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The Andean bear alopecia syndrome is a progressive and chronic condition documented in ex situ populations. Recent advances focus on treating symptoms, not preventing future cases. We therefore explored the epidemiology of this syndrome through an analysis of husbandry and veterinary conditions of 63 Andean bears (26M:37F) housed in North and South American zoos and other ex situ circumstances. We had the most complete information for the North American population and found that 29% of females (n = 24) were affected. No males (n = 26) were affected. An analysis of generalized linear models indicated that three models were competitive in describing the occurrence of the condition (i.e., ΔAICc ≤ 2): the model including only the individual's sex (χ2 = 13.41, df = 1, p

Close associations between adult males and lactating females and their dependent infants are not commonly described in non-monogamous mammals. However, such associations [sometimes called “friendships” (Smuts 1985)] are regularly observed in several primate species in which females mate with multiple males during the fertile period. The absence of mating exclusivity among “friends” suggests that males should invest little in infant care, raising questions about the adaptive significance of friendship bonds. Using data from genetic paternity analyses, patterns of behavior, and long-term demographic and reproductive records, we evaluated the extent to which friendships in four multi-male, multi-female yellow baboon (Papio cynocephalus) groups in Amboseli, Kenya represent joint parental care of offspring or male mating effort. We found evidence that mothers and infants benefited directly from friendships; friendships provided mother–infant dyads protection from harassment from other adult and immature females. In addition, nearly half of all male friends were the genetic fathers of offspring and had been observed mating with mothers during the days of most likely conception for those offspring. In contrast, nearly all friends who were not fathers were also not observed to consort with the mother during the days of most likely conception, suggesting that friendships between mothers and non-fathers did not result from paternity confusion. Finally, we found no evidence that prior friendship increased a male’s chances of mating with a female in future reproductive cycles. Our results suggest that, for many male–female pairs at Amboseli, friendships represented a form of biparental care of offspring. Males in the remaining friendship dyads may be trading protection of infants in exchange for some resources or services not yet identified. Our study is the first to find evidence that female primates gain social benefits from their early associations with adult males.

Group living provides benefits to individuals while imposing costs on them. In species that live in permanent social groups, group division provides the only opportunity for nondispersing individuals to change their group membership and improve their benefit to cost ratio. We examined group choice by 81 adult female savannah baboons (Papio cynocephalus) during four fission events. We measured how each female’s group choice was affected by several factors: the presence of her maternal kin, paternal kin, age peers, and close social partners, her average kinship to groupmates, and her potential for improved dominance rank. Maternal kin, paternal kin, and close social partners influenced group choice by some females, but the relative importance of these factors varied across fissions. Age peers other than paternal kin had no effect on group choice, and average kinship to all groupmates had the same effect on group choice as did maternal kin alone. Most females were subordinate to fewer females after fissions than before, but status improvement did not drive female group choice; females often preferred to remain with social superiors who were their close maternal kin, rather than improving their own social ranks. We suggest that during permanent group fissions, female baboons prefer to remain with close maternal kin if those are abundant enough to influence their fitness; if they have too few close maternal kin then females prefer to remain with close paternal kin, and social bonds with nonkin might also become influential.

Female spotted hyenas (Crocuta crocuta) are larger and more aggressive than males, and their genitalia are heavily 'masculinized'. These odd traits in females pose unusual challenges for males during courtship and copulation. Here our goals were to describe and quantify the behavior patterns involved in courtship and copulation in Crocuta, and determine whether rates of affiliative behavior directed toward females by males vary with female age, social rank, or time to conception. We also inquired whether consort formation with a particular female was necessary for a male to sire that female's cubs. Behavioral observations and paternity data based on 12 microsatellite loci were collected over 11 years from free-ranging hyenas in Kenya. Several of the courtship displays exhibited by male hyenas differed from those found in other carnivores, and appeared to reflect intense motivational conflict between tendencies to approach and flee from females. Most male advances were either ignored by females or elicited aggression from females toward males. Rates of male affiliative behavior toward females peaked around the time of conception. Although males behaved similarly toward young and old females in the highest social rank category, males directed more affiliative behavior toward older than younger females that were mid- and low-ranking. Multiple short mounts usually preceded a long mount, but intromission and ejaculation appeared to occur only during long mounts. Female receptivity was indicated by inhibited aggression toward the male and assumption of a distinctive receptive stance. The only behavior indicative of female proceptivity was following of the male by the female in mating contexts. Some males who sired cubs formed consortships with females whereas others did not, suggesting that individual male hyenas may adopt alternative reproductive tactics to attract and acquire mates. Our results also suggest that low fertility may be an important cost of female virilization in this species.

Nepotism is widespread among parents and offspring, and is typically associated with fundamental asymmetries; parents can usually do more to help their offspring than vice versa, andthe cost of a given nepotistic behavior is usually less for parents than for offspring. This may not be so among spotted hyenas (Crocuta crocuta); sires never achieve social rank equal to that of their cubs, to whom they provide no obvious paternal care. Nepotism by sires towards their cubs is thus socially constrained. However, the higher social status of cubs might offset cubs developmental disadvantages and permit nepotistic treatment of sires by offspring. We therefore sought to determine whether the interactions among spottedhyena cubs andad ult males were influencedby kinship, using long-term observations from one clan of spottedhyenas. Sires exhibitedno overt nepotism towards their cubs in most behaviors, but they did associate more closely with their daughters than with unrelated control females. Sires also associatedmore closely with their daughters than with their sons, with whom they associatedno more closely than they d idwith unrelatedcontrol males. Cubs favored their sires by directing less intense aggression towards them than towards unrelatedcontrol males. Cubs of both sexes also associatedmore closely with their sires than with control males after the cubs were independent of the clan’s communal den. Although sires evidently recognize their offspring, paternal nepotism by sires towards their cubs is weaker than filial nepotism by cubs towards their sires. The small size and immaturity of cubs thus appear to be weaker constraints on nepotism than is the low social status of their sires.

We used observations of known-age, free-ranging spotted hyenas (Crocuta crocuta) from a large social group to develop age-estimation models. A model based on tooth-eruption data estimates the ages of animals 10.0–15.5 (±1.1 SD) months old. We used tooth-wear data to estimate the ages of adult males ±4.9 months and ages of females ±22.6 months. Analysis of known and estimated ages shows that males usually disperse from their natal group when 24–60 months of age. Eight of 20 males whose fates were known lived in 3 groups over time, and at least 7 of 41 resident immigrant males appeared to arrive in the study group years after leaving their birthplaces. Thus, males of this species often engage in multiple dispersal events.

The purpose of this study was to document patterns of reproductive skew among male spotted hyenas (Crocuta crocuta), a species in which many normal mammalian sex roles are reversed. We used paternity determined from 12 microsatellite markers together with demographic and behavioral data collected over 10 years from a free-living population to document relationships among reproductive success (RS), social rank, and dispersal status of male hyenas. Our data suggest that dispersal status and length of residence are the strongest determinants of RS. Natal males comprise over 20% of the adult male population, yet they sire only 3% of cubs, whereas immigrants sire 97%. This reproductive advantage to immigrants accrues despite the fact that immigrants are socially subordinate to all adult natal males, and it provides a compelling ultimate explanation for primary dispersal in this species. High-ranking immigrants do not monopolize reproduction, and tenure accounts for more of the variance in male reproductive success than does social rank. Immigrant male hyenas rarely fight among themselves, so combat between rivals may be a relatively ineffectual mode of sexual selection in this species. Instead, female choice of mates appears to play an important role in determining patterns of paternity in Crocuta. Our data support a "limited control" model of reproductive skew in this species, in which female choice may play a more important role in limiting control by dominant males than do power struggles among males. Copyright 2002.

Arising from: O. P. Honer et al. , 798–801 (2007)10.1038/nature06040 ; Honer et al. reply In their investigation into whether female mate-choice drives male dispersal, Honer et al.1 argue that female spotted hyaenas (Crocuta crocuta) prefer mates whose tenure in the social group is less than the females’ age, to avoid paternal incest, and suggest that male dispersal reflects this preference. However, we are not persuaded that females choose mates on the basis of tenure because Honer et al.1 overlook the alternative hypothesis that dispersal status itself is important in female mate-choice2,3, such that females prefer immigrants over natal males. Like mate-choice based on tenure, choice based on dispersal status reduces the risk of incest.