Social organization of Galagos in Kenyan coastal forests: II. Galago garnettii

The social organization of Galago garnettii was studied for the first time and the study included data from two different sites in the coastal forests of Kenya. A combination of mark-recapture and radio-tracking techniques was used to investigate patterns of inter- and intrasexual home range overlap. Patterns of range use were established by radio tracking focal individuals. Adult females of different ages shared highly overlapping ranges, while like-aged females showed little range overlap. Females matured and had their first infants in their natal ranges. Adult males' ranges were larger than those of females and overlapped them extensively. Resident adult males showed little range overlap with each other, unless they were of different ages. Turnover of males was frequent in both populations. Males probably dispersed from their natal ranges. Adults rarely slept together. The social organization of G. garnettii is relatively similar to that of the closely related G. crassicaudatus of southern Africa but contrasts with that of its sympatric congener, G. zanzibaricus. The differences and similarities between these three species are discussed in relation to diet and body size.     

The Round-Eared Sengi and the Evolution of Social Monogamy: Factors that Constrain Males to Live with a Single Female

Animal dispersion in space and time results from environmental pressures, and affects the outcome of a species' social organization. When females are solitary, males may either roam or be pair-living. We studied possible environmental influences affecting the social organization of the round-eared sengi ( Macroscelides proboscideus ) in a semi-desert in South Africa, using trapping and radio-tracking across 2.5 yr. Adult sex ratios did not deviate from 1:1 and we found no indication of sexual dimorphism in body mass. Females maintained exclusive areas, which had little overlap (<4%) with neighbouring females (NF), and males overlapped predominately only with the home range of single females. Generally, inter- and intra-sexual overlap with neighbouring individuals was low (3–6%) for both sexes, indicating territoriality and pair-living. Pairs were perennial and territories were maintained year-round. However, males generally maintained much larger areas than females, which were sensitive to population density. Male space use appeared to be primarily limited by the presence of neighbouring males. Female home ranges were smaller-sized despite changes in population density, possibly for energetic efficiency. Some paired males attempted to take over widowed females, but shifted back to their original home range following the intrusion of an un-paired male. We conclude that social monogamy is the predominant social organization in round-eared sengis in a semi-desert that may have resulted from females living solitarily in small exclusive territories, balanced sex ratios, and from a low variation of body mass between males.     

Social Organization of Lepilemur ruficaudatus

We characterize the spatial organization of red-tailed sportive lemurs (Lepilemur ruficaudatus) as a key aspect of their social organization and social system. Sportive lemurs are small (<1000 g), nocturnal and folivorous primates endemic to Madagascar. We studied a population of 57 individually-marked individuals in Kirindy Forest, western Madagascar, between 1995 and 2001. We radio-tracked 20 males and 26 females of the marked population to obtain detailed information on the size and location of their home ranges. Census data and morphometric measurements provided complementary data sets. Males and females occupied small (<1 ha) home-ranges. Long-term records from 9 individuals revealed home-range stability over several years. In 4 cases home ranges overlapped extensively with that of one member of the opposite sex; in 2 cases, a spatial association of 1 male and 2 females occurred. However, home ranges overlapped very little with neighboring individuals of both sexes. During the study period, spatially associated individuals used on average 5.6 sleeping trees within 117 days, but they spent on average only about every fourth night together. The data suggest that home ranges in red-tailed sportive lemurs are exclusively used by pairs or trios and that the modal social organization of red-tailed sportive lemurs is pair-living.     

Social organization of the Asian elephant (Elephas maximus) in southern India inferred from microsatellite DNA

Social organization of the Asian elephant (Elephas maximus) is not well understood in the absence of long-term studies of identified individuals. Adult Asian elephant females and their young offspring of both sexes form matriarchal groups, with pubertal males dispersing from natal groups, but whether these social groups represent families and whether males show locational or social dispersal were unknown. Using nuclear microsatellite loci amplified from dung-extracted DNA of free-ranging elephants in a large southern Indian population, we demonstrate that female-led herds comprise closely related individuals that are indeed families, and that males exhibit non-random locational dispersal.     

Genetic Structure and Kinship Patterns in a Population of Black Howler Monkeys, Alouatta pigra, at Palenque National Park, Mexico

We investigated the genetic structure and kinship patterns of black howler monkeys (Alouatta pigra) at Palenque National Park, Mexico. Fecal samples from 49 individuals residing in eight social groups were successfully genotyped for 19 polymorphic microsatellite markers known to be variable in other ateline primates. Overall, genetic diversity was low (H_o = 0.588) with an average of 4.2 alleles per loci (range = 2–8). We found that intergroup genetic variation among adults was relatively high (mean between‐group F_ST = 0.119), largely due to the genetic divergence of one study group from the others. Intragroup kinship patterns showed that in most social groups, either adult males, adult females, or individuals of both sexes resided with same‐sexed adult kin, suggesting that some black howler males and females may not disperse from their natal group or may disperse with related individuals. Of the six sampled immigrant males, two males joined established groups by themselves, and four males formed two pairs that each took over the social group they joined after evicting the resident males. Males in both these coalitions were genetically closely related, while the two solitary immigrants were not closely related to any of the resident males present in the group they joined. Am. J. Primatol. 74:948‐957, 2012. © 2012 Wiley Periodicals, Inc.     

Range use of the forest chimpanzees of Kibale: Implications for the understanding of chimpanzee social organization

We contrast the range use patterns of male and female chimpanzees (Pan troglodytes) based on repeated sightings over three years of 19 individuals in the Kanyawara community of Kibale Forest Reserve, Uganda. Depending on how home range size was calculated, male chimpanzees used an area that was 1.5 to 2 times greater than that of females. There was no difference between the sexes in whether their home ranges were used in a clumped or uniform fashion. However, males were more likely to be seen in boundary areas than females. These results are discussed in light of previously proposed models of chimpanzee social organization. It is concluded that the scenario in which females have smaller core areas within the defended home range of the males is most strongly supported by the range use patterns observed in Kibale chimpanzees. © 1993 Wiley-Liss, Inc.     

Influence of Reproductive Status: Home Range Size in Water Voles (Arvicola amphibius)

The relationship between home range and reproductive status of water voles (Arvicola amphibius) was studied by radio-tracking on an island off the coast of northern Norway in 2006–2009. The aim was to test assumptions about the species’ social structure relative to other microtines. Juveniles used fairly small ranges (about 400 m²), with no difference between males and females. Subadults, overwintered voles in April, had ranges similar to juveniles. Reproductively active males (mean 2774.0 m²) increased their range seven-fold relative to juvenile males, with ranges on average 3.3 times larger than adult females (mean 848.3 m²), which also expanded their range. Most litters were born in May and June, and as reproduction ceased in July adult males reduced their range whilst females did not. Body mass or year did not influence home range size. Overlap of home ranges varied, but could be extensive in both adult males and females. The water vole had a social structure similar to some Microtus species, but females appeared to be non-territorial and males perhaps conditioned territorial and non-territorial.     

Experimental evidence for density-dependence of home-range size in roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis> L.): a comparison of two long-term studies

The effect of experimental manipulation of population density on home-range size was investigated in two free-ranging roe deer (Capreolus capreolus) populations under contrasting environmental conditions. In these two long-term monitoring studies, one in Bogesund, Sweden (12 years) and one in Dourdan, France (10 years), deer density varied fourfold through varying culling pressure. Home-range data were collected by radio-tracking across the periods of contrasting density of the studies. We predicted that home-range size for females should vary in relation to the level of feeding competition, while for males, competition for mating opportunities should also influence range size, at least in summer when roe bucks are territorial. We found a highly consistent pattern over the two populations, with strong effects of deer density on home-range size, as well as significant differences between winter and summer ranges and between the sexes. Home ranges were consistently smaller at high density compared to low density. Males had larger ranges than females and this was particularly so during summer. Lastly, winter ranges were generally larger than summer ranges, particularly among females, although males at Dourdan had larger summer ranges compared to winter ranges. We suggest that the reduction of range size at high deer density during winter, as well as summer, is linked to the solitary behaviour and territorial social system of roe deer, with possible effects of dominance rank, even outside the mating season.     

Habitat selection and home range size of field voles<Emphasis Type="Italic">Microtus agrestis</Emphasis> in Słowiński National Park,Poland

Habitat preference, home range size and intra-specific overlap were investigated in summer 1998 among field volesMicrotus agrestis (Linnaeus, 1761) in Słowiński National Park (N Poland). Eight individuals (2 females, 6 males) were radio-tracked for one week in August. Field voles were shown to exhibit a marked preference for meadow and the ecotone between grassland and habitats with common reed, while avoiding alder forest and proper reedbeds. No significant differences between night and day in habitat-use of voles were noted. The results suggest that, at the end of the breeding season, it was food resources, rather than the risk of predation, played an important role in the voles’ utilisation of space. The home ranges of males were larger and more diverse than those of females; their sizes being correlated with body mass, such that heavier males had larger home ranges. This further suggests that intra-sexual competition exists between males for females. The low number of females influenced their spatial behaviour, as females had completely exclusive home ranges. Four males (out of six) had overlapping home ranges with other males; three of the overlaps were of less than 20%. Attributes of promiscuity (such as a 3.5:1 operational sex ratio of males to females, intra-sexual competition between males and the territorial exclusivity of females) influenced the social system. However, the period of radio-tracking during this study was too short to define accurately the social system in the field vole population.     

Demography,ranging patterns,and activity budgets of black spider monkeys (Ateles paniscus chamek) in the Manu National Park,Peru

Results of a long-term field study on the ecology and social organization of two groups of black spider monkeys (Ateles paniscus chamek) in Peru are reported. Demography, ranging patterns, and activity budgets provide insight into some of the proximate determinants of fission-fusion social organization in this species and illustrate the different strategies used by males and females to gain access to critical resources. Longitudinal data on known individuals provide evidence for male natal philopatry and female emigration at sexual maturity in this population. Interbirth intervals are long (mean = 34.5 months) in comparison with most other primate species, and 5 of 15 infants seen within a few days of birth died or disappeared before they were a year old. Home ranges are large (150–250 ha) and fairly discrete; overlap with neighboring groups is on the order of 10–15%. Males and females differed substantially in their ranging patterns; females, particularly those with infants, restricted much of their ranging to a “core area” 20–33% the size of the total group range, whereas males ranged more evenly over the entire area occupied by the group. Daily path length varied over almost an order of magnitude from 465 m to 4,070 m, with a mean of 1977 m. Males spent more time traveling and less time feeding than most females. These results are compared with those obtained in previous studies of Ateles and with similar data from other primate species to assess their implications for the evolution of fission-fusion sociality in spider monkeys. The ecological factors responsible for the evolution of very similar social organizations in spider monkeys and chimpanzees are discussed.     

Spider monkey home ranges: A comparison of radio telemetry and direct observation

The ranging patterns of two male and five female spider monkeys (Ateles geoffroyi) were studied with the use of radio telemetry in Santa Rosa National Park, Costa Rica. The average size of a spider monkey home range was 62.4 hectares; however, range size varied with sex, and, for females, with the presence of a dependent infant. The probability of encountering a radio-collared spider monkey in a three-hour search using radio telemetry (0.91) was much greater than using a visual search (0.20), and telemetric data resulted in a larger estimate of mean home range size than did observational data, when all subjects were compared. However, the difference appeared to be owing to the presence of male ranges in the telemetric, but not the observational, data. When the size of home ranges derived from radio-tracking data for adult females was compared to size of ranges for adult females derived from observations, the results were not significantly different. Adult males had larger home ranges than adult females, thus lending support to the hypothesis that males have adapted to the dispersion of females by occupying a large home range that overlaps the ranges of several adult females. The smallest home ranges were occupied by low-weight females with dependent infants, perhaps reflecting social and energetic constraints.     

Unraveling the dispersal patterns and the social drivers of natal emigration of a cooperative breeding mammal,the golden lion tamarin

The study of the social drivers of animal dispersal is key to understanding the evolution of social systems. Among the social drivers of natal emigration, the conspecific attraction, aggressive eviction, and reduced social integration hypotheses predict that sexually mature individuals who receive more aggressive behavior and are engaged in less affiliative interactions are more likely to disperse. Few reports have explored these proximate factors affecting emigration in cooperatively breeding species, particularly of Neotropical primates. In this study, we investigated the dispersal patterns and tested the social drivers of natal emigration in the golden lion tamarin (Leontopithecus rosalia) — an endangered species inhabiting Atlantic rainforests fragments in Brazil. We used behavioral and demographic data collected during 7 years from 68 groups of tamarins inhabiting 20 forest fragments. Our analyses from the 160 dispersing individuals showed that dispersal success is higher for males and for those engaged in parallel dispersal, but that males and females use different strategies to enhance their dispersal success, males immigrate into established groups while females form new groups. We did not find high levels of agonistic behavior among group members before natal emigration. Instead we found that conspecific attraction drives natal emigration in both sexes, while additionally the low level of affiliative interactions within the natal group triggers male emigration. We discuss natal emigration in the broader perspective of the cooperative breeding system and the implications of these findings for the conservation of the species.     

Interindividual interactions of Molina’s hog-nosed skunksConepatus chinga in the Pampas grassland of Argentina

During one year, we radiotracked two female and two male Molina’s hog-nosed skunksConepatus chinga (Molina, 1782), a little studied mephitid, in the Pampas of central Argentina, to analyze the static and dynamic interactions between individuals. Mean home range overlap was large (44.5%), but males shared a smaller proportion of their home ranges than females. The average percentage of localizations in the overlap area (39.3%) indicates that these areas were not marginal sections of individual home ranges, but this value was greater for individuals of different genders than intrasexual dyads. The Coefficient of Spatial Association confirmed that the distances between individuals of different sexes were smaller than between animals of the same sex. During simultaneous locations, females were closer than males, but reciprocal distances between individuals varied over the time. These patterns are congruent with those described as typical for mustelids and mephitids. Our results confirm that an analysis of home range overlap should not be considered complete without the study of dynamic interactions among individuals and their temporal variations, which are necessary to overcome the limitations of spatial overlap analysis.     

The ranging and nesting behaviour of Wood mice, Apodemus sylvaticus (Rodentia: Muridae), as revealed by radio-tracking

The social organization, nightly movements and nesting behaviour of Wood mice. Apodemus sylvaticus (L.), were studied by radio-tracking 35 individuals in a deciduous wood in north-east Scotland. The radios, which were mounted on collars and weighed 2·4 g, were only attached to mice weighing more than 20 g. During the breeding season (mid-March to December), when all the mice tracked were reproductively active, male ranges were on average 3·6 times as big (5110 m²) as those of females (1424 m²); male ranges overlapped considerably whilst females probably maintained ranges largely exclusive of one another. The ranges of males overlapped those of females apparently at random, each male's range encompassing parts of about five to ten females' ranges. Individuals' ranges changed position with time, although no total displacements were noted. No long-term bisexual associations were recorded. Nests appeared to be located at random within ranges, and nest sites were changed frequently. In summer, mice nested solitarily, whilst in winter they nested in groups of up to at least three. Typically, mice moved extensively over their ranges each night, males moving further between successive radio-fixes than females, and having fewer activity loci. Throughout the year, mice occasionally left their normal home ranges on excursions, sometimes over 100 m in length.     

Spatial and temporal interactions of free-ranging pacas (<Emphasis Type="Italic">Cuniculus paca</Emphasis>)

Although the paca is the most frequently hunted game species throughout the Neotropics, its behavioral and ecological requirements remain poorly understood. Here, we describe ranging behavior, spatio-temporal intraspecific interactions, and cavity use within a mosaic landscape in Central Belize, based on radio-tracking of four males and two females. This study is the first to investigate social interactions and spatial structure within a paca population in unprotected marginal habitat. We detected extensive home range overlap between males and between sexes. Male-male overlap was less extensive within core areas, while female core ranges were almost entirely occupied by one or more males. On average, pacas used at least six cavities within their home range. The majority of cavities were in the core areas and we did not detect simultaneous co-habitation of the same location. On average, females occupied cavities that were closer together, and closer to water bodies, than those of males. Overall, our study suggests a general tolerance during nocturnal foraging activities, but exclusive use of core areas and associated cavities. The larger ranges of males than females and the extensive overlap between conspecifics suggest a polygamous or promiscuous mating system in this landscape.     

Dispersal of Yearling Pronghorns in Western South Dakota

Abstract: We captured and radiocollared 57 pronghorn (Antilocapra americana) fawns in western South Dakota, USA, during May 2002–2003 and radiotracked them through 15 months of age, by which time all surviving individuals had established a permanent home range. We classified 56% (n = 19) of fawns as dispersers and 44% (n = 15) as residents. Eighty-four percent (n = 16) of dispersers departed natal home ranges in late October and occupied winter home ranges for 102–209 days before dispersing to permanent home ranges during April 2003 and 2004. Dispersal distances from natal ranges to permanent home ranges varied from 6.2–267.0 km. Winter home-range sizes for all individual pronghorns varied from 39.4–509.6 km. Permanent home-range size for all individuals varied from 15.5–166.1 km². Mean 95% permanent home-range size differed (P = 0.06) between residents (x̄ = 97.3 ± 15.1 km²) and dispersers (x̄ = 48.6 ± 16.0 km²), but was similar (P = 0.97) among sexes. Mean dispersal distance from natal to permanent home ranges was similar (P = 0.35) for males (x̄ = 54.2 ± 21.0 km) and females (x̄ = 26.3 ± 19.9 km). We suggest that habitat quality (i.e., patchiness) and pronghorn density, in part, stimulated dispersal. We hypothesize that as habitat patch size decreases, home range sizes and distance traveled during predispersal and dispersal movements by pronghorns will increase.     

Spatial genetic relationships in a population of the Japanese wood mouse Apodemus argenteus

Space-related relationships between individuals were investigated during the breeding season in a natural population of Apodemus argenteus (Temminck) by using the catch-mark-release method and microsatellite DNA markers. Several overlapping patterns of home ranges in breeding males and females were observed. Although this species is thought to be monogamous, DNA analysis revealed polygynous mating. In adults, relatedness between sexes was generally low and no apparent spatial genetic structure was observed. In juveniles, however, relatedness and geographical distance be-tween individuals were significantly negatively correlated. The relatedness between adult females decreased with distance, whereas there was not such a correlation in males. Long-distance movements were observed in current-year-born males. The differences in spatial genetic structure between adults and juveniles are thought to be produced by male-biased natal dispersal. An erratum to this article can be found at     

Age‐ and sex‐related differences in the spatial ecology of a dichromatic tropical python (Morelia viridis)

Abstract: Despite outnumbering their temperate counterparts, tropical snake species have been poorly studied. Yet, the few tropical species that have been studied show a variety of behavioural traits beyond those described in temperate species. Here we reveal both age and sexual differences in the movements of tropical green pythons (Morelia viridis: Pythonidae). We radio‐tracked 27 individuals (17 females and 10 males) for up to 18 months, locating individuals during both the day and night. The home range size for adult females (mean ± SE of 6.21 ± 1.85 ha) was correlated with snout–vent length. Neither adult males nor juveniles had a stable home range. Adult females had stable home ranges that overlapped considerably with those of other females and yellow individuals. Multiple radio‐tracked adult males passed through the territory of radio‐tracked adult females during the study. Females of all sizes were more likely to change position each day than males. There were no differences between the sexes or size categories in the distances moved in most months, although the variation in movement distances was higher in the dry season than during the wet season. In the wet season (January–March) movement distances increased and these were size‐ and sex‐related. This increased activity may be associated with mate searching. Males of M. viridis may maximize their rate of encountering mature females by roaming rather than maintaining a home range. Juvenile green pythons moved distances equal to adult snakes in most months despite their comparatively small size.     

Population ecology of the white-nosed coati (Nasua narica) on Barro Colorado Island, Panama

The white-nosed coati, Nasua narica , is a common Neotropical carnivore with a social structure of band-living adult females and solitary adult males. A coati population on Barro Colorado Island, Panama, was studied over a four-year period by mark-recapture, radiotelemetry. and direct observation of habituated individuals. The population density was approximately 51.5 individuals/km² and the sex ratio was 1:1. Band size varied from six to 26 individuals (mean = 15.3) with extensive fluctuation within and between years. Mean foraging group size was smaller (7.2 individuals) than population group size, and fluctuated with food availability, synchronous parturition, and the emigration of mature males. Mean home-range size of six bands was 0.33 km², and ranges of adjacent bands overlapped from 0–66%. One band fissioned during the study; however, the resulting bands did not disperse from the original home range. Seven adult males had a mean home-range size of 0.37 km², each extensively overlapping the home ranges of several other males. Observations of 10 adult males whose natal bands were known indicate that when males disperse they do not simultaneously leave the band's home range. Rather, their home ranges remain within or broadly overlapping those of their natal bands. This dispersal pattern is unusual within the order Carnivora.     

Dispersal Status Influences Hormones and Behavior in the Male Spotted Hyena

Male spotted hyenas (Crocuta crocuta) reach puberty at 24 months of age and then invariably emigrate from their natal clans 1 to 38 months later. Thus there are two classes of reproductively mature males in everyCrocutaclan: adult natal males born in the clan and adult immigrant males born elsewhere. In one free-living hyena population in Kenya, these two groups of males were compared with respect to measures of aggression, social dominance, sexual behavior, and circulating hormone levels. Adult natal males engaged in higher hourly rates of aggression than did immigrants, won all fights with immigrants, and were socially dominant to immigrants. In addition, adult natal males engaged in far lower hourly rates of sexual behavior with resident females than did immigrants, and natal males were never observed to copulate with natal females. Mean basal plasma cortisol values did not differ between the two groups of adult males, but cortisol concentrations in immigrants were positively correlated with tenure in the clan and with immigrant male social rank. Adult natal males had plasma testosterone levels significantly lower than those of immigrants. Social rank and plasma testosterone values were positively correlated among immigrant males. Thus two different relationships appear to exist between circulating testosterone and social rank in maleCrocuta:one apparent in immigrants and the other in natal adult males. Our results suggest that dispersal might disinhibit testosterone secretion in postpubertal male hyenas.