Social organization of Galagos in Kenyan coastal forests: I. Galago zanzibaricus

The social organization of Galago zanzibaricus 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. Associations in sleeping groups indicated social ties between individuals. Patterns of range use were established by radio-tracking focal individuals. Adult males generally had nonoverlapping ranges, shared with one or two females and their offspring with which the male regularly slept. Young females remained longer in their natal ranges than males and reproduced within their natal ranges. Range size and distance traveled per night were similar between the sexes; both sexes probably defended territories. None of the other galago (bushbaby) species studied to date show the degree of close male-female association found in G. zanzibaricus. This study thus extends the variety of social organization documented in nocturnal prosimians.     

Long-term Site Fidelity and Individual Home Range Shifts in <Emphasis Type="Italic">Lophocebus albigena</Emphasis>

We investigated long-term site fidelity of gray-cheeked mangabey (Lophocebus albigena) groups in Kibale National Park, Uganda. Concurrently, we monitored shifts in home range by individual females and subadult and adult males. We documented home range stability by calculating the area of overlap in successive years, and by recording the drift of each group’s monthly centroid from its initial location. Home ranges remained stable for 3 of our 4 groups (overlap over 10 yr >60%). Core areas were more labile, but group centroids drifted an average of only 530 m over the entire decade. Deviations from site fidelity were associated with dispersal or group fission. During natal dispersal, subadult males expanded their home ranges over many months, settling ≤4 home ranges away. Adult males, in contrast, typically dispersed within a few days to an adjacent group in an area of home range overlap. Adult males made solitary forays, but nearly always into areas used by their current group or by a group to which they had previously belonged. After secondary dispersal, they expanded their ranging in the company of their new group, apparently without prior solitary exploration of the new area. Some females also participated in home range shifts. Females shifted home ranges only within social groups, in association with temporary or permanent group splits. Our observations raise the possibility that male mangabeys use a finder-joiner mechanism when moving into new home ranges during secondary dispersal. Similarly, females might learn new resource locations from male immigrants before or during group fission.     

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.     

Dispersal, philopatry, and genetic relatedness in a social carnivore: comparing males and females

A balance must be maintained between the proportion of individuals dispersing and the proportion remaining philopatric such that inbreeding and resource competition are minimized. Yet the relative importance of dispersal and philopatric behaviour is uncertain, especially for species with complex social systems. We examine the influence of dispersal on genetic relationships of a white-nosed coati ( Nasua narica : Procyonidae) population from Panama. Field studies of the coati indicate a social system in which all females are highly philopatric and live in bands while all adult males become solitary at maturity, but do not disperse from the home range of their natal band. Based on analyses of multilocus DNA fingerprints, we confirm that female philopatry is the rule, long-distance dispersal is rare, and that relatedness between most bands is low. However, some new bands result from fission events and these bands retain relatively high relatedness to one another for several years. Adult males inhabiting the home range of a band are closely related to band members. In contrast, males and band members whose ranges do not overlap are unrelated or only slightly related. Adult males are also more closely related to other males whose home ranges they overlap extensively than to males whose home ranges they overlap only slightly. These results indicate that males initially disperse from their natal bands to reduce resource competition and not to avoid inbreeding. Inbreeding avoidance, if it occurs, results from more extensive range movements by males during the mating season.     

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 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.     

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.     

Woodland fragmentation affects space use of Eurasian red squirrels

When habitats become fragmented, variation in patch size and quality are expected to impose changes on the spacing pattern and social organization of animal populations. General theory predicts different possible responses including shrinking home ranges (fission response), increasing range overlap (fusion) and incorporation of multiple patches in the home range (expansion response) as fragmentation increases. We studied space use and social organization in a metapopulation of red squirrels (Sciurus vulgaris) in 15 woodland fragments differing in size and tree species composition. Home ranges and core areas of males were larger than females, and fragmentation had different and complex effects on the spacing pattern of both sexes. In food-supplemented patches, high densities led to increased intra-sexual overlap. In linear-shaped patches, squirrels used smaller home ranges and core areas and had lower male–male and male–female overlap levels, independent of patch quality or size. Home range and core area size of males increased with patch size, and male core areas overlapped extensively those of other males and females. Hence males seemed to show a fission response only in some patches. In contrast, home range and core area size of females was not related with patch size, but decreased with habitat quality, supporting predictions of a fusion response and intra-sexual defense of food-based core areas. Hence, where patch size and shape strongly affected space use of male red squirrels, social organization of females was only affected in small, food-supplemented patches, suggesting that the basic spatio-social organization of adult females is very resistant to fragmentation.     

Social and Spatial Segregation in Alpine Ibex (Capra ibex) in Bargy,French Alps

Outside the rut, a gradual social and spatial segregation was observed between the sexes as male Alpine ibex (Capra ibex) aged. In addition, males joined similar-age peer groups and segregated spatially as the age difference increased. The patterns varied seasonally, influenced by biological and ecological events. During the rut, males and females intermingled and used greatly overlapping ranges. Males ≥ 9 years first left female groups but social and spatial segregation were not complete until May. Younger males shifted to male groups more gradually. Females and males over 2 years of age used almost exclusive ranges in summer and early autumn. Social grouping and range overlap between ibex classes were correlated outside the rut. Grouping and spatial overlap between young and old males were negatively related to association with females.     

Social behavior in fission–fusion groups of red uakari monkeys (Cacajao calvus ucayalii)

Primates living in large groups that divide to forage must have social systems compatible with this mode of living. Uakari monkeys (Cacajao spp.) live in large groups and exhibit a form of fission–fusion grouping, but their social organization is poorly understood. We present some of the first data on social behavior for this genus based on a study on Cacajao calvus ucayalii. They traveled in multimale multifemale groups of highly variable sizes, with bachelor units on the periphery. Adult males were affiliative, and adult females associated with more than one adult male. Adult females typically traveled with their dependent offspring and an older juvenile within the group. In parties of two or more males, individuals engaged in previously unreported display behaviors and acted together to aggressively chase other males. Breeding was seasonal, and mating occurred away from other group members. We speculate on the social organization of C. calvus ucayalii, in which dispersal may be bisexual and peripheral males are affiliative with one another. Affiliated males appear to cooperate in fighting and displaying to other males for access to females during the breeding season. Am. J. Primatol. 71:976–987, 2009. © 2009 Wiley‐Liss, Inc.     

Female in space,or female in space and time? First data on the socio-spatial organization and mating system of the woodland dormouse (Graphiurus murinus)

We studied the socio-spatial organization of the woodland dormouse, Graphiurus murinus, by means of a monthly live-trapping and nest-box monitoring programme. Adult male (N = 5) home ranges were almost twice as large as those of females (N = 8), and both intra and intersexual home-range overlap was significantly larger in males than in females. However, the dispersion pattern of females was rather clumped, even during the breeding period, suggesting that females are not territorial. Sexual receptivity in females was asynchronous. In such circumstances, the Female in Space and Time hypothesis predicts that males will be non-territorial, a scenario which is matched by our data. Therefore, it is likely that the woodland dormouse has a promiscuous mating system.     

Spacing pattern in a social group of stray cats: effects on male reproductive success

Reproductive consequences of male spacing patterns have received relatively little attention in nonterritorial mammals, in particular in group-living species, where most studies have focused on the relation between social rank and reproductive success. We investigated the effects of spacing pattern on male reproductive success within a social, nonterritorial, promiscuous population of stray cats, Felis catus. Male home ranges overlapped home ranges of many females, consistent with a promiscuous mating system. Furthermore, males with the largest home ranges included the most female home ranges; they successfully reproduced with these females and had the highest reproductive success. Home range size predicted male reproductive success even when controlling for the effect of social rank. However, males also reproduced with females whose home range did not overlap their home range, suggesting that males can make quick excursions outside their home range to find new mating opportunities. We conclude that, in group-living situations, a male's ability to maintain a large home range may be one of the principal causes of variation in mating success in the stray cat.     

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.     

Exclusive core areas and intrasexual territoriality in Eurasian red squirrels (<Emphasis Type="Italic">Sciurus vulgaris</Emphasis>) revealed by incremental cluster polygon analysis

When animal home ranges overlap extensively in species lacking overt territorial behaviours, identifying exclusive core areas within individual ranges can be difficult. By analysing the size and overlap of successively smaller core areas among individual Eurasian red squirrels (Sciurus vulgaris), we determined exclusive areas within the home ranges of resident males and females. Possible effects of habitat composition and food supplies were explored by monitoring squirrels in different conifer forests and during years with low and high tree seed production. Using outlier-exclusive cores (OEC) revealed that the total ranges consisted of large sally zones (on average, 35% of the total minimum convex polygon [MCP] range) around home ranges with multi-nucleate cores. The mean OEC home range size did not differ between the sexes but was larger with poor food availability. Home ranges (99% incremental cluster polygons [ICP]) overlapped extensively between sexes (average overlap high food–low food: males by females 21–40%, females by males 43–45%) and among males (males by males 26–44%), while intrasexual overlap among females was low (9–10%). The overlap of inner cores among females rapidly approached zero, suggesting the intrasexual territoriality of 75% core areas. This was not the case among male squirrels, for which intrasexual overlap averaged only 4% at 50% but 18% at 75% core areas. Even the smallest inner cores had some degree of intersexual overlap, indicating that complete territoriality did not occur in this species. Female home ranges were more strongly affected by annual fluctuations in food supplies than male ranges. Females reduced the size of their food-based intrasexual territories when food availability increases. Males probably benefit from using larger home ranges and core areas, which overlap with the ranges of several females, by increasing their probability of successful mating.     

Isolation of females prior to parturition reduces neonatal mortality in Galago

Eighteen years of birth records for three species of Galago at the Duke University Primate Center were examined to determine the effects of isolation of pregnant females on neonatal mortality rates. Isolation significantly decreased neonatal mortality rates in all three species over neonatal mortality rates in infants born to unisolated females. The frequency of cannibalism of infants did not differ between isolated and unisolated females. Secondary sex ratio differed significantly from 1:1 for all three species, but higher mortality in males in the first 10 days of life resulted in sex ratios that did not differ from 1:1 in G. garnettii and G. crassicaudatus.     

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.     

Male and female range use in a group of white‐bellied spider monkeys (Ateles belzebuth) in Yasuní National Park,Ecuador

Spider monkeys (Ateles sp.) live in a flexible fission–fusion social system in which members of a social group are not in constant association, but instead form smaller subgroups of varying size and composition. Patterns of range use in spider monkeys have been described as sex‐segregated, with males and females often ranging separately, females utilizing core areas that encompass only a fraction of the entire community range, and males using much larger portions of the community range that overlap considerably with the core areas of females and other males. Males are also reported to use the boundary areas of community home ranges more often than females. Spider monkeys thus seem to parallel the “male‐bonded” patterns of ranging and association found among some groups of chimpanzees. Over several years of research on one group of spider monkeys (Ateles belzebuth) in Yasuní National Park, Ecuador, we characterized the ranging patterns of adult males and females and evaluated the extent to which they conform to previously reported patterns. In contrast to ranging patterns seen at several other spider monkey sites, the ranges of our study females overlapped considerably, with little evidence of exclusive use of particular areas by individual monkeys. Average male and female home range size was comparable, and males and females were similar in their use of boundary areas. These ranging patterns are similar to those of “bisexually bonded” groups of chimpanzees in West Africa. We suggest that the less sex‐segregated ranging patterns seen in this particular group of spider monkeys may be owing to a history of human disturbance in the area and to lower genetic relatedness between males, highlighting the potential for flexibility some aspects of the spider monkeys' fission–fusion social system. Am. J. Primatol. 72:129–141, 2010. © 2009 Wiley‐Liss, Inc.     

Home ranges of European mink<Emphasis Type="Italic">Mustela lutreola</Emphasis> in southwestern Europe

We radiotracked 7 European minkMustela lutreola Linnaeus, 1761 (5 males and 2 females), to determine their distribution, size and temporal changes of their home range in an area of southwestern Europe, where American minkM. vison was not established. Size of home ranges varied from 11 to 17 km along watercourses in males and were 0.6 and 3.6 km in females. Home ranges of males were larger than those found in previous studies. Most females captured (either radiotracked or not) were found within the home range of males. Males occupied adjoining river sections with minimal range overlap, suggesting an intrasexually exclusive spacing pattern for males. Each month males used new river stretches, mainly along tributaries; meanwhile they showed a steady use of their stem river section. Resting sites were mainly beneath dense brambles ofRubus patches located in the river bank.     

Social interactions and the life history of femalePan paniscus in Wamba,Zaire

The unit-group of Pan paniscustends to form one large mixed party consisting of most of its members. Females usually stay in the party irrespective of their estrous state. They aggregate in the center of the party; and, older females stay in the most central part. Adult and adolescent sons of the old adult females stay in the central part more than males without mothers in the unit-group do. Females leave their natal unit-groups as older juveniles or in early adolescence and. settle in another unit-group after visiting several. Newly immigrated young females are eager to have social interactions with senior females to improve their social positions. Females become less eager to interact socially with other females when they have their own offspring. The strong bond between mother and son continues into his adulthood; and, females in old age become important members of the unit-group, both as the targets of association for younger females and as the mothers of highranking males. High social status of females seems related to their cohesive grouping tendency. The consistency of the multimale/multifemale party and the existence of prominent mother-offspring subunits are unique characteristics of P. paniscusamong the Pongidae. This social structure may provide a feasible model of the basic society from which human society evolved.     

Spatial and temporal habitat use of kob antelopes (Kobus kob kob, Erxleben 1777) in the Comoé National Park, Ivory Coast as revealed by radio tracking

Spatial and temporal habitat use of kob antelopes (Kobus kob kob) have been investigated in the Comoé National Park (Ivory Coast, West Africa) by use of radio telemetry. A total of 23 kob were equipped with radio collars and radio tracked for up to 15 months. Home ranges of males were smaller and those of females larger than expected from theoretical models. Adult males used smaller areas than adult females and did not show seasonal home range shifts. Daily distances travelled did not differ between sexes. Kob walked less during the night than by day and covered shorter distances in the wet season. Whereas an increase in home range overlap between females resulted in higher rates of association among individuals, association of adults of mixed sexes was not correlated with the degree of home range overlap. Territorial behaviour of males and predator avoidance by females are suggested to explain the sex‐specific differences in home range size of adults and the deviation from the predicted sizes. Predator avoidance is presumed as the main reason for the reduced walking distances at night as well as in the wet season. Reproductive behaviour and feeding ecology are assumed to determine the degree of association of conspecifics.