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Primate Ecology and Social Organization
Abstract
Estimates of body weight, group size, home range size, day range length, socionomic sex ratio and sexual dimorphism are compared between 100 primate species, allocated to seven ecological categories. As would be predicted on energetic grounds, home range size and day range length are positively related to group weight and are greater in frugivores than in folivores; population density is negatively related to body weight; and group size is positively related to body weight. The adaptive significance of Variation in body size, sexual dimorphism and socionomic sex ratio is also discussed.
... For example, this cluster included early studies by Crook and Gartlan (1966) relating behavioural traits to habitats, and by Jolly (1966) linking social behaviour to intelligence from a theoretical perspective. This cluster also included studies on the adaptive significance of multiple morphological, ecological, and social traits (Clutton-Brock & Harvey 1977) and life-history traits (van Schaik 1983, Harvey & Clutton-Brock 1985, Promislow & Harvey 1990). Other studies were focused on the evolutionary relationship between testicle size and body mass (Kenagy & Trombulak 1986) and mating systems (Harcourt et al. 1981), and between brain size and foraging patterns (Milton 1981) and metabolism (Martin 1981). ...
... There were also studies relating energetic demands to home range size (Harvey & Clutton-Brock 1981), and allometric studies of the canine size (Leutenegger & Kelly 1977, Harvey et al. 1978) and the foetus (Leutenegger 1973). The most cited study in this cluster was by Clutton-Brock and Harvey (1977), with 743 citations, followed by Harcourt et al. (1981) with 681, and Promislow and Harvey (1990) with 679 citations. However, Ford and Davis (1992) had the highest total link strength, with 158 links (Appendices S6 and S7). ...
... Their works, in turn, led to an unprecedented enrichment of our knowledge of primate social relationships (e.g. Goodall 1966, Clutton-Brock & Harvey 1977, Wrangham 1979, 1980. The 1970s consolidated many paradigms shifts in the ecological and evolutionary theories of the preceding decades through technical advances in research design, data collection, and analysis (McIntosh 1985). ...
Given the position of humans in the tree of life, comparative research on non‐human primates has attracted the interest of researchers in biology, medical sciences, anthropology, psychology, and sociology. Covariation of species' phenotypes has been of particular interest.
Learning from the historical development of comparative research with primates should thus be particularly valuable for evolutionary ecology and to improve understanding of phenotypic integration and diversity. Such learning would also help identify knowledge gaps, disputed questions, and new avenues of both basic and applied research in relation to the evolution of primate features and the conservation of our close relatives.
We conducted a historical assessment through a non‐systematic review and a systematic review, focusing on how the integration of different research lines in evolutionary ecology focused on primate phenotypic covariation unfolded throughout the 20th Century. The non‐systematic review allowed us to reconstruct the history of the discipline from its earliest origins, when bibliometric assessments were more limited in scope, and to identify the most appropriate keywords for the systematic review. We employed a standard protocol for the systematic review, applying two complementary analyses: co‐occurrence of keywords and bibliographic coupling of references. These analyses described the development of the conceptual and intellectual structures of comparative primatology from 1966 to 2020.
By identifying the most influential researchers and concept interrelations, we highlight primate phenotypes critical for the development of the discipline (in particular, brain and body sizes and behavioural patterns), showcasing the reach of these investigations for evolutionary ecology. Overall, our findings emphasise the crucial role that comparative primatology has played in developing the study of phenotypic integration and the very onset of phylogenetic comparative methods.
... Neither criterion is based on sufficient information to determine rates of dimorphism: body mass difference thresholds are both arbitrary and inconsistent, and an average body mass ratio >1 across species can indicate either more frequent dimorphism or more extreme dimorphism in one sex than the other. In addition, research on SSD in mammals has tended to focus on a few taxa, namely artiodactyls, carnivores (especially pinnipeds), and primates 8,[17][18][19][20][21] : clades with high rates of male-biased SSD 22 . However, most mammals, by far, are rodents and bats 23 , which are often under-represented in studies of SSD. ...
... Larger males were the norm for several of the less species-rich orders, while several others were evenly divided between larger males and monomorphism, and larger females were the norm for Lagomorpha (Fig. 2, Supplementary Fig. 2). Notably, the orders that had the most prevalent male-biased dimorphism included Artiodactyla, Carnivora, and Primates: the orders that dominate the SSD literature for mammals 8,[17][18][19][20][21] . Differences in rates of SSD at the family level were also evident, indicating that weighting our estimates based on species richness in each family was important. ...
Sexual size dimorphism has motivated a large body of research on mammalian mating strategies and sexual selection. Despite some contrary evidence, the narrative that larger males are the norm in mammals—upheld since Darwin’s Descent of Man—still dominates today, supported by meta-analyses that use coarse measures of dimorphism and taxonomically-biased sampling. With newly-available datasets and primary sources reporting sex-segregated means and variances in adult body mass, we estimate statistically-determined rates of sexual size dimorphism in mammals, sampling taxa by their species richness at the family level. Our analyses of wild, non-provisioned populations representing >400 species indicate that although males tend to be larger than females when dimorphism occurs, males are not larger in most mammal species, suggesting a need to revisit other assumptions in sexual selection research.
... Long-term monitoring of the fitness of a population is fundamental as it is affected by slow-changing environmental factors [11]. For instance, the social structure of a social species reflects the trade-off between the costs and benefits of being alone or part of a group based on resource type and allocation [12,13], intra-specific competition, and predation [14,15]. Both environmental factors and the social structure of a population affect its demographic and reproductive parameters and, consequently, its long-term viability [7,[16][17][18]. ...
... and the proportion of the frame filled by the fin (1 = greater than 5%, 5 = less than 1%). The sum of the five scores would result in poor (>12), average (10)(11)(12), or excellent (6-9) picture quality. In addition, further following Urian et al [88], the distinctiveness of the dorsal fin was scored based on how many marks, notches, and scars were present, and their size. ...
It is challenging to collect robust, long-term datasets to properly monitor the viability and social structure of large, long-lived animals, especially marine mammals. The present study used a unique long-term dataset to investigate the population parameters and social structure of a poorly studied population of bottlenose dolphins (Tursiops sp.) in southern Port Phillip Bay, south-eastern Australia. Photo-identification images have been collected between 2012-2022 both opportunistically and following a protocol by patrons, staff, and volunteers of ecotourism companies using their vessels as platforms. The resulting large dataset was available to be processed through the online platform Flukebook and used in capture recapture models to estimate abundance and demographic parameters. In addition, the social structure of the population and the reproductive parameters were investigated. The marked adult population abundance (45.2 ± 2.7 individuals) was found to be stable over the last decade and the calving rate ranged between 0.06-0.19 new calves per identified individuals per year, while the inter-birth interval was 3.7 ± 0.8 years. Social analysis suggested the population has a fission-fusion structure with no apparent clusters. The stability of the population over the study period suggests no deleterious effect of anthropogenic or environmental factors during the last decade. This study is the outcome of the effort of the ecotourism organisations and the results obtained, along with their similarity to those of other dolphin populations worldwide, highlight the importance of such data sources for long-term information that would otherwise be too expensive or logistically difficult to obtain.
... The two groups differed significantly in their activity budget, with G3 resting more and G4 moving more. Differences in locomotor behaviour (such as moving) can reflect distinct habitat structures (Prates & Bicca-Marques, 2008) or distinct levels of scramble competition (Clutton-Brock et al., 1997;Clutton-Brock & Harvey, 1977;Isbell, 1991). We also witnessed more aggression in G3 than in G4 (unpublished data). ...
... proxies for food competition (Clutton-Brock & Harvey, 1977;Isbell, 1991), meaning that G4 is potentially facing greater food competition compared to G3. Greater food competition is commonly found in larger group sizes (Isbell, 1991). However, both groups were the same size, so the observed variation in DPL can derive not from intragroup competition, but from intergroup competition or habitat qualities and resourced availability. ...
The presence of other animals, both conspecifics and heterospecifics, is a major driving force for how animals organize themselves in space and time. Although theoretical models are available to explain the role of each in animal movement, fine-scale assessments of daily movement are scarce, particularly for primates. Hence, our goal was to assess whether and how the presence of conspecifics and heterospecifics influence spatiotemporal landscape use in two, wild, howler monkey (Alouatta guariba) groups. We followed the groups for 14 months in a large, continuous forest, during which we recorded their daily path length (DPL), home range, activity budget, feeding, and the presence of other groups (conspecifics) and other species (heterospecifics). The two groups differed in DPL, home range, proportion of fruits ingested, and time devoted to moving and resting. Partial least squares path modelling showed that variation in DPL was explained by the percentage of leaves or fruits ingested and by the presence of conspecifics, but not of heterospecifics. Group differences in several ecological variables emphasise the need to conduct further studies of space use with more groups in the same area to understand the underlying mechanisms of these differences. Moreover, our analysis shows that within-species interactions may be a stronger force in spatiotemporal organisation than interspecies interactions, at least in this folivorous primate. This is relevant from both a theoretical standpoint, and also when considering the consequences of habitat fragmentation and reduction. Deforestation leads to decreased resource availability and increased likelihood of encounters with conspecifics, which ultimately alters the proportion of food items ingested and increases the DPL, disrupting energy balance.
... Sex differences are common among primate species, in morphology, physiology, and/or behavior (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). There are two hypotheses that are usually proposed to explain dimorphism for body size and potentially, other dimorphisms: (1) males and females occupy different ecological niches and (2) sexual dimorphism is the result of sexual competition to access a mate according to evolutionary theories (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). ...
... Sex differences are common among primate species, in morphology, physiology, and/or behavior (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). There are two hypotheses that are usually proposed to explain dimorphism for body size and potentially, other dimorphisms: (1) males and females occupy different ecological niches and (2) sexual dimorphism is the result of sexual competition to access a mate according to evolutionary theories (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). In males, jealousy behavior is hypothesized to have evolved to prevent his mate from getting pregnant from an extra-pair copulation, and the male then spending energy to raise offspring that is not his own (Panksepp, 2010). ...
... Sex differences are common among primate species, in morphology, physiology, and/or behavior (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). There are two hypotheses that are usually proposed to explain dimorphism for body size and potentially, other dimorphisms: (1) males and females occupy different ecological niches and (2) sexual dimorphism is the result of sexual competition to access a mate according to evolutionary theories (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). ...
... Sex differences are common among primate species, in morphology, physiology, and/or behavior (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). There are two hypotheses that are usually proposed to explain dimorphism for body size and potentially, other dimorphisms: (1) males and females occupy different ecological niches and (2) sexual dimorphism is the result of sexual competition to access a mate according to evolutionary theories (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). In males, jealousy behavior is hypothesized to have evolved to prevent his mate from getting pregnant from an extra-pair copulation, and the male then spending energy to raise offspring that is not his own (Panksepp, 2010). ...
... Sex differences are common among primate species, in morphology, physiology, and/or behavior (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). There are two hypotheses that are usually proposed to explain dimorphism for body size and potentially, other dimorphisms: (1) males and females occupy different ecological niches and (2) sexual dimorphism is the result of sexual competition to access a mate according to evolutionary theories (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). ...
... Sex differences are common among primate species, in morphology, physiology, and/or behavior (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). There are two hypotheses that are usually proposed to explain dimorphism for body size and potentially, other dimorphisms: (1) males and females occupy different ecological niches and (2) sexual dimorphism is the result of sexual competition to access a mate according to evolutionary theories (Clutton-Brock and Harvey, 1997;Lukas and Clutton-Brock, 2013). In males, jealousy behavior is hypothesized to have evolved to prevent his mate from getting pregnant from an extra-pair copulation, and the male then spending energy to raise offspring that is not his own (Panksepp, 2010). ...
Jealousy is a social emotion that manifests as behavioral reactions from an individual toward a threat to a valuable relationship. Monogamous species exhibit jealousy-type behaviors as an adaptive response to preserve the relationship. Jealousy is also a complex, negatively-valenced emotion which may include fear of loss, anxiety, suspiciousness, and anger. Negative emotion may impair cognitive processes such as cognitive flexibility, an ability important for coping with new situations. However, little is known about how complex social emotions influence cognitive flexibility. To understand the interaction between jealousy and cognitive flexibility, we examined the neural, physiological, and behavioral factors involved in jealousy and cognitive flexibility in female titi monkeys. We presented subjects with a jealousy provoking scenario, followed by a reversal learning task and a PET scan with a glucose-analog radiotracer. We found that female titi monkeys reacted to a jealousy provoking scenario with increased locomotor behavior and higher glucose uptake in the cerebellum; however, hormone measures and were not affected. As only two females demonstrated cognitive flexibility, the effects of jealousy were difficult to interpret. Locomotion behavior was also negatively correlated with glucose uptake in brain areas linked with motivation, sociality, and cognitive flexibility. Surprisingly, glucose uptake in the orbitofrontal cortex (OFC) was significantly decreased during jealousy scenarios, while uptake in the anterior cingulate cortex (ACC) was decreased during reversal tasks. Our findings suggest that the presence of an intruder produces less visible behavioral reactions in female titis than in males, while still reducing activity in the OFC.
... Neither criterion is based on sufficient information to assign a species as dimorphic or monomorphic: body mass difference thresholds are both arbitrary and inconsistent, and a body mass ratio >1 can indicate either more frequent dimorphism or more extreme dimorphism in one sex than the other. In addition, research on SSD in mammals has tended to focus on a few taxa, namely artiodactyls, carnivores (especially pinnipeds), and primates (7,(19)(20)(21)(22)(23): clades with high rates of male-biased SSD (24). However, most mammals, by far, are rodents and bats (25), which are often under-represented in studies of SSD. ...
... Larger males were the norm for several of the less species-rich orders, while several others were evenly divided between larger males and monomorphism, and larger females were the norm for Lagomorpha (Figs. 2, S2). Notably, the orders that had the most prevalent male-biased dimorphism included Artiodactyla, Carnivora, and Primates: the orders that dominate the SSD literature for mammals (7,(19)(20)(21)(22)(23). Differences in rates of SSD at the family level were also evident, indicating that weighting our estimates based on species richness in each family was important. ...
Sexual size dimorphism (SSD) has motivated a large body of research on mammalian mating strategies and sexual selection. Despite some contrary evidence, the narrative that larger males are the norm in mammals – upheld since Darwin’s Descent of Man – still dominates today, supported by meta-analyses that use crude measures of dimorphism and taxonomically-biased data. With newly-available datasets and primary sources reporting sex-segregated means and variances in adult body mass, we estimated statistically-determined rates of SSD in mammals, sampling taxa by their species richness at the family level. Our analyses of >400 species indicate that although males tend to be larger than females when dimorphism occurs, males are not larger in most mammals, and suggest a need to revisit other assumptions in sexual selection research.
One-Sentence Summary
Taxonomically-balanced estimates of rates of sexual size dimorphism in mammals refute the ‘larger males’ narrative.
... For instance, arboreal species reliant on seasonal resources 318 may be more inclined to expand their dietary niche to include ground-based resources during 319 periods of food scarcity (33). Furthermore, fully or semi-terrestrial primates tend to be larger 320 than strictly arboreal primates and tend to live in larger groups (22,58,59). Both characteristics 321 are likely adaptations to high predation pressure and resource availability (59-63) and may have 322 facilitated the shift to terrestriality. ...
... Given that primates are known to perform certain activities more often at particular times of day (Clutton-Brock & Harvey, 1977), we averaged our behavioral data for each hour before calculating mean monthly and seasonal activity budgets to correct for biases in uneven sampling across the day (Bronikowski & Altmann, 1996;Hill et al., 2003;Xiang et al., 2010). We then converted activity proportions to observation hours/day to control for the effect of daylength on activity patterns (Lawes & Piper, 1992;van Doorn et al., 2010). ...
Black-and-white snub-nosed monkeys (Rhinopithecus bieti) rely on behavioral and dietary flexibility to survive in temperate latitudes at high-elevation habitats characterized by climate and resource seasonality. However, little is known about how elevation influences their behavioral and dietary flexibility at monthly or seasonal scales. We studied an isolated R. bieti population at Mt. Lasha in the Yunling Provincial Nature Reserve, assess the impacts of elevation on feeding behavior and diet. Across our sample, R. bieti occupied elevations between 3031 and 3637 m above mean sea level (amsl), with a 315.1 m amsl range across months and a 247.3 m amsl range across seasons. Contrary to expectations, individuals spent less time feeding when ranging across higher elevations. Lichen consumption correlated with elevation use across months and seasons, with individuals spending more time feeding on this important resource at higher elevations. Leaf consumption only correlated with elevation use during the spring. Our results suggest that R. bieti do not maximize their food intake at higher elevations and that monthly and seasonal changes in lichen and leaf consumption Am. J. Primatol. 2024;e23627. wileyonlinelibrary.com/journal/ajp |
... For instance, the "social brain hypothesis" (Dunbar 1998) states that the brain or specific brain regions have enlarged due to selective social pressures linked to factors such as group size (Dunbar 1992;Dunbar 1993;Barton 1996;Kudo and Dunbar 2001;Beauchamp and Fernández-Juricic 2004;Shultz and Dunbar 2006;Street et al. 2017), mating systems (Pawłowski et al. 1998;Iwaniuk 2001;Barton 2006), and social bonds (Dunbar and Shultz 2007;Emery et al. 2007). On the other hand, the "ecological intelligence hypothesis" suggests that environmental conditions, like foraging ecology, are the best correlates of brain morphology and cognitive abilities (Clutton-Brock and Harvey 1977;Iwaniuk and Nelson 2001;Hutcheon et al. 2002;DeCasien et al. 2017;Rosati 2017). There is an ongoing debate on the relative importance of these hypotheses (Powell et al. 2017;González-Forero and Gardner 2018), primarily due to the varying and conflicting research outcomes when testing various clades and taxa with varying biology and ecology (DeCasien and Higham 2019; Kappeler 2019). ...
Some cognitive abilities are suggested to be the result of a complex social life, allowing individuals to achieve higher fitness through advanced strategies. However, most evidence is correlative. Here, we provide an experimental investigation of how group size and composition affect brain and cognitive development in the guppy (Poecilia reticulata). For six months, we reared sexually mature females in one of three social treatments: a small conspecific group of three guppies, a large heterospecific group of three guppies and three splash tetras (Copella arnoldi)-a species that co-occurs with the guppy in the wild, and a large conspecific group of six guppies. We then tested the guppies' performance in self-control (inhibitory control), operant conditioning (associative learning) and cognitive flexibility (reversal learning) tasks. Using X-ray imaging, we measured their brain size and major brain regions. Larger groups of six individuals, both conspecific and heterospecific groups, showed better cognitive flexibility than smaller groups, but no difference in self-control and operant conditioning tests. Interestingly, while social manipulation had no significant effect on brain morphology, relatively larger telencephalons were associated with better cognitive flexibility. This suggests alternative mechanisms beyond brain region size enabled greater cognitive flexibility in individuals from larger groups. Although there is no clear evidence for the impact on brain morphology, our research shows that living in larger social groups can enhance cognitive flexibility. This indicates that the social environment plays a role in the cognitive development of guppies.
... Regarding non-sexual social selection, a priori, if population size and resources are constant, no effects should prevail from increasing group size. Now, socioecological models have long predicted and tested that because groups move together, even if resources stay the same, bigger groups must navigate more extensive areas (Clutton-Brock and Harvey 1977). If relationships are egalitarian, bigger groups should lead to fewer resources per capita, increasing the selection strength on performance for translating resources into reproductive success in all individuals, but most strongly on the sex with higher parental investment. ...
... We used (generalized) linear mixed models to analyse how phenotypic traits (size, short-term movement, reproductive success and effective dispersal) varied between connectivity treatment × location combinations (five levels). We used random effects (random intercepts) of genetic strain, experimental landscape nested in strain, and source location (stock, edge or core patch) nested in landscape to account for phylogenetic relatedness/ shared ancestry among populations (Clutton-Brock & Harvey, 1977;Hadfield & Nakagawa, 2010). ...
... There are several potential factors affecting group size (Clutton-Brock & Harvey, 1977). One possibility is that the distribution of resources, such as tree gum at Kwakuchinja, might encourage grouping. ...
Complex sociality in primates often is argued to have evolved after the appearance of diurnal activity. Studying the behaviour of nocturnal primates is fundamental to understanding the evolutionary origins of primate behaviour and ecology, yet much less is known about the nature of sociality in nocturnal primate species than their diurnal counterparts. We investigated group size, communication, and social interactions in free-ranging, Northern lesser galagos (Galago senegalensis) and present an activity budget and assessment of temporal variation in their behaviour. We collected continuous behavioural data using focal follows at three different stages of the night from individuals at Kwakuchinja, Northern Tanzania. We also collected group size data from Northern lesser galagos at Fongoli, Southeastern Senegal, and Lolldaiga Hills Ranch, Central Kenya. We categorised behaviours and, where sample sizes permitted, used Kruskal–Wallis tests to compare the durations of observed behaviours between the morning (pre-dawn), evening (from dusk), and later in the night. We analysed 140 focal follows (31.4 h of continuous behavioural data) and found that the proportion of time spent foraging, inactive, in locomotion, in self-maintenance, and vigilant, varied across the three stages of the night; galagos spent a great deal of their time inactive in the morning and foraging was more prevalent in the evening. Group size at Kwakuchinja was significantly larger than at Fongoli or LHR. Galagos were in groups of two or more in the majority of encounters at Kwakuchinja (55%; N = 76), rather than alone, but spent most of their nighttime activity alone at Fongoli (79%; N = 185) and LHR (80%; N = 142). Overall vocalisation rates were higher in the morning than other times throughout the night, although contact calls were relatively more frequent in the evening than other times. We recorded both affiliative and agonistic social interactions, but these contributed almost nothing to the overall activity budget. Our preliminary investigation into the social structure of Northern lesser galagos suggests that there are population differences in sociality and that overall, they connect more through vocalisations than through direct social interactions, thereby avoiding some of the potential costs associated with group-living. This variation in social organization suggests that we have more to learn about the drivers of sociality in nocturnal primates and the nature of their social structure.
... Gelada monkeys' activity time budget can fluctuate hourly and daily in response to environmental variations, the most important of which are food availability and quality (Kifle et al., 2013). Moreover, variations in the timing of daily activity patterns are characteristics of primates (Clutton-Brock and Harvey, 1977). Indeed, the daily activity patterns of Gelada monkeys vary significantly among habitats and during the day (Abebe et al., 2022). ...
The present study investigated the activity, range, and habitat utilization patterns of the Endemic Gelada Monkey (Theropithecus gelada) in and around Jer Silase Monastery in North Shoa Zone, Ethiopia. The study was conducted from January 2021 to October 2021 by considering the dry and wet seasons and stratifying the study area into natural forest, cliff/rocky, and farmland habitats. An instantaneous scan sampling method was employed to collect behavioral data. The activity patterns of three selected focal groups of Gelada monkeys were studied. GPS points of their predominant behavioral activities were recorded daily every 15 minutes from 7:00 to 18:00 for 12 days every month. A total of 5,592 individual activity records were obtained from 2312 scan samplings taken over 120 study days. Feeding comprised 54.52% of the activity time, followed by moving at 20.67% and socialization at 11.95%. A multivariate analysis of variance (MANOVA) revealed that the time allocated to different activity types varied significantly over the year with the month (Roy's Largest Root = 2.7, F 4,22 = 13.2, p < 0.001, partial η2 = 0.653). The longest mean monthly travel distance was 2817.61 ± 582.57 m, recorded at the Cliff/rocky habitat during the wet season. Gelada monkeys' daily range length and home range size extended more in the dry season. These findings may be explained by reduced habitat quality associated with livestock grazing, agricultural expansion, and charcoal production. Therefore, appropriate conservation measures should be implemented to minimize such adverse effects and conserve the endemic Gelada Monkey.
... Squirrel monkeys have a relatively high cephalization index or large brain size relative to their body size (Jerison, 1973;Russell, 1979). Evolutionary ecological factors that might promote development of a large brain and possibly the ability to anticipate future needs in NHPs are living in an arboreal environment and foraging for fruits patchily distributed over a large range (Clutton-Brock & Harvey, 1977, 1980Milton, 1988). Among New World primates, squirrel monkeys meet these criteria (Thorington, 1968). ...
The Bischof–Kohler hypothesis holds that nonhuman animals cannot anticipate a future event and take appropriate action when that event involves satisfaction of a need not currently experienced. Tests of the Bischof–Kohler hypothesis were performed with squirrel monkeys (Saimiri sciureus) and rats (Rattus norvegicus). In experimental trials with both species, a nonthirsty animal had its water bottle removed and then chose between a smaller and larger quantity of food. Consumption of the food induced thirst. Choice of the smaller quantity led to the return of the water bottle sooner than choice of the larger quantity. Monkeys reversed their baseline preference for the larger quantity of food when the experimental contingencies were introduced, but rats continued to prefer the larger amount. Although the rat findings support the Bischof–Kohler hypothesis, the monkey findings challenge it.
... Animals adapt to shifts in environments in order to optimize the use of resources for survival and reproduction [28]. Te fundamental factors that infuence animal behavior and activity patterns [29][30][31] encompass spatial distribution, food resource quality and seasonality, dietary requirements [32,33], reproductive strategies [34], seasonal variations, weather conditions, human-induced pressures, additional mineral supplementation, and more. Just as with other mammalian species, male and female wild bufaloes exhibit dissimilar energetic needs, often associated with variations in body size, a phenomenon prevalent across most herbivorous species [35,36]. ...
Te Asiatic wild water bufalo (Bubalus arnee Kerr), an endangered species featured on the IUCN Red List, is distributed across Nepal, India, Sri Lanka, Myanmar, Bhutan, Cambodia, and Tailand. Tis investigation delves into the reproductive and certain social behaviors exhibited by Bubalus arnee across distinct habitats and herd types within Nepal's Koshi Tappu Wildlife Reserve (KTWR) and Chitwan National Park (CNP) during the premonsoon and postmonsoon spans of 2018. Te data were amassed through direct observations employing focal animal sampling, continuous sampling, and scan sampling methodologies. Eight primary behavioral activities were noted: chasing, courtship, grazing, mating, mowing, snifng, urination, and wallowing. We carefully structured the gathered data and input it into a Microsoft Excel spreadsheet to facilitate analysis. For a more comprehensive visualization of reproductive behavior, we utilized the ggplot2 package within R-studio, enabling the creation of informative graphical depictions. During the premonsoon phase, Bull A exhibited six reproductive behaviors in KTWR. Notably, snifng was the most frequently observed behavior, recorded six times (37.5%) daily, succeeded by fghting and urination with four (25%) and three (18.35%) daily observations, respectively. Chasing, mating, and courtship were each observed once (6.25%) daily. In contrast, during both seasons, Bulls B, M, and J were not observed partaking in mating activities. When analyzing the postmonsoon reproductive behavior of the observed B. arnee in KTWR and CNP, a notable distinction emerged. In KTWR, there were four more instances of snifng behavior compared to CNP. In addition, courtship behavior was slightly more frequent in KTWR, occurring three times, whereas it was observed only twice in CNP. Similarly, urination activity was recorded twice as often in KTWR as compared to CNP. As a suggestion for future research, exploring the specifc factors infuencing the observed variations in reproductive behaviors and habitat preferences of Bubalus arnee could provide valuable insights into the conservation and management of these endangered species.
... The influence of activity pattern on primate biology has been a major focus of research in evolutionary anthropology because of its perceived importance for understanding the clade's early evolutionary history and the origin of crown Anthropoidea (Allman, 1977;Cartmill, 1992;Ross, 1996Ross, , 2000Ross, 2001, 2004;Kirk and Kay, 2004;Ravosa and Savakova, 2004). Numerous studies have demonstrated correlations between activity pattern and aspects of the visual system across primates (Kay and Cartmill, 1977;Kay and Kirk, 2000;Ross, 2004;Kirk, 2006aKirk, , 2006bRoss and Kirk, 2007;Heesy, 2008Heesy, , 2009), but the ecological consequences of diurnality and nocturnality are likely to be pervasive (Charles-Dominique, 1975;Clutton-Brock and Harvey, 1977; van Schaik and Kappeler, 1996;Kronfeld-Schor and Dayan, 2003). ...
Activity pattern has played a prominent role in discussions of primate evolutionary history. Most primates are either diurnal or nocturnal, but a small number are active both diurnally and nocturnally. This pattern—cathemerality—also occurs at low frequency across mammals. Using a large sample of mammalian species, this study evaluates two macroevolutionary hypotheses proposed to explain why cathemerality is less common than diurnality and nocturnality: (1) that cathemeral lineages have higher extinction probabilities (differential diversification), and (2) that transitions out of cathemerality are more frequent, making it a less persistent state (differential state persistence). Rates of speciation, extinction, and transition between character states were estimated using hidden-rates models applied to a phylogenetic tree containing 3013 mammals classified by activity pattern. The models failed to detect consistent differences in diversification dynamics among activity patterns, but there is strong support for differential state persistence. Transition rates out of cathemerality tend to be much higher than transition rates out of nocturnality. Transition rates out of diurnality are similar to those for cathemerality in most clades, with two important exceptions: diurnality is unusually persistent in anthropoid primates and sciurid rodents. These two groups combine very low rates of transition out of diurnality with high speciation rates. This combination has no parallels among cathemeral lineages, explaining why diurnality has become more common than cathemerality in mammals. Similarly, the combination of rates found in anthropoids is sufficient to explain the low relative frequency of cathemerality in primates, making it unnecessary to appeal to high extinction probabilities in cathemeral lineages in this clade. These findings support the hypothesis that the distribution of activity patterns across mammals has been influenced primarily by differential state persistence, whereas the effect of differential diversification appears to have been more idiosyncratic.
... Among primates, behaviors such as home range size and daily path length (DPL) fluctuate significantly between species, even within congeners living in diverse habitats (Milton & May 1976;Clutton-Brock & Harvey 2009). The DPL, generally presented as the average or mean length that an individual or group travels during a day, is affected by physical and ecological elements like the season, food availability, the variety of plants eaten, intergroup interactions, and level of terrestriality (Santhosh et al. 2015). ...
Rhesus macaques (Macaca mulatta, Mammalia: Primates: Haplorhini: Cercopithecidae) show a great deal of adaptability in different types of habitats. Understanding how these animals allocate their time with regard to their daily activities and ranging behavior is helpful to the design of effective conservation plans by allowing us to better understand their ecological necessities and behavioral responses to environmental changes. This study examined seasonal variation in the activity budget and ranging behavior of a semi-provisioned group of rhesus macaques inhabiting the Daunne Devi Temple area in the Daunne Forest, a subtropical forest in mid-hill of central Nepal. Behavioral data were collected on the adult members of the group using focal animal sampling from 27 October 2021 to 10 May 2022 (for a total of 29 days /227 hours of observation) during three time periods of the day: morning, 7.00–11.00 am; afternoon, 11.00–2.00 pm; and late afternoon, 2.00–6.00 pm. Simultaneously, ranging behavior was recorded by instantaneous scan sampling at 10-minute intervals with the aid of a GPS receiver. The adults in the study group spent the majority of the time resting (33.83%), followed by moving (26.67%), feeding (22.92%), and grooming (15.42%). Males spent significantly more time resting and moving, whereas females spent significantly more time in feeding and grooming. The time invested by the rhesus macaques in different activities showed seasonal variation, but lacked statistical significance. Daily path length ranged between 540.1–2905.4 m (mean = 1590 ± 576.96 m) with a statistically significant seasonal difference that might be attributed to the number of temple visitors and availability of provisioned food. Although the sample size was small and study duration was short, this is one of only a few studies providing empirical evidence suggesting the seasonal variation in activity budget and daily path length of semi-provisioned rhesus macaques.
... The activity time budget of geladas uctuates on an hourly and daily basis in response to environmental variables, the most important of which are food availability and quality [36]. Moreover, variations in the timing of daily activity patterns are characteristics of primates [37]. Due to that the daily activity pattern of geladas was signi cantly different in different habitats of the daytime [17]. ...
The study aimed to investigate the activity, ranging patterns, and habitat use of gelada monkeys. Understanding of behavioral ecology of primates in Jer Silase Monastery is crucial to their conservation and monitoring strategies. The study was carried out from January 2021 to October 2021 by considering both dry and wet seasons and by stratifying the study area as natural forest, cliff/rocky, and farmland. The instantaneous scan sampling method was employed to collect behavioral data. The activity pattern of three selected focal groups of geladas was studied, and predominant behavioral activities recorded GPS points every 15-minute intervals from beginning 7:00 h to dusk at 18:00 hr for 12 days per month. Mann-Whitney U test was employed to compare the seasonal variation of the behavioral activity patterns of geladas in the wet and dry seasons. A chi-square test (c ² ) of independence was also employed to examine the gelada monkeys’ behavior differently in different habitat types. Home range and day range length were determined by using Open Jump Toolbox (MOVEAN), and statistically tested by Mann–Whitney U test. A total of 5592 individual activity records were obtained during 2312 scan sampling on 120 study days. Feeding comprised 54.52% of the total scan, followed by moving 20.67% and socialization 11.95%. Habitat utilization of the gelada monkey in the three habitat types has a statistically significant difference (χ2 = 329.13, df = 2, p = 0.004). The result of multivariate analysis demonstrated that month has a statistically significant effect on an activity time budget Roy’s Largest Root = 2.7, F = 13.2, df = 4, p < 001, partial η2 = 0.653. The highest mean monthly travel distance of the focal group over the entire course of gelada recorded at the Cliff/rocky habitat was 2817.61 ± 582.57 m during the wet season. Geladas travel a longer daily range length and cover a wider home range size in the dry season. This shows the quality of the habitat is decreasing due to livestock grazing, agricultural expansion, and charcoal production. Therefore, to minimize such effects on gelada monkeys’ appropriate conservation measures should be implemented to conserve the gelada baboon.
... Juveniles may require more resources than adults due to requirements to grow and reach maturity [14][15][16]. Adults may exhibit periodic increases in resource requirements for reproduction [17,18], and this may further differ by sex [10,19] and body size [20][21][22]. Individuals within a population may also specialize to avoid competition, independent of their age, sex or size [23,24]. ...
A species may partition its realized ecological niche along bionomic and scenopoetic axes due to intraspecific competition for limited resources. How partitioning manifests depends on resource needs and availability by and for the partitioning groups. Here we demonstrate the utility of analysing short- and long-term stable carbon and nitrogen isotope ratios from imperiled marine megafauna to characterize realized niche partitioning in these species. We captured 113 loggerhead sea turtles (Caretta caretta) at a high-use area in the eastern Big Bend, Florida, between 2016 and 2022, comprising 53 subadults, 10 adult males and 50 adult females. We calculated trophic niche metrics using established and novel methods, and constructed Bayesian ellipses and hulls, to characterize loggerhead isotopic niches. These analyses indicated that loggerheads partition their realized ecological niche by lifestage, potentially along both bionomic (e.g. trophic) and/or scenopoetic (e.g. habitat, latitude or longitude) axes, and display different characteristics of resource use within their niches. Analysis of stable isotopes from tissues with different turnover rates enabled this first characterization of intraspecific niche partitioning between and within neritic lifestages in loggerhead turtles, which has direct implications for ongoing research and conservation efforts for this and other imperiled marine species.
... Other classifications exist (cf. Shuster & Wade 2003, Clutton-Brock 2016, but the one employed here is widely accepted and appears wellsuited to mountain ungulates. ...
1. Mountain ungulates of the subfamily Caprinae, including wild sheep, goats and goat-antelopes, show remarkable interspecific diversity in habitat preferences, social organisation and morphological features. We review how this diversity relates to their mating behaviour.
2. After introducing the ecology of mating systems and the evolution of the Caprinae, we investigate the pairwise, sequential relationships between habitat preferences, social behaviour, level of polygyny, and morphological features, and discuss the ecological processes underlying the patterns of mate monopolisation and acquisition.
3. From forest-dwelling, solitary, monogamous and monomorphic goat-antelopes, to highly dimorphic, polygynous and social wild sheep and goats inhabiting open landscapes, mountain ungulates reveal a close relationship between habitat openness and sexual dimorphism, through the level of sociality and that of mate monopolisation.
4. Although over the last few decades some information has been collected on the biology of Caprinae, our understanding of determinants of their mating systems is still hampered by limited data to estimate opportunities for sexual selection, as well as uncertainties over the occurrence and maintenance of alternative reproductive tactics, and lack of information on female mate choice.
5. The study of mating systems and that of the factors influencing them play a key role from an evolutionary and conservation standpoint. This is relevant to the Caprinae, whose main habitat is expected to be strongly affected by the ongoing climatic change, with potential effects on the phenology of their mating systems, and whose economic value is relevant for consumptive and nonconsumptive uses. A better understanding of the diversity and ecology of mating systems will require a wealth of additional field observations on male and female behaviour, as well as genetic assessments of reproductive success.
... The authors propose that allometric divergence in Bergmann clines was due to sexually antagonistic natural and/or sexual selection associated with environmental variation (i.e., temperature, food availability). Both human and non-human primates may exhibit patterns of sexual dimorphism consistent with Rensch's rule [33,34] but see [35]. In addition, although some evidence indicates that human mating systems are causally related to temperature and food availability Alexander et al., (1979) [36] this idea also remains controversial [37,38]. ...
Bergmann's and Allen's rules predict changes in body size and appendage length across temperature gradients for species with broad geographic distributions. Larger bodies and longer limbs facilitate cooling whereas smaller bodies and compact limbs limit heat loss. Although these patterns are highly repeatable (hence "rules" of ecology) the patterns and underlying mechanisms are less-well understood in humans. Here I show that variation in running performance among human male triathletes is consistent with both Bergmann's and Allen's rules. Males (but not females) with relatively larger body size and longer limbs performed better at hot compared to cold race venues and vice-versa. Consistent with results in other taxa, sex-specificity may reflect selection for sexual dimorphism. Results suggest that ecological patterns detected over large-spatial scales may arise from fine-scale variation in locomotor performance.
... All comparisons between the means of adult females and flanged males were significantly different. Evolutionary explanations for sex differences in the skeleton have been historically centered around malemale competition (Darwin 1871;Trivers 1972;Clutton-Brock and Harvey 1977;Leutenegger and Kelly 1977), including for orangutan male body sizes (Leutenegger and Kelly 1977;Mitani 1985;Rodman and Mitani 1987;Masterson and Leutenegger 1992;Uchida 1992;Leigh and Shea 1995). Among orangutans, flanged males are largest in size likely due to selection pressures related to intense competition for mates. ...
Among extant great apes, orangutans are considered the most sexually dimorphic in body size. However, the expression of sexual dimorphism in orangutans is more complex than simply males being larger than females. At sexual maturity, some male orangutans develop cheek pads (flanges) while other males remain unflanged even after becoming reproductively capable. Sometimes flange development is delayed in otherwise sexually mature males for a few years. In other cases, flange development is delayed for many years or decades, with some males even spending their entire lifespan as unflanged adults. Thus, unflanged males of various chronological ages can be mistakenly identified as ‘subadults’. Unflanged adult males are typically described as “female-sized”, but this may simply reflect the fact that unflanged male body size has only ever been measured in peri-pubescent individuals. In this study, we measured the skeletons of 111 wild adult orangutans (Pongo spp.) including 20 unflanged males, 45 flanged males, and 46 females, resulting in the largest skeletal sample of unflanged males yet studied. We assessed long bone lengths (as a proxy for stature) for all 111 individuals and recorded weights-at-death, femoral head diameters, bi-iliac breadths, and long bone cross-sectional areas (as proxies for mass) for 27 of these individuals, including seven flanged males, three adults confirmed-unflanged males, and three young adult likely-unflanged males. ANOVA and Kruskal-Wallis tests with Tukey and Dunn post-hoc pairwise comparisons, respectively, showed that body sizes for young adult unflanged males are similar to those of the adult females in the sample (all p ≥ 0.09 except bi-iliac breadth), whereas body sizes for adult unflanged males ranged between those of adult flanged males and adult females for several measurements (all p < 0.001). Thus, sexually mature male orangutans exhibit body sizes that range from the female end of the spectrum to the flanged male end of the spectrum. These results exemplify that the term ‘sexual dimorphism’ fails to capture the full range of variation in adult orangutan body size. By including adult unflanged males in analyses of body size and other aspects of morphology, not as aberrations but as an expected part of orangutan variation, we may begin to shift the way that we think about features typically considered dichotomous according to biological sex.
... Beginning with very early work in the 1970s by Forster (1973), Solow (1973), Stiglitz (1974), Brock (1977), and others, and culminating with more recent work investigating the Environmental Kuznets Curve by Stokey (1998), Aghion and Howitt (1998), and Jones and Manuelli (2000). All models of economic growth must provide changes in scale, composition, or procedures that satisfy the underlying assumptions of previous and later works of literature addressing the driving force behind economic growth. ...
Marine oil spills have been of tremendous concern due to their adverse impact on economic and ecological systems. Major oil spills triggered worldwide consciousness of marine spill response. In past decades, significant advances have been made in diverse aspects including prevention and preparedness, spill response and cleanup options, modelling of marine oil spills, and response decision support. Risk aversion was always a problem in the oil and gas business, but it has never been more serious. However, challenges remain particularly associated with cold and harsh environmental conditions. The research paper will explore how oil spills influence the environment and surrounding communities, as well as how this catastrophic issue causes the death of most marine species and threatens the sustainability of countries, with a focus on the Prestige and Northeast Brazil oil spills. The paper urges more organizations is needed to follow accessible standards to improve their operating performance and overcome technical uncertainty. Oil and gas companies collaborate with their peers to build transparent platforms that guarantee that automated production projects can be carried out at low cost and with relatively little interruption.
... Examining the linkages between ecological conditions and variation in primate social behavior has been a foundational aspect of primatology (Crook and Gartlan 1966;Clutton-Brock and Harvey 1977). This included the development of "socioecological models," with the goal of creating a unified framework to predict patterns of agonism, affiliation, kinship, and dispersal (e.g. ...
... For example, many ungulate herbivores rely on abundant, evenly distributed resources and live in large herds that increase protection against predators, whereas the majority of carnivores are solitary and have few social interactions outside of mating [2]. The effect of foraging and the distribution of food resources on social organization and structure has been particularly well-studied among primates [3][4][5][6][7][8], whose social systems vary tremendously, from graminivorous gelada monkeys living in herds of greater than 1000 individuals to solitary prosimians. According to classic socioecological models [7,9], the evolution of femalebonded groups (where females maintain affiliative bonds with other females and remain in their natal groups) can be explained by differences in the key resources constraining each sex; the distribution and defensibility of food resources serves as the primary determinant of female gregariousness and behaviour, and the distribution of females in turn structures the behaviour of males, thus linking food resources and central aspects of sociality such as group size, dispersal patterns and the formation of affiliative bonds. ...
Cooperation in food acquisition is a hallmark of the human species. Given that costs and benefits of cooperation vary among production regimes and work activities, the transition from hunting-and-gathering to agriculture is likely to have reshaped the structure of cooperative subsistence networks. Hunter–gatherers often forage in groups and are generally more interdependent and experience higher short-term food acquisition risk than horticulturalists, suggesting that cooperative labour should be more widespread and frequent for hunter–gatherers. Here we compare female cooperative labour networks of Batek hunter–gatherers of Peninsular Malaysia and Tsimane forager–horticulturalists of Bolivia. We find that Batek foraging results in high daily variation in labour partnerships, facilitating frequent cooperation in diffuse networks comprised of kin and non-kin. By contrast, Tsimane horticulture involves more restricted giving and receiving of labour, confined mostly to spouses and primary or distant kin. Tsimane women also interact with few individuals in the context of hunting/fishing activities and forage mainly with spouses and primary kin. These differences give rise to camp- or village-level networks that are more modular (have more substructure when partitioned) among Tsimane horticulturalists. Our findings suggest that subsistence activities shape the formation and extent of female social networks, particularly with respect to connections with other women and non-kin. We discuss the implications of restricted female labour networks in the context of gender relations, power dynamics and the adoption of farming in humans.
This article is part of the theme issue ‘Cooperation among women: evolutionary and cross-cultural perspectives’.
... In the case of sloths and other foregut-fermenting arboreal herbivores, their forestomach provides a site for fermentation and detoxification (Cork and Foley, 1991;Foley et al., 1995). The digestive capacity of herbivores is limited by their digestive tract, which is almost directly proportional to their body mass (Parra, 1978); therefore, herbivorous mammals tend to be larger and heavier than non-herbivorous mammals (Burness et al., 2001;Clutton-Brock and Harvey, 1977). However, arboreal animals do not have large body sizes owing to their ecology and the weight-bearing properties of trees (Cork and Foley, 1991;Eisenberg, 1978;Pauli et al., 2016). ...
Arboreal herbivores require large digestive tracts for leaf fermentation and detoxification; however, they must also have a low body mass that allows them to reach the foliage. The three-toed sloth, Bradypus tridactylus, experiences this trade-off, as leaves comprise 97.2% of its diet. Their calorie intake is extremely low owing to the low available caloric density of leaves and slow digestive processes related to leaf fibre fermentation and secondary compound detoxification. Sloths may require a high body temperature to assist fermentation; however, thermogenesis is energy-consuming. To investigate how sloths accomplish thermoregulation using marginal energy, we attached heart rate (HR) and temperature loggers to wild B. tridactylus individuals inhabiting the Amazon rainforest and recorded their HR and body surface temperature (Tskin). Tskin changed with ambient temperature (Ta) but was higher than Ta in 99.2% of cases. Increases in Tskin and HR did not coincide, suggesting that the increases were not caused by thermogenesis. Instead, they may passively increase Tskin by selecting warmer microhabitats and sunbathing. Consequently, 90.5% of Tskin were within 27.6–36.0 °C while the Ta fluctuated between 21.5 and 42.9 °C. This low-cost thermoregulation results in a low HR. In this study, the mean HR during observation was approximately 38.4% of the expected value based on the mammalian allometric relationship between body mass and HR. Thus, these properties may contribute to the low metabolic rates of sloths, alleviating their restricted energy intake.
Much historic work has focused on establishing geographical and ecological rules that broadly explain patterns in size variation. We examined geographic variation in Spotted Hyena skull size using geometric morphometrics and spatial statistics. We quantified size variation and sexual size dimorphism of the skull, and evaluated the influence of temperature, precipitation, land cover type, and population density on skull size. We found that female spotted hyenas are slightly larger on average than males. Our analysis of regional differences did not indicate geographic variation in sexual size dimorphism. Skull size of Spotted Hyenas varies with geography but does not adhere to Bergmann’s Rule. The smallest individuals of both sexes occur between −5.00° and 10.00° latitude and east of 28.50° longitude, with larger individuals being found elsewhere. Although Spotted Hyena skull size co-varies in some views with such variables as habitat type and climate indicators, skull size in this species most strongly co-varies with population density. The highest population densities are associated with the smallest skull size, possibly reflecting a relationship between high population density and access to resources. These results suggest that geographic variation in Spotted Hyena skull size is better explained by the energetic equivalence rule than Bergmann’s Rule.
Like other animals, primates tend to live in social groups where they communicate with one another and interact in both agonistic and affiliative ways. Primates are capable of forming various social bonds that can impact the individual’s health and well-being. Social behavior is flexible and dynamic, and the social organization of primates is complex. Primates of different species form various types of bonds with conspecifics. These relationships include pair bonds, friendships, coalitions, and other bonds among kin. Social relationships are a critical component of group life, where affiliative or aggressive interactions can have fitness consequences on the individual. In mammals, these different types of social relationships are regulated by different hormonal systems such as the oxytocin and vasopressin systems. The goal of this chapter is to provide a deeper understanding of different types of adult social relationships in primates by reviewing the variation in primate social behaviors and the neurobiology underlying it.
Decades of research have illuminated the consequences of early adverse rearing experiences in laboratory macaque populations. However, limited knowledge exists about the impact of traumatic episodes in non-laboratory environments. This study delves into the repercussions of illegal trade on socio-emotional and behavioural skills in five macaque species, all victims of poaching. We categorised their past experiences into seven aspects, encompassing maternal care and interactions with conspecifics. We assessed social engagement and cooperation by analysing social behaviours and employing the Social Responsiveness Scale. Emotional resilience was evaluated by measuring anxiety levels and the occurrence of abnormal behaviours, supported by a welfare questionnaire. Additionally, the introduction of Cattell’s 16PF questionnaire in macaques for the first time aimed to reveal the influence of traumatic experiences on their personality traits. Our findings emphasise the significance of early social exposure. The lack of juvenile social contact predicts reduced social behaviours and an inclination towards social avoidance in adulthood. Macaques raised by humans tend to exhibit more abnormal behaviours in social contexts, compromising their welfare. Deprivation of social exposure in infancy negatively impacts psychological stimulation and overall welfare. The duration of time spent in illegal trade correlates with heightened anxiety levels. Personality traits such as ‘Calmness’ and ‘Unfriendliness’ are influenced by rearing conditions, with macaques deprived of social interaction during their early years showing higher levels of introversion. In conclusion, the absence of social exposure during early life and hand-rearing due to illegal trade significantly shape macaques’ personality traits and their social and emotional skills.
The major aim of the present paper is an attempt at a general summarizing characteristics-of results obtained hitherto by sociobiology in the realm of studies upon social behaviour of man and animals. More specifically, the author deals with concepts of ethology, general questions of 'sociobiology, a problem of optimum strategy, basic questions of human sociobiology and meritoric and methodological status of the discipline. Formulation of the theory of evolution enabled scientific approach to animal behaviour. It had lead in the 1930-s to formation of ethology, a discipline investigating behaviour from the biological viewpoint. It gives much attention to animal social behaviour. In order to express interrelations between members of a group of individuals of the same species a notion of organization or social system is used in ethology. Usually social organization is looked upon as an -adaptation to a specific type of environment. Beginnings of sociobiology are related to formulation of the general theory of social behaviour by W. D. Hamilton. The central notion for this theory is a concept of inclusive fitness. It includes number of offspring of a given individual as well as the reproductive success of its relatives (a product of their offspring number and degree of kinship). A social behaviour is adaptive only when it increases inclusive fitness. This statement is the core of sociobiology understood as a systematic study upon biological basis for all types of human as well as animal behaviour. Its formulation dates back to the mid 1970-s and is contributed to E. O. Wilson. Present studies are concerned mainly with behaviour of insects, though recently a number of sociobiological analyses of mammalian and human bshaviour increases. In order to explain what is an optimum strategy of behaviour sociobiology makes use of a notion of stable strategy of individual behaviour in an evolutionary perspective. It includes mixed ratio of various individual behavioural strategies favourable in comparison with alternative behaviours maximizing general inclusive fitness of an individual. Major controversy is related to human sociobiology. Sociobiologists propose to include social sciences into evolutionary biology viewed as a basis for all the humanities. They use for their purposes a host of genetic, evolutionary and ecological data and aim to put in doubt a concept of distinctive place occupied by cultural evolution of man. Sociobiology is related to previous results of biological sciences, but differs considerably from traditional ethology. In sociobiology the basic unit of analysis is an individual together with a small group of its relatives, while in ethology the whole species is a primary object of considerations. The aim of sociobiology is not only to compare behaviour of various species (as in ethology) but also to attempt at elucidation of general laws concerning biology and evolution of social behaviour (including human behaviour). Ethology is concentrated upon studying neurological and physiological mechanisms of behaviour — deals with so-called direct bases of behaviour. To the contrary sociobiology attempis to find ultimate purposes of social-behaviour aimed at maximization of inclusive fitness. Despite a number of differences between the two disciplines one observes recently a process of merging basic notions and methods of investigation. Sociobiology nowadays constitutes a challenge for behaviouristic theories claiming on unlimited plasticity of behaviour and overlooking phylogenetic determinants of behaviour.
Social mating systems (e.g., monogamy, polygamy, or polyandry) are relatively stable behavioral strategies developed by environmental in animals, but the genetic imprint of a particular mating system is often incongruent with the social mating system due to extrapair matings. However, the genetics of mating systems remain little understood in rodents. In this study, we investigated the genetic signature of the mating system of 141 (63 females, 78 males) field-captured midday gerbils (Meriones meridianus)—a rodent species commonly found in the Minqin Desert in China—through microsatellite site analyses of genetic structure and relatedness. Seven pairs of highly polymorphic microsatellite loci were selected and were highly polymorphic, with the combined exclusion probability greater than 0.99. The parent pair paternity test by Cervus 3.0 software show that 11 mother–offspring and nine father–offspring relationships were identified in 2018, involving 26 individuals from 10 families. Similarly, 19 mother–offspring and 19 father–offspring relationships were identified in 2019, involving 48 individuals from 18 families. All three types of genetic mating structure were identified—monogamy (19 families), polyandry (4 families), and polygyny (5 families), providing evidence that the genetics underlying mating systems in this species are variable, can be incongruent with behavioral evidence for social mating systems, and could vary based on environmental cues, including degree of perceived or actual predation.
Conservation translocation is a common strategy to offset mounting rates of population declines through the transfer of captive‐ or wild‐origin organisms into areas where conspecific populations are imperilled or completely extirpated. Translocations that supplement existing populations are referred to as reinforcements and can be conducted using captive‐origin animals [ ex situ reinforcement (ESR)] or wild‐origin animals without any captive ancestry [ in situ reinforcement (ISR)]. These programs have been criticized for low success rates and husbandry practices that produce individuals with genetic and performance deficits, but the post‐release performance of captive‐origin or wild‐origin translocated groups has not been systematically reviewed to quantify success relative to wild‐resident control groups. To assess the disparity in post‐release performance of translocated organisms relative to wild‐resident conspecifics and examine the association of performance disparity with organismal and methodological factors across studies, we conducted a systematic review and meta‐analysis of 821 performance comparisons from 171 studies representing nine animal classes (101 species). We found that translocated organisms have 64% decreased odds of out‐performing their wild‐resident counterparts, supporting claims of systemic issues hampering conservation translocations. To help identify translocation practices that could maximize program success in the future, we further quantified the impact of broad organismal and methodological factors on the disparity between translocated and wild‐resident conspecific performance. Pre‐release animal enrichment significantly reduced performance disparities, whereas our results suggest no overall effects of taxonomic group, sex, captive generation time, or the type of fitness surrogate measured. This work is the most comprehensive systematic review to date of animal conservation translocations in which wild conspecifics were used as comparators, thereby facilitating an evaluation of the overall impact of this conservation strategy and identifying specific actions to increase success. Our review highlights the need for conservation managers to include both sympatric and allopatric wild‐reference groups to ensure the post‐release performance of translocated animals can be evaluated. Further, our analyses identify pre‐release animal enrichment as a particular strategy for improving the outcomes of animal conservation translocations, and demonstrate how meta‐analysis can be used to identify implementation choices that maximize translocated animal contributions to recipient population growth and viability.
Dusky and spinner dolphins are small-bodied odontocetes that show variation in socioecology across their range. New Zealand dusky dolphins and Hawaiian spinner dolphins of deep nearshore waters feed nocturnally upon prey species associated with the deep scattering layer, leaving the daytime free for rest and social interaction, often close to shore. In this chapter, we investigate relationships between foraging ecology, diel activity patterns, and sociosexual activities of dusky and spinner dolphins in breeding and nonbreeding contexts. We review similarities and differences between dusky and spinner dolphins related to mating strategies and tactics, socioecology, and evolution. We examine the effects of breeding season and variation in male testis mass and female receptivity on mating behavior. We further explore the influence of sociosexual behavior on female social grouping and calf rearing.
Wildlife grouping behavior is a significant survival strategy beneficial to all the group members. Migration to healthy food locations, defense from predators, mating, and social organization are some of the products of a well-established and organized grouping behavior of wildlife species such as elephants. Hence, the main objective of this study was to explore the grouping behavior of elephants on some ecological parameters in Mount Cameroon national park. Research data was collected within a period of four months by monitoring and observing elephant groups and their activities within their feeding ecology. Data collection was done during the first 15 days of each month and analyzed by Chi-square and correlation statistical models. In the study, elephant-group activity recorded a significance, X2 = 29.89 df = 8 p = 0.000, X2 = 12.95 df = 8 p < 0.05, and X2 = 11.801 df = 4 p = 0.019 on photo-period, atmospheric conditions, and habitat types respectively. The elephant groups also recorded a significant agreement, r = 0.061 p = 0.008, X2 = 17.35 df = 16 p < 0.05, and X2 = 27.62 df = 12 p = 0.006 on landscape, crop-farm, and crop-farm size estimate respectively. Additionally, elephant group activity recorded a significance, X2 = 18.39 df = 8 p = 0.018, r = 0.107 p < 0.05, X2 = 9.12 df = 8 p < 0.05, and X2 = 13.85 df = 8 p < 0.05 on farm destruction rate, farm destruction distance from human homes, elephant trails, and the crop-raided villages respectively. Group formation of elephants in the park is however reduced to smaller sizes probably due to the killing of elephants for human safety, a situation that could scare and cause some of the elephants to migrate to distant areas.
Mandrills (Mandrillus sphinx) have a unique social system for primates, with huge groups of hundreds of individuals and males moving in and out of the group seasonally. Despite intensive field studies conducted at several sites in the Congo Basin rainforests, the mechanisms and adaptation of their social organization are still poorly understood. How do groups maintain their huge size while moving around in the forest with poor visibility? How do solitary males find groups in the vast forests? And what are the adaptive advantages of these behaviors? In this review, I summarize what we know surrounding these questions and compare mandrill ecology with that of Neotropical social mammals, offering potential explanations for these questions. Group crowdedness and frequent exchange of long-distance calls could be keys to the collective movement of large groups that engage in regular subgrouping. The adaptive benefits of the large group size possibly lie in female tactics relating to infanticide avoidance and polyandrous mating. While very little is known about how solitary males find groups at the onset of the mating season, the adaptive function of their seasonal influxes can be relatively well explained as foraging and mating tactics. Since the major questions of mandrill social organization are strongly related to their movement ecology, intensive movement research using GPS telemetries and remote sensing is crucially needed to disentangle the social system of this intriguing monkey. Further, broader comparisons among the social movement of rainforest mammals will be essential to comprehensively understand their movement ecology.KeywordsGroup crowdednessGroup sizeLong-distance callMale influx
Mandrillus sphinx
Social organization
To find suitable food, organisms must navigate through a matrix of resources that vary in their concentrations of nutrients, toxins, and digestion inhibitors while also avoiding multiple hazards such as food competitors and predators. Wild primates eat a variety of foods that vary in their availability and quality both spatially and seasonally, and their movements differ accordingly. Here, we review the movement ecologies of primates in African forests with a focus on nutrient acquisition. We discuss how primates find different nutrients using a variety of sensory adaptations and adapt their movement to meet specific nutritional needs. We discuss future directions for research in this area.KeywordsNutritionMovementAfrican primatesEcologySensory ecologyPlant secondary metabolitesBrownian movement
Objectives:
To investigate whether the Cayo Santiago, Puerto Rico (Latitude: 18.1564°N; temperature range 19°C to 32°C) rhesus macaque population has acclimated to their tropical island conditions since arriving from Lucknow, India (Latitude: 26.8470°N; temperature range 8°C to 41°C) in 1938.
Materials and methods:
Using the derived skeletal collection, measurements were taken of long bone lengths, diaphyseal circumference, and body weight using 635 (237 males and 398 females) skeletally mature individuals. Measurements sampled colony members born over a 51-year time span at Cayo Santiago, from 1951 to 2002.
Results:
Results demonstrated that body weights and diaphyseal circumferences significantly declined in both males and females. Long bone lengths relative to body weight and diaphyseal circumference also increased in females. Whereas body weight, long bone length and diaphyseal circumference declined at near parallel rates in males.
Discussion:
The population has acclimated to homogenous, tropical, conditions of the Caribbean island since their arrival over 80 years ago. Trends in both sexes aligned with Bergmann's rule, though females displayed a greater decline in body weight, as well as greater affinity with Allen's rule, than did males. Buffering effects related to male competition may be responsible for this discrepancy. Overall, the Cayo Santiago populations, as shown over a significant period (1951-2002) of their history, have acclimated to their island conditions by decreasing in size and altering body proportions.
Social mating systems (e.g., monogamy, polygamy, or polyandry) are relatively stable behavioral strategies developed by environmental in animals, but the genetic imprint of a particular mating system is often incongruent with the social mating system due to extrapair matings. However, the genetics of mating systems remain little understood in rodents. In this study, we investigated the genetic signature of the mating system of 141 (63 females, 78 males) field-captured Midday Gerbils ( Meriones meridianus ) -a rodent species commonly found in the Minqin Desert in China-through microsatellite site analyses of genetic structure and relatedness. Seven pairs of highly polymorphic microsatellite loci were selected and were highly polymorphic, the combined exclusion probability was greater than 0.99. The parent pair paternity test by Cervus 3.0 software show that, eleven mother-offspring and nine father-offspring relationships were identified in 2018, involving 26 individuals from 10 families. Similarly, 19 mother-offspring and 19 father-offspring relationships were identified in 2019, involving 48 individuals from 18 families. All three types of genetic mating structure were identified: monogamy (19 families), polyandry (4 families), and polygyny (5 families), providing evidence that the genetics underlying mating systems in this species are variable, can be incongruent with behavioral evidence for social mating systems, and could vary based on environmental cues, including degree of perceived or actual predation.
Study on food preference of Rhesus monkey (Macaca mulatta) was conducted from September 2019 to September 2020 in the Margalla Hills National Park (MHNP) near Islamabad, which falls in Murree foothills between 450m--1500m elevation (N 330 44’25.5” E 0730 03’15.3”). The topography is rugged and
the climate is sub-tropical semi-arid. The flora of the park is mainly subtropical evergreen scrub forest on the lower slopes and subtropical pine forest at higher elevations. The data were collected by direct field observations on five selected groups: A, B, C, D and E of rhesus monkeys in various parts of the study area. The food remnants method was used in combination with fecal analysis and visual observation for food composition. Both macroscopic and microscopic fecal analysis were carried out using 150 fecal pellets, collected from study area. The microhistological fecal analysis showed the presence of 29 dietary plant species as compared to 30 plant species observed in the field. No animal derived food component was noticed in the diet. The results revealed that food composition consisted of 83% plant diet, 14% provisioned food items and 03% scavenging on garbage bins. To study food resource preference, the
monkeys were classified into five age/sex classes: Adult males, adult females, sub adults, juveniles and infants. Analysis of food resources preference of five age/ sex classes of rhesus monkeys revealed that it mainly varied due to nutritional requirements and physiological conditions of monkeys. Rhesus monkeys preferred succulent foods to the non-succulents. Eight different feeding categories: arboreal, ground, provisioning, scavenging, begging, stealing, snatching and suckling were defined. A total of 540
observations were taken for all age and sex classes. Arboreal and ground feeding were widely used by the monkeys while stealing and snatching were little used. There is a need to conduct research on feeding ecology, parasitology, food preference based on nutritional requirements of Rhesus monkey in MHNP.
Comparative analyses are the backbone of evolutionary analysis. However, their record in producing a consensus has not always been good. This is especially true of attempts to understand the factors responsible for the evolution of large brains, which have been embroiled in an increasingly polarised debate over the past three decades. We argue that most of these disputes arise from a number of conceptual errors and associated logical fallacies that are the result of a failure to adopt a biological systems-based approach to hypothesis-testing. We identify four principal classes of error: a failure to heed Tinbergen's Four Questions when testing biological hypotheses, misapplying Dobzhansky's Dictum when testing hypotheses of evolutionary adaptation, poorly chosen behavioural proxies for underlying hypotheses, and the use of inappropriate statistical methods. In the interests of progress, we urge a more careful and considered approach to comparative analyses, and the adoption of a broader, rather than a narrower, taxonomic perspective.
Have you wondered whether the striking differences in animal social groups have evolutionary consequences? We did and tried to find some answers and many questions. Although not known to us at the time of the start of this project, West-Eberhard constructed the logic for linking social systems and evolutionary speed back in the 80s. We have reviewed and discussed some of the evidence accumulated to date on the effects of animals' social lives on the speed of their evolutionary trajectories.
Conservation translocation is a common strategy to offset mounting rates of population declines through the transfer of captive-reared or relocated organisms to imperiled populations. However, these programs have been criticized for low success rates and husbandry practices that produce individuals with genetic and performance deficits. We assessed the disparity in post-release performance of translocated organisms relative to wild-resident conspecifics through a meta-analysis of 826 performance comparisons from 172 studies representing nine animal classes (101 species). We found that translocated organisms have 70% decreased odds of out-performing their wild-resident counterparts, supporting published claims of systemic issues hampering conservation translocation. Pre-release animal enrichment significantly reduced performance disparities, whereas our results suggest no overall effects of captive generation time or the type of fitness surrogate measured. Conservation managers should consider evaluations of post-release performance using sympatric (resident-control) and allopatric (true-control) wild-reference groups to ensure translocated animals contribute to recipient population growth and viability.
Gorillas are one of our closest living relatives, the largest of all living primates, and teeter on the brink of extinction. These fascinating animals are the focus of this in-depth and comprehensive examination of gorilla biology. Gorilla Biology combines recent research in morphology, genetics and behavioural ecology to reveal the complexity and diversity of gorilla populations. The first section focuses on morphological and molecular variation and underscores the importance of understanding diverse biological patterns at all levels in testing evolutionary and adaptive hypotheses and elucidating subspecies and species diversification. Following are discussions of the ecological constraints that influence gorilla social organization and highlight their surprising flexibility. The book ends with discussions of the conservation status of gorillas and the many and increasing threats to their continued survival. Giving insight into the evolutionary biology of these unique primates, this book will be essential reading for primatologists, anthropologists and evolutionary biologists.
A 20 months’ field-study of the Talapoin Miopithecus talapoin was carried out between 1966 and 1970 in North-East Gabon.
Twenty five troops were observed, all of them in inundated rain forest along rivers. Seventeen of these troops were located near human settlements. The communal night roost of each troop was invariably found near water. The sleeping sites were very stable throughout the year, though some seasonal changes may occur.
The troop size ranged from 59 to 80 individuals, and averaged 63 members. Troops living near human settlements were consistently larger.
Talapoins live in multimale groups where adult males act as leaders during troop movement and as «watch-dogs» at night. Within the group, females with their infants and year-old juveniles form definite subgroups, at least during the night. Among adults, females outnumber males.
Talapoins breed seasonaly in N.E. Gabon. The birth season of a given troop lasts for about 2 months during the period November-April. Most adult females give birth to one infant every year. The natality rate is therefore high, troops living near human settlements increasing by 11.7 to 25.7 % a year.
Talapoins are mainly frugivorous but also eat a number of insects. Their daily pattern of locomotor activity shows two definite peaks ; the one between early morning and 10.30 hours, the other between 13.30 and 18.30 hours.
The average distance travelled by a group during a day is 2,323 m (with a range from 1,500 to 2,950 m). During their daily wanderings, talapoins do not venture far from a river (never more than 450 m).
The home ranges of troops, established by mapping the daily movements of social groups at different times of the year, range from 1.0 to 1.4 km2. Home ranges include both the inundated forest where the night roosts are located, secondary growth forests and even plantations. The percentage utilization of the inundated forest is higher than expected from its size. About 70 % of the food consumed is found in this particular habitat. Variations in size and location of the Ntsi-Belong troop between 1966 and 1968 can be related to food abundance and availability. No territorial behaviour has been observed.
This is the first in a series of papers on some behavior patterns of New World monkeys. The main emphasis of these papers will be comparative. Special attention will be paid to social signal patterns (including hostile and sexual signals) and other patterns that differ significantly in the various species. It is hoped that analyses of these patterns may throw some light on the evolution of the group as a whole.
Results are presented of multivariate quantitative analyses of the relationships among 19 demographic, ecological, and social variables observed in 29 populations representing 21 primate species. The variables are group size, population density, day range, home range, percentages of adult males, adult females, and juveniles, body weights of adult males and females, sex ratio, arboreality, biomass, available food, frequencies of aggression, social grooming, play, and copulation. Analysis shows that three social behavior variables (frequencies of aggression, play, and copulation) are predicted significantly by using data on group size, density, day range, home range, and arboreality as predictors. Principal components analysis allows construction of a model that places the 29 populations in four clusters that compare closely with the adaptive grades of Crook and Gartlan (1966). The high incidence of infants in populations of large terrestrial primates probably results from slow maturation rather than from operation of r and K selection.
Preliminary survey of the large mammal fauna of the open Diptcrocarpous woodlands in Eastern Cambodja : Among the species observed by the author, two are included in the IUCN list of endangered Mammals, the Kouprey and the Douec langur. In the Phnom Prick Reserve 23 koupreys were censused in 1968. The Douc langur is still common ; contrary to what is the rule in other langurs, the Douc was always met in pairs during the dry season.
This is a preliminary report on the ecology and behavior of Lemur fulvus rufus (Fig. 1A, B). The brown lemur, Lemur fulvus, is almost exclusively an arboreal quadruped, and in general behavior and morphology resembles arboreal monkeys more than any other prosimian. Although subspecies of L. fulvus are among the most widely distributed and abundant of the Madagascar lemurs, there have been no published reports on long-term field studies of this species. Information for this study was collected during an 18-month field study (September 1969–January 1971) in the southwest of Madagascar. The focus of the study was to compare sympatric populations of L. f. rufus and Lemur catta, and a number of papers on that aspect of the research have been completed (Sussman, 1972, 1973, 1974).
The findings are presented from a 10-week field study on Saimiri oerstedi during mating season in southwestern Panama. The main study troop consisted of 23 monkeys. It used a home range of 0.175 km2 (43.5 ac) which was not a defended territory. Food was apparently scarce and the monkeys spent 95 % of each hour of their 14-hour day engaged in travel and foraging. Adult females, infants, juveniles and sub-adult males traveled as a cohesive, integrated unit. The troop’s 2 adult males usually traveled at the edge of the troop. A young adult male traveled further at the periphery of the troop. All overt social interactions were infrequent.
Aspects of the ecology of vervet monkeys (Ceropithecus aethiops) are described on the basis of a 21 month field study in East Africa. Analysis of home range utilization demonstrated differences between 4 groups. The smallest group distributed its time over a greater area than did the other groups. For 3 of the groups there appeared to be a strong relationship between group size and the amount of optimal habitat defended. The smallest group defended more optimal habitat than expected. However, this same group spent only 60% of its time in this habitat, whereas the other groups all spent more than 95% of their time in it. The smallest group may have avoided the optimal habitat of its territory as an area of frequent intergroup aggression, and as a result utilized a larger and less productive area. Sleeping-tree preferences of groups and individuals are described and discussed. The minimal distance traveled each day by vervet groups varied from 148 to 2,797 yd. In comparing the mean daily distance covered by 2 groups of equal size it was found that one moved significantly further than the other. More trips were made to permanent water holes between 1300 and 1500 hr and during the dry season than at other times. The frequency of group progressions was greatest at 0700 to 1000 and 1600 to 1900 hr. Study of food habits shows that they were opportunistic omnivores. Elephants were the greatest food competitors of the vervets. The monkeys had at least 16 potential predators. Outside of parks and reserves the greatest predator was the European commercial trapper. Ecological characteristics of vervets and their niche separation from baboons are discussed.
Polygamy in avian mating systems has generally been interpreted as a by-product of an unbalanced sex ratio, an assumption which is not necessarily true but which has apparently led to a stagnation of thought concerning evolution of polygamy in birds. Monogamy in populations with highly skewed sex ratios is known, and polygamy occurs in populations with even sex ratios. The Long-billed Marsh Wren falls into the latter group. Field studies in two separate populations of the marsh wren in Washington State revealed that bigamous associations were formed even when territorial bachelors were present in the vicinity, the bachelors being judged to occupy inferior territories. A female selecting a mate under these conditions might rear more young by pairing with a mated male on a superior territory than with a bachelor on an inferior one, notwithstanding the fact that she would obtain less help from her mate. A necessary correlate to this idea is a high density of mature males, such that some are forced to occupy the marginal sites. Monogamous populations of normally polygamous species (e.g., the marsh wrens of Sapelo Island, Georgia; European Wrens on various islands in the northern British Isles) may not occur in sufficient numbers during the breeding season to force some males into marginal habitats. An attempt is made to suggest some characteristics of males and their territories that are related to pair formation. There is evidence that the size of a male's territory and the total amount of emergent vegetation in it are correlated with his success in acquiring mates. Males' song rates tend to show an inverse correlation to pairing success, and males that failed to construct courting nests never paired. Whether features of territories or of males are important in pair formation, those factors leading to a high probability of pairing success must somehow be correlated with a high probability of breeding success.
Himalayan foothill rhesus monkeys were studied for a year at three forest habitats and in the town of Haldwani in Uttar Pradesh, India. Food supplies in the forest diminished both in abundance and variety as altitude increased during the ascent from tropical forests at the base of the foothills to subtropical pine and temperate oak forests at elevations of 5000 ft or more. Home range, day range, population density, and activity patterns also varied with altitude: monkey troops in the less favorable areas had larger home ranges and day ranges and were more often on the move during the day, while the lower elevations had a higher population density of monkeys. Increased mobility was a characteristic of one subtropical pine forest troop lacking any adult male. Both the abundance of food in Haldwani and the limited tolerance of the human inhabitants limited home ranges there to about 0.02 mi2, approximately 1/20 that of the smallest forest troop home range. Activity patterns were more stereotyped in the town than in the forest. The population density of the occupied portion of town was much more than in the forests, but less than on Cayo Santiago. Night time activity is probably greater in town.
Regardless of sex ratio, a polygynous mating is expected to be adaptive for the females as well as for the male. Two possible selective bases for the evolution of polygyny are considered: 1) One male may make it advantageous to several females to mate with him by appropriating a large share of a limited number of nest sites. 2) When a large share of the food for the young is obtained from the territory, local variations in food availability could influence the mating system. Given a sufficient minimum level of food supply, the difference in food availability between two males' territories may be great enough to permit a female to rear more young on the better territory, unaided by her mate, than she could on the poorer one even with full assistance from her mate. In this case, selection would favor a female pairing with the male on the better territory, even if this meant establishing a polygynous association. Fourteen of 291 species of North American passerine birds have been reported to be regularly polygynous or promiscuous. Thirteen of the 14 breed in marshes, prairies, or savannah-like habitats, where productivity resulting from solar energy is concentrated into a narrow vertical belt; that in a forest is spread unevenly over a broad vertical belt. Thus, the density of productivity--and of avian food sources--is potentially much greater in marshes and prairies than in forests. Hence, marshes and prairies are more likely than forests to present the minimum requisite food supply and sufficiently great differences in available food between territories for selection to favor polygyny.
Nighthawks, Chordeiles minor, lay their eggs on flat surfaces--in cities on flat roofs--roost in trees, and feed on flying insects which in turn presumably feed on vegetation. Thirteen neighboring nighthawk breeding home ranges in the center of Detroit, Michigan included on the average 10.4 ha total area, 97 small trees (including large shrubs), 70 large trees, and 38 flat roofs, representing 2.25 ha. More or less centrally in each home range and preferentially over flat roofs, whether being used for nesting or not, resident males performed diving and booming displays. High average and minimum distances between the centers of activity of the residents, together with observations of conflict between neighbors indicated that the home ranges were mostly defended and, since including feeding and breeding activities, constituted type A territories. Home range size which varied more than threefold, showed no significant correlation with the density of any environmental feature, including an index of photosynthesis, except for a negative correlation with number of flat roofs per ha. Six of the 13 home ranges bounded a 42 ha area unoccupied by nighthawks, which was, compared with the home ranges, deficient in trees and especially in flat roofs. These six home ranges tended to be larger than the remaining seven, though not to differ from them in density of trees and roofs, and in neither group was there correlation between size and density of these features. Thus, variation in home range size seems best explained by birds settling thickly where flat roofs are numerous, and through mutual aggressiveness having small home ranges, by birds not settling at all where flat roofs are scarce, and by home ranges next to such unoccupied areas expanding into them and/or at the expense of neighbors who must defend their entire boundaries. Although nighthawks do not always defend combined nesting and feeding areas, the apparently primary importance of aggressive interaction in determining home range size, in the present study, suggests that in nighthawks, as well as in other species having more strictly type A territories, aggressiveness at high population levels may reduce the proportion of individuals breeding and population natality rate below what resources would allow. A variety of evidence is reviewed on this point including the interspecific variation of home range size in relation to body mass which suggests that bird home ranges generally contain more food resources than required by the occupants.
T HE population fluctuations of many arctic predators, both avian and mam-malian, are associated with changes in the numbers of their major prey, the several species of arctic lemmings. Pitelka, Tomich, and Treichel (1955~) reported that the breeding densities of avian predators near Barrow, Alaska from 1951 to 1953 were correlated with lemming abundance. Th eir work confirmed that the Pomarine Jaeger (Stercorarius pomarinus) is a major lemming predator in northern Alaska and documented qualitatively the relationship of this species with the popula-tion cycle of the brown lemming (Lemmas trimucronatus) in that region. They also pointed out the desirability of quantifying the relationship between the two species. Accordingly the major objective of my study was an attempt to define the relationship between the populations of the Pomarine Jaeger and the brown lemming quantitatively, in order to determine the role of avian predators in the lemming cycle. In this paper I will discuss the food habits, nesting density, and reproductive success of the jaeger population and try to assess the impact of their predation on the brown lemming population. The interactions of populations in a simple system involving a single prey species and several avian predators should contribute to understanding of predator-prey relationships in general, in addition to the specific question of the role of predation as a possible cause of the lemming cycle itself.
(1) In this paper we describe a simulation model of feeding behaviour of birds in flocks. The model is built using a variety of hypotheses for which some evidence can be found in the literature. The model, which is primarily concerned with exploring the way in which flocking effects feeding success of individuals, contains three major behavioural components: (i) movements--both individual hopping movements and integrated flock flights; (ii) prey preference resulting from experience (to account for phenomena such as `searching image' formation); and (iii) social learning: the ability of one individual to learn the characteristics of a prey type by observing captures made by nearby individuals. (2) These have all been measured in the laboratory or field for one species or another of bird and we guessed at reasonable parameter values by looking at data in the literature. (3) Initially we tested the model by looking to see if we could produce a simulated flock that behaved in a fairly realistic fashion. The model flocks seemed to show movement patterns approximating to those of real flocks, which suggests that there are no major behavioural components about which we are unaware. We carried out a sensitivity analysis on the model to find out the effect of varying one input parameter at a time by a small amount, and measuring the effect of these variations on the rate of capture of a bird and the probability of a bird making no captures in 20 min. (= `risk'). (4) Both feeding rate and risk were sensitive to `giving up time' and capture rate was also sensitive to prey detectability. This means that our subsequent conclusions on the feeding efficiency of individuals in flocks of different sizes may only apply to the particular values of prey detectability and giving up time that we put into the model. (5) We used the model to carry out two `experiments'. In the first we measured the capture rate and feeding risk of birds which showed flocking behaviour and in birds which were not allowed to flock (the parameters involved in flocking were set to zero). The birds were allowed to forage for 20 simulated minutes in each experiment, and the experiments were carried out with various food distributions. The results showed that (a) there was no difference in the capture rate of flocking and non-flocking birds, (b) non-flocking birds had a significantly higher risk of doing badly, and (c) both capture rate and risk increased for flocking and non-flocking birds with clumping of the food. (7) In the second experiment we investigated the relationship between flock size, clumpedness of the food and feeding success. In this experiment flock size was fixed by putting birds into flocks of various sizes from one to sixteen. Again we measured both risk and capture rate. (8) The results showed that (a) risk decreases with increasing flock size for a wide range of degrees of food clumping (risk decreases appreciably up to flock sizes of about ten to twelve) and (b) on the whole small flocks (less than five) do best in terms of capture rate, but the `best' flock size in these terms varies with degree of clumping of the food and with the size of clumps. These results suggest that the `best' flock size in terms of risk is not the same as the best flock for maximizing feeding success. We suggest that for small birds, minimizing risk might be more important than maximizing success. (9) In conclusion, the model suggests the following points (a) that we can reasonably well describe the feeding and movement patterns of a flock on the basis of current knowledge, (b) that minimizing risk is an important consequence of flocking and (c) that several features of the degree of clumping of food influence feeding success.
Red deer on the Isle of Rhum (Inner Hebrides) show a well defined calving peak in late May and early June. Just before calving, hinds leave their usual social groups and move away from areas of high population density. Calves spend most of the day lying away from their mothers and are visited at intervals. During these visits, mothers show increased vigilance and flight distance from observers. When disturbed close to their lying calves, hinds are unwilling to approach the calf's position and may move the calf to a new area during the following 24 hours. Calves select their lying position with care, preferring to lie in long vegetation in places where they are sheltered from sight and can see the ground in front of them. All these behaviour patterns change during the first four weeks after parturition. The behaviour of hinds breeding for the first time differs little from that of experienced mothers.
A field study of the Lutong, (Presbytis cristatus) was conducted in Malaya. Lutong troops were observed for more than 1000 hours and were found to be markedly territorial. Only one control male lives in each troop and he actively defends the territory against incursions by other lutong males. Each troop moves slowly through its territory feeding and resting and comes into frequent visual contact with adjacent troops. Each troop is a well organized social unit but only the control males show consistent hostility to one another when troops meet. Grooming, play, sexual responses, maternal behavior and agonistic episodes are described as well as travel, feeding and diurnal patterns. These patterns appear similar to those reported in other Presbytis species, but contrast markedly with macaque and baboon reports. Differences in behavior between species of Presbytis do not exceed differences reported in the same species by different observers in different areas.
The nests of the Black‐headed Gull Larus ridibundus are closely aggregated into dense colonies and their use synchronized, these two phenomena together tending to produce a maximal clumping effect. Within such a colony however, nests were found to be spaced out to produce a non‐random uniform distribution. The commonest distance between neighbouring nests was found to be about one metre, in contrast to related species. This study was concerned with two aspects of this distribution pattern; its survival value and its behavioural causation.
It was found that pairs nesting just outside the colony had a much lower breeding success than those nesting in the colony and that nests on the colony fringe had a slightly lower success than those in the centre. Pairs laying during the peak laying period had a higher breeding success than pairs laying either earlier or later in the season. Since by far the most important mortality agent was predation, it seems likely that both clustering and synchronization of nesting function as antipredator systems and arguments in favour of this are discussed.
Variations in nest‐spacing within the colony were not correlated with variations in breeding success.
In the causation of the spacing between nests, territorial aggression was demonstrated to be an effective dispersion mechanism and the way in which this mechanism works was investigated in detail.
This spacing mechanism was not sufficient by itself to explain the observed densities, which were higher than one would expect from the aggression alone; there was also some tendency for birds establishing a new nest‐site to cluster close to others. The interaction between this, the territorial aggression of the residents and the subsequent avoidance responses of the settling birds, can explain the nest spacing pattern and probably also the observed densities.
In the current resurgence of interest in the biological basis of animal behavior and social organization, the ideas and questions pursued by Charles Darwin remain fresh and insightful. This is especially true of The Descent of Man and Selection in Relation to Sex, Darwin's second most important work. This edition is a facsimile reprint of the first printing of the first edition (1871), not previously available in paperback. The work is divided into two parts. Part One marshals behavioral and morphological evidence to argue that humans evolved from other animals. Darwin shoes that human mental and emotional capacities, far from making human beings unique, are evidence of an animal origin and evolutionary development. Part Two is an extended discussion of the differences between the sexes of many species and how they arose as a result of selection. Here Darwin lays the foundation for much contemporary research by arguing that many characteristics of animals have evolved not in response to the selective pressures exerted by their physical and biological environment, but rather to confer an advantage in sexual competition. These two themes are drawn together in two final chapters on the role of sexual selection in humans. In their Introduction, Professors Bonner and May discuss the place of The Descent in its own time and relation to current work in biology and other disciplines.