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The ''bug-egg'' and two dummy eggs in a common tern Sterna hirundo nest, combined with a nest antenna to identify the breeding adult marked with a transponder (photo C.C. Voigt)
Source publication
We describe a non-invasive technique to obtain blood samples from incubating birds without trapping and handling. A larval
instar of the blood-sucking bug Dipetalogaster maximus (Heteroptera) was put in a hollowed artificial egg which was placed in a common tern (Sterna hirundo) nest. A gauze-covered hole in the egg allowed the bug to draw blood fr...
Citations
... For blood sampling, we used starved kissing bugs (Dipetalogaster maxima; Becker et al., 2006). We inserted one or two third larval instars into an artificial hollow egg, closely resembling a real common tern egg in size and colour. ...
Mercury levels in the environment are increasing, such that they are also expected to accumulate in toppredators, but individual-based longitudinal studies required to investigate this are rare. Between 2017 and 2023, we therefore collected 1314 blood samples from 588 individual common terns (Sterna hirundo) to examine how total blood mercury concentration changed with age, and whether this differed between the sexes. Blood mercury concentrations were highly variable, but all exceeded toxicity thresholds above which adverse health effects were previously observed. A global model showed blood mercury to be higher in older birds of both sexes. Subsequent models partitioning the age effect into within- and among-individual components revealed a linear within-individual accumulation with age in females, and a decelerating within-individual accumulation with age in males. Time spent at the (particularly contaminated) breeding grounds prior to sampling, as well as egg laying in females, were also found to affect mercury concentrations. As such, our study provides evidence that male and female common terns differentially accumulate mercury in their blood as they grow older and calls for further studies of the underlying mechanisms as well as its consequences for fitness components, such as reproductive
performance and survival.
... use of wildlife cameras, acoustic monitoring; Buxton et al., 2018), techniques that involve non-interference or minimal interference with the animal have been developed for the collection of physiological markers [e.g. faeces collection or blood collection using blood-sucking bugs (Millspaugh & Washburn, 2004;Becker et al., 2006)]. Such approaches conform well with the current trend favouring non-invasive over invasive measurements for wild animals (Zemanova, 2020). ...
Affective states, such as emotions, are presumably widespread across the animal kingdom because of the adaptive advantages they are supposed to confer. However, the study of the affective states of animals has thus far been largely restricted to enhancing the welfare of animals managed by humans in non-natural contexts. Given the diversity of wild animals and the variable conditions they can experience, extending studies on animal affective states to the natural conditions that most animals experience will allow us to broaden and deepen our general understanding of animal welfare. Yet, this same diversity makes examining animal welfare in the wild highly challenging. There is therefore a need for unifying theoretical frameworks and methodological approaches that can guide researchers keen to engage in this promising research area. The aim of this article is to help advance this important research area by highlighting the central relationship between physiology and animal welfare and rectify its apparent oversight, as revealed by the current scientific literature on wild animals. Moreover, this article emphasises the advantages of including physiological markers to assess animal welfare in the wild (e.g. objectivity, comparability, condition range, temporality), as well as their concomitant limitations (e.g. only access to peripheral physiological markers with complex relationships with affective states). Best-practice recommendations (e.g. replication and multifactorial approaches) are also provided to allow physiological markers to be used most effectively and appropriately when assessing the welfare of animals in their natural habitat. This review seeks to provide the foundation for a new and distinct research area with a vast theoretical and applied potential: wild animal welfare physiology.
... Blood of breeding common terns was sampled in the years 2013, 2014 and 2017 using larval stages of the bloodsucking bug Dipetalogaster maximus. Within 9-14 days of clutch completion of each focal bird in each year, bugs were placed into dummy eggs with holes and placed in the nests (Becker et al., 2006;Arnold et al., 2008;Bichet et al., 2019). After 20-30 min of incubation by the focal bird, "bug eggs" were collected and the focal birds' blood, sucked by the bug, was removed from the bugs' abdomen using a syringe. ...
Senescence, an age-related decline in survival and/or reproductive performance, occurs in species across the tree of life. Molecular mechanisms underlying this within-individual phenomenon are still largely unknown, but DNA methylation changes with age are among the candidates. Using a longitudinal approach, we investigated age-specific changes in autosomal methylation of common terns, relatively long-lived migratory seabirds known to show senescence. We collected blood at 1-, 3- and/or 4-year intervals, extracted DNA from the erythrocytes and estimated autosomal DNA methylation by mapping Reduced Representative Bisulfite Sequencing reads to a de novo assembled reference genome. We found autosomal methylation levels to decrease with age within females, but not males, and no evidence for selective (dis)appearance of birds of either sex in relation to their methylation level. Moreover, although we found positions in the genome to consistently vary in their methylation levels, individuals did not show such strong consistent variance. These results pave the way for studies at the level of genome features or specific positions, which should elucidate the functional consequences of the patterns observed, and how they translate to the ageing phenotype.
... In total, we collected 483 samples from terns and 140 samples from gulls (Table 1). Blood samples were obtained from adult breeders, either via puncture of the ulnar vein with a disposable needle (following capture) or non-invasively, using artificial eggs with bloodsucking bugs (Dipetalogaster maximus) (for common terns from Wilhelmshaven, details in Becker et al., 2006). This method allows to obtain blood samples without any negative impact on genetic material (DNA), which can be used as a high-quality source for molecular analyses (e.g. ...
Haemoparasites represent a diverse group of vector-borne parasites that infect a wide range of vertebrate hosts. In birds, haemoparasite infection rates may be associated with various ecological and life history traits, including habitat choice, colony size and migration distance. Here, we molecularly assessed prevalence of three main haemoparasite genera (Plasmodium, Haemoproteus and Leucocytozoon) in two bird species with different habitat preferences and migratory behaviour: black-headed gulls (Chroicocephalus ridibundus) and common terns (Sterna hirundo). We found that gulls showed a much higher prevalence and diversity of Plasmodium or Haemoproteus (ca. 60% of individuals infected) than terns (zero prevalence). Prevalence of Leucocytozoon was low in both species (<3%). The differences in haemoparasite prevalences may be primarily driven by varying vector encounter rate resulting from different habitat preferences, as black-headed gulls mainly use vector-rich vegetated freshwater habitats, whereas common terns often use vector-poor coastal and brackish habitats. Since common terns migrate further than black-headed gulls, our results did not provide support for an association between haemoparasite prevalence and migratory distance. In gulls, we found a negative association between colony size and infection rates, suggestive of an ideal despotic distribution, and phylogenetic analyses of detected haemoparasite lineages provided evidence for higher host specificity in Haemoproteus than Plasmodium. Our results suggest that the preference for coastal areas and less vegetated habitats in terns may reduce haemoparasite infection rates compared to other larids, regardless of their migratory distance, emphasizing the role of ecological niches in parasite exposure.
... Blood samples were collected from breeders of both sexes in 2007, 2008, 2013, 2014 and 2016. To collect a sample from a specific bird, a larval instar of the blood-sucking bug Dipetalogaster maximus was placed in a hollow artificial egg, which was temporarily placed in the nest of the target bird during incubation (for details see Becker et al., 2006). Visual observation combined with the antenna system was used to confirm the continuous presence of the target bird. ...
Telomeres are protective caps at the end of eukaryotic chromosomes that shorten with age and in response to stressful or resource‐demanding conditions. Their length predicts individual health and lifespan across a wide range of animals, but whether the observed positive association between telomere length and lifespan is environmentally induced, or set at conception due to a shared genetic basis, has not been tested in wild animals. We applied quantitative genetic ‘animal models’ to longitudinal telomere measurements collected over a 10‐year period from individuals of a wild seabird (common tern; Sterna hirundo) with known pedigree. We found no variation in telomere shortening with age among individuals at the phenotypic and genetic level, and only a small permanent environmental effect on adult telomere length. Instead, we found telomere length to be highly heritable and strongly positively genetically correlated with lifespan. Such heritable differences between individuals that are set at conception may present a hitherto underappreciated component of variation in somatic state.
... As an alternative to blood sampling, the use of haematophagous Heteroptera bugs has been suggested in ornithological research to non-invasively retrieve blood from individuals, e.g. for hormonal or for pathogen detection studies [2,4,5,84]. It has also been successfully used in primates [90] and rabbits for hormonal studies [49,92], as well as rabies serology in mice, under laboratory conditions [94]. ...
Most vertebrates host a wide variety of haematophagous parasites, which may play an important role in the transmission of vector-borne microorganisms to hosts. Surveillance is usually performed by collecting blood and/or tissue samples from vertebrate hosts. There are multiple methods to obtain samples, which can be stored for decades if properly kept. However, blood sampling is considered an invasive method and may possibly be harmful to the sampled individual. In this study, we investigated the use of ectoparasites as a tool to acquire molecular information about the presence and diversity of infectious microorganism in host populations. We tested the presence of three distinct vector-borne microorganisms in both bat blood and bat flies: Bartonella bacteria, malaria-like Polychromophilus sp. (Apicomplexa), and Trypanosoma sp. (Kinetoplastea). We detected the presence of these microorganisms both in bats and in their bat flies, with the exception of Trypanosoma sp. in South African bat flies. Additionally, we found Bartonella sp. in bat flies from one population in Spain, suggesting its presence in the host population even if not detected in bats. Bartonella and Polychromophilus infection showed the highest prevalence in both bat and bat fly populations. Single, co- and triple infections were also frequently present in both. We highlight the use of haematophagous ectoparasites to study the presence of infectious microorganism in host blood and its use as an alternative, less invasive sampling method.
... To evaluate the seroprevalence of T. gondii in European Association of Zoos and Aquaria (EAZA) zoos, a minimally invasive technique using reduviid bugs, which has been described by various authors, can be a valuable alternative to conventional blood sampling [40][41][42][43][44][45][46]. Reports of the use of reduviid bugs were found as early as in 1971, when they were tested as an alternative bleeding method for geckos instead of the common practice to cut the tip of tail off. ...
Background:
Toxoplasma gondii infections and cases of clinical toxoplasmosis have been recorded in zoo animals. Wild felids in human care can serve as definitive hosts that shed oocysts, but also as intermediate hosts for the parasite. Some felid species, such as the Pallas's cat (Otocolobus manul) or sand cat (Felis margarita), may suffer from clinically apparent toxoplasmosis. In the present study, our main aim was to assess risk factors for T. gondii infections in small exotic felids.
Methods:
A seroepidemiological study was conducted using the reduviid bug Dipetalogaster maxima for blood sample collection, a method previously evaluated on domestic cats. A total of 336 samples from 17 felid species were collected in 51 institutions, 48 of which were within Europe and the remaining three in the Middle East (United Arabic Emirates and Qatar). These samples were analyzed for T. gondii antibodies by immunoblotting and an immunofluorescent antibody test. Potential risk factors in zoos for seropositivity regarding T. gondii among members of the European Association of Zoos and Aquaria (EAZA) were evaluated using a questionnaire and individual data from the Zoological Information Management System (ZIMS).
Results:
The sampled felids showed an overall seroprevalence for T. gondii of 63%. The risk factor study including data of 311 small exotic cats of 10 species resulted in a final generalized linear mixed model comprised of five variables: the likelihood of seropositivity increased statistically significantly with "Age", while feeding "Cattle: frozen" relative to "Cattle: fresh", "Outdoor housing fenced in on all sides", "Mesh size 2-5 cm" relative to "Mesh size > 5 cm" and "Wearing gloves: yes" had statistically significant protective effects.
Conclusions:
Wild felids, including endangered species, kept in human care in European and Middle Eastern institutions, are widely exposed to T. gondii. Risk factor analysis revealed that feeding previously frozen tissues, keeping animals in enclosures that are fenced on all sides using fences with small mesh sizes, and wearing gloves when working inside enclosures seem to be the most relevant protective measures to prevent T. gondii infections in these animals .
... With the aim of evaluate the relationship between the trophic strategy and the hormonal values, we compared two identified groups of breeders, one There was no negative impact of the bug method on behavior or breeding success of the terns (Becker et al. 2006). This sampling method was successfully validated in Common Terns for prolactin (Riechert et al. 2012) and corticosterone (Arnold et al. 2008). ...
... To minimize the possibility of diurnal variation in PRL and CORT values, all blood samples were taken in the early morning between 5 and 10 am. For blood sampling of breeders, we used starved third stage larvae of blood-sucking bugs Dipetalogaster maximus in hollow eggs (Becker et al. 2006, Arnold et al. 2008). The colony is accustomed to researcher activities, and adults settle down immediately after a person had passed their clutch. ...
... The colony is accustomed to researcher activities, and adults settle down immediately after a person had passed their clutch. Every morning before sampling, we equipped all focal clutches with antennas, and after the target bird was identified, we replaced the whole clutch with dummy eggs, one containing the bug (Becker et al. 2006). The Common Tern eggs were kept warm and safe in a box during the sampling procedure. ...
Kleptoparasitism is a well-known foraging strategy used by many colonial seabirds. The expression of this behavior can reduce the cost of foraging during the breeding season and ultimately this can reflected in physiological parameters. Here we analyzed the relationship between the trophic strategy of Common Terns Sterna hirundo and two hormones, that are known to be involved in decision-making during the reproductive cycle and foraging activities: corticosterone (CORT) and prolactin (PRL). The study was conducted during the breeding seasons 2012–2014 at the Banter See colony in northern Germany where individuals with different foraging strategies were identified and monitored since 2008. We studied the concentration of hormones in two groups of birds: kleptoparasitic individuals i.e. individuals who steal the food captured by another individual, and honest individuals i.e. individuals who obtain the food on their own. Blood samples were obtained during the mid-incubation period using a non-invasive technique. Both hormones showed no significant relationship to each other. CORT concentration was similar in both groups of birds. However, the concentration of PRL was higher in parasitic than honest individuals in 2014. In addition, CORT modelling indicated a year effect (higher CORT in 2013), and PRL modelling indicated a significant effect of year (higher PRL in 2012) and a significant interaction between year and the trophic strategy in 2014. The results show no clear relationship between the feeding strategy and studied corticosterone and prolactin levels.
... Hematophagous bugs are easy to handle and transport to the field, they have a small proboscis and can perforate micro-vessels, releasing anticoagulants into the blood after ingestion, minimizing pain, bruising and allergic reactions, all of which are advantages for blood sampling of animals [21]. The use of Triatominae insects contained in fake eggs, known as the 'bug-egg' method, has been developed a decade ago to collect blood from incubating ground-nesting common terns (Sterna hirundo) [22][23][24]. This method was also applied to obtain samples from incubating common swifts (Apus apus) [25], and, more recently, from medium-sized raptors, such as Montagu's harriers (Circus pygargus) [26] and Eurasian kestrels (Falco tinnunculus) [27]. ...
... This species of insect was chosen because it preferably feeds on birds and also because laboratory-bred nymphs are readily available in several places of the Neotropical region. Fiberglass fake eggs [22] were manufactured to resemble cattle egret eggs in color and size (45 mm length, 33 mm width) ( Fig 1A); holes measuring 5 mm Ø spaced at 5-mm intervals were made along the circumference of eggs so that the bugs could project their proboscis out without escaping. One insect was placed inside each fake egg immediately prior to use, and the two halves of the egg were carefully closed with a bolt and nut (Fig 1B), without harming the bugs. ...
... Inferences were made either by applying the parental allocation approach [57] or the multiple methods approach in the absence of parental information [11]. [22], the 'bug-egg' method has been mostly applied to collect samples from the common tern [22][23][24][64][65][66][67][68] and common swift [25], which are small birds with a markedly different biology from colonial egrets. More recently, this method was applied to sample adults of mediumsized raptors, such as the ground-nesting Montagu's harrier [26] and the cavity-nesting Eurasian kestrel [27]. ...
Colonial waterbirds such as herons, egrets and spoonbills exhibit ecological characteristics that could have promoted the evolution of conspecific brood parasitism and extra-pair copulation. However, an adequate characterization of the genetic mating systems of this avian group has been hindered by the lack of samples of elusive candidate parents which precluded conducting conventional parentage allocation tests. Here, we investigate the genetic mating system of the invasive cattle egret using hematophagous insects contained in fake eggs to collect blood from incubating adults in a wild breeding colony. We tested a protocol with a previously unused Neotropical Triatominae, Panstrongylus megistus, obtained blood samples from males and females in 31 nests built on trees, drew blood from 89 nestlings at those nests, and genotyped all samples at 14 microsatellite loci, including six new species-specific loci. We comparatively addressed the performance of parentage allocation versus kinship classification of nestlings to infer the genetic mating system of cattle egrets. In line with previous behavioral observations, we found evidence in support of a non-monogamous genetic mating system, including extra-pair paternity (EPP) and conspecific brood parasitism (CBP). Parentage allocation tests detected a higher percentage of nests with alternative reproductive tactics (EPP: 61.7%; CBP: 64.5%) than the kinship classification method (EPP: 50.0%; CBP: 43.3%). Overall, these results indicate that rates of alternative reproductive tactics inferred in the absence of parental genetic information could be underestimated and should be interpreted with caution. This study highlights the importance of incorporating samples from candidate parents to adequately determine the genetic mating system of a species. We expand knowledge on the reproductive tactics of colonial waterbirds, contributing novel data on the genetic mating system of the cattle egret, valuable for the design of management strategies for this invasive bird.
... Blood samples were taken minimally invasive by using blood-sucking bugs (Dipetalogaster maxima) in hollow eggs (Becker et al. 2006). Sampling took place in the early morning between 5 and 9 a.m. to minimize diurnal variation in hormone levels. ...
Biparental care is found across taxa, but sex-specific contributions vary greatly both between and within species. Factors underlying intraspecific variation may include the phase of the reproductive cycle and sex-specific duties resulting in physiological or environmental constraints that differ between the sexes. For pair members to achieve high breeding success while maintaining good condition, parental duties should be well coordinated between mates. Avian breeding behavior is mediated by hormones such as prolactin and corticosterone, which link the internal and environmental parameters of individuals and regulate resource allocation. Using automated recording at the nest, we analyzed parental attendance by Common Terns (Sterna hirundo) in relation to sex, reproductive phase (incubation, chick rearing), time of day, breeding experience, and hormone levels, and related it to reproductive success. Nest attendance of females exceeded that of males, especially at night and during chick rearing. Greater breeding experience was linked to increased attendance at night by males and during incubation by females. Parental nest attendance during incubation was not related to duration of the incubation phase, nor to hatching success. However, fledging success increased with greater parental attendance during the early chick rearing period, reflecting a higher vulnerability of small chicks to mortality compared with eggs. Prolactin values of male parents were significantly lower during chick rearing than incubation and in comparison with values of female parents. Female breeding experience was positively correlated with increased hormone values during chick rearing. Male attendance during chick rearing covaried with hormone levels: moderately increased corticosterone could support males in their new role as feeders by facilitating high activity and foraging effort, whereas lowered prolactin might indicate less contact with chicks and reduced body weight. We show that Common Terns exhibit a flexible system of sex-specific parental care during incubation and chick rearing, reflected in hormone levels, which mediate breeding behavior and ultimately affect reproductive success.
