conditions of high intraspecific competition. 3. Transplanted individuals (TI) died in larger numbers than resident ones (RI) immediately after the introduction, except for juveniles. this prior-residence advantage could arise from the difference of familiarity with the local environment or from a dominant behaviour of RI on TI. 4. TI which survived the first winter after the introduction survived better than RI afterwards. However, surviving TI females paid a cost in their reproduction. 5. Surviving TI were not a random subset of the initial sample: smaller adult males and leaner adult females were selected. These selective responses arose from the transplantation since they were not observed in non-manipulated populations. 6. A comparison of characteristics between natural transient or immigrant individuals and TI survivors revealed: (i) TI male and yearling survivors may have been transients or immigrants in their site of origin; (ii) TI adult female survivors were not transients nor immigrants in their site of origin. The latter result questions the use of introduction experiments to test dispersal ability. Strictly. introduction experiments only test settlement ability.
(1) The breeding success and timing of laying of manx shearwaters breeding on Skokholm Island, Wales, are discussed. (2) Newly formed pairs have a lower hatching success (66.2%) than established pairs (79.1%). This is due to the fact that new pairs include birds without prior breeding experience and not to the newly formed pair bond per se. (3) When forming new pairs experienced breeding birds tend to mate with other experienced breeding birds rather than new breeders. (4) Divorce and burrow movement are both more likely after breeding failure than after success. (5) The timing of laying and the size of eggs laid are very constant from year to year, both for the population as a whole and for individual females. (6) The relationship of laying date and egg size to female age is described. (7) It is suggested that birds do not lay earlier than they do because, early in the season, the food supply would be inadequate to enable the adults to maintain continuous incubation. (8) Circumstantial evidence is presented suggesting that conditions for incubation improve during the incubation period.
Houston, D. C. 1974. Mortality of the Cape Vulture. Ostrich 45: 57–62.An attempt was made to analyse the ringing returns of the Cape Vulture Gyps coprotheres from Transvaal colonies. Although it is not yet possible to determine annual mortality rates, some conclusions can be deduced from the results. Mortality during the early age classes is high and is over 500; during the first year. Mortality must decline rapidly with age, but it seems probable that recruitment to the breeding population at these colonies is insufficient to balance adult mortality and the population may be declining.
The breeding season of two species of griffon vultures are described. Rüppell's Griffon Vulture lays 2–3 months earlier than the White-backed Griffon. Young birds were hand-reared to determine their food requirements during growth; these estimates were combined with the food requirements of adult birds to make an estimate of the amount of food a parent bird needs to obtain when it is rearing young. The amount of food actually obtained by a group of birds was recorded from the size of the crops of birds returning to the breeding colony in the afternoon. The comparison of the estimates of the food obtained and the food required through the breeding season suggested that there may be a period during rearing when there was insufficient food available to satisfy the food requirements of both chick and adult. Chicks were found to have a very high survival rate and were probably receiving sufficient food. Presumably adult birds were not therefore receiving sufficient food, and the examination of a sample of adult birds for body condition through the breeding season showed a clear decline in their fat deposits. It was considered that in both species, breeding was timed so that the young left the nest at a period in the year when food conditions were good and the young birds could feed with little competition from adults. The parent birds therefore had to rear young during a season in the year when food conditions were not always adequate and they had to rely on utilising fat reserves. The food conditions for vultures during this study were probably favourable and during years of food shortage breeding may become impossible, or restricted to the most aggressive and dominant individuals.
Random dispersal direction is assumed in all current metapopulation models. This assumption is called into question by recent experiments demonstrating that some species disperse preferentially to sites occupied by conspecifies. We incorporate conspecific attraction into two metapopulation models which differ in type of dispersal, the Levins model and a two-dimensional stepping-stone model. In both models, conspecific attraction lowers the proportion of occupied habitat patches within a metapopulation at equilibrium.
Breeding site fidelity is high in willow ptarmigan: only 9% of males and 31% of females switched territories between years. Unpaired males were more likely to switch territories than paired males. For paired males, survival of their previous partner and reproductive success in year x did not influence probability of switching in year x+1. A female was more likely to switch territories if her previous partner disappeared. If her partner returned, she had a higher probability of switching if she did not produce chicks the previous year. Most hens moved to the territories of older males, although hens paired with unfamiliar older males did not have higher reproductive success than those paired with yearlings. Individuals that paired with their previous partner laid earlier and produced heavier chicks than those paired with unfamiliar partners. Excluding birds paired with familiar partners, survival and reproductive success in year x+1 was similar for males and females that did or did not switch territories. Males had a higher probability of producing chicks after switching than before, but females were more likely to lose their clutch after switching. For both sexes, birds that switched territories were as successful as the birds that replaced them on their former territories. We conclude that high site fidelity in willow ptarmigan is maintained because of the benefits of pairing with a familiar partner.
The population structure of the spruce grouse (Canachites canadensis) was studied in the Adirondack Mountains of New York, U.S.A. Twenty-five isolated habitat patches exist and are occupied by spruce grouse, with 7 suitable but unoccupied patches existing at the periphery of the range. The regional distribution and abundance of spruce grouse is correlated with the amount of lowland coniferous forest habitat. Unoccupied patches were significantly smaller and significantly farther from occupied patches than were other occupied patches. For all patches, as distance from the nearest occupied patch increased, the percent of occupied patches decreased linearly. I incorporated birth and death rates for spruce grouse into the MacArthur-Wilson survivorship model which closely predicted the proportion of occupied patches for an average population density (2.8 spruce grouse/100ha). For the same demographic parameters, extinction times were calculated which indicate that the 15 habitat patches of a carrying capacity of 3 female spruce grouse (100 ha) would have an average extinction time of less than 6 years. This in part accounts for the high proportion of these patches which are unoccupied. Extinctions and recolonizations of patches were observed during the study. The patterns of patch occupancy can partially be predicted based on their size, spatial arrangement, and the demographic characteristics of the spruce grouse.
Cape vultures Gyps coprotheres in the southwestern Cape Province feed exclusively on sheep carcasses, within a limited foraging area. The size and shape of the foraging range was determined by means of a postal survey and confirmed by a radio-tracking study. The quantity of food available within the range, while seasonally variable, was estimated to exceed the colony's requirements. Data pertaining to daily feeding forays of individuals, monthly foraging patterns of the colony and the growth of nestlings indicated no seasonal shortages in the amount of food obtained. The colony remains susceptible to the effects of poisons used in the area; levels of contaminants recorded in most eggs are considered low.