Fred B. Bercovitch

Kyoto University, Kioto, Kyōto, Japan

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Publications (83)191.31 Total impact

  • Philip S. M. Berry, Fred B. Bercovitch
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    ABSTRACT: In cohesive social groups, travel progressions are often led by dominant or older individuals, but the leadership traits of individuals residing in flexible social systems are poorly known. Giraffe reside in herds characterized by fission–fusion dynamics frequently mediated by kinship. We analyzed 41 years (1971–2012) of longitudinal data collected from a community of Thornicroft's giraffe (Giraffa camelopardalis thornicrofti) living around South Luangwa National Park, Zambia, to assess the characteristics of herd leaders. Movement of giraffe in a single file progression was not associated with either season or time of day, but progressions were significantly more likely to occur when giraffe traveled in open areas. The oldest female in a herd was significantly more likely to be at the front position than expected, occupying the leadership niche on 79% of observations. We reason that matriarchal leadership in giraffe, as in African elephants, Loxodonta africana, is associated with resource learning. Giraffe societies are constructed on a heretofore unrecognized foundation that integrates relatedness and familiarity with matriarchal leadership in herd movement.RésuméDans des groupes sociaux cohésifs, les déplacements sont souvent conduits par des individus dominants ou plus âgés, mais les caractéristiques de meneurs d'individus qui vivent dans des systèmes sociaux flexibles sont peu connues. Les girafes vivent en hardes caractérisées par une dynamique de fission-fusion fréquemment déterminée par le degré de parenté. Nous avons analysé 41 années (1971–2012) de données longitudinales collectées dans une communauté de girafes de Thornicroft (Giraffa camelopardalis thornicrofti) vivant aux environs du Parc National de Luangwa Sud, en Zambie, pour évaluer les caractéristiques des meneurs de hardes. Les déplacements des girafes en file indienne n'étaient pas associés à une saison ou à un moment particulier de la journée, mais ils étaient significativement plus probables lorsque les girafes évoluaient dans des zones ouvertes. Il était significativement plus probable qu'attendu que ce soit la plus vieille femelle d'une harde qui soit en tête, occupant la niche de leader dans 79% des observations. Nous en déduisons que le leadership matriarcal chez les girafes, comme chez les éléphants d'Afrique (Loxodonta africana), est lié à l'apprentissage des ressources. Les sociétés de girafes sont construites sur une base jusqu'ici non reconnue qui intègre le degré de parenté et de connaissance au leadership matriarcal pour le déplacement des hardes.
    African Journal of Ecology 09/2014; · 1.00 Impact Factor
  • Fred B. Bercovitch, Philip S. M. Berry
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    ABSTRACT: Temporary all-male social groups are formed in a number of animal species. We examined 34 years of data collected from 36 male Thornicroft's giraffe in the Luangwa Valley, Zambia, to test a set of predictions related to five possible functions of all-male herds (predator protection, practicing aggressive skills, prolonging life, nutritional demands and resource learning). We found that all-male herds were significantly smaller than mixed-sex herds, usually contained a mature bull, and were not dependent upon season or habitat. Dyadic associations between males in single sex herds were quite weak, with <25% of potential male dyads sighted together in an all-male herd. Our data are best explained as a resource learning strategy adopted by males to obtain more extensive knowledge about the habitat, including both food and female distribution. However, other benefits in the form of predator protection, dietary intake and sharpening competitive skills for future contests over estrous females also seem to mediate formation of giraffe all-male groups. We conclude that the primary advantage of roaming in all-male herds changes during the life history of males.RésuméDes groupes sociaux composés uniquement de mâles se forment chez un certain nombre d'espèces animales. Nous avons examiné 36 années de données récoltées sur 36 girafes de Thornicroft mâles dans la vallée de la Luangwa, en Zambie, afin de vérifier un ensemble de prévisions concernant cinq fonctions possibles de ces hordes de mâles (protection contre les prédateurs, exercice des capacités d'agression, prolongation de la vie, besoins nutritionnels et apprentissage des ressources disponibles). Nous avons constaté que les hordes composées exclusivement de mâles étaient significativement plus petites que les hordes mixtes, qu'elles comprenaient d'habitude un mâle adulte et qu'elles ne dépendaient ni de la saison ni de l'habitat. Des associations en dyades dans les hordes de mâles étaient plutôt fragiles, avec seulement 25% de dyades potentielles observées ensemble. Nos données s'expliquent mieux s'il s'agit d'une stratégie d'apprentissage des ressources que les mâles adoptent pour acquérir une connaissance plus complète de l'habitat, y compris de la distribution de la nourriture et des femelles. Pourtant, d'autres avantages comme la protection contre les prédateurs, la consommation de nourriture et l'amélioration des qualités de compétition en vue des combats pour des femelles en chaleur semblent aussi influencer en faveur de la formation de groupes de girafes mâles. Nous en concluons que le premier avantage de groupes composés exclusivement de girafes mâles change au cours du cycle vital des mâles.
    African Journal of Ecology 08/2014; · 1.00 Impact Factor
  • IPS XXV Congress, Hanoi, Vietnam; 08/2014
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    ABSTRACT: The ability to determine hormonal profiles of primate populations using non-invasive techniques can help to monitor physical fitness, stress, and physiological responses to environmental changes. We investigated fecal glucocorticoids (fGC) and DHEAS concentrations in captive Japanese macaques (Macaca fuscata) in relation to environmental, biological, and social factors. The subjects were female Japanese monkeys from 4 months to 31 years old housed in captivity (27 in social groups and 12 in single cages). Fecal samples were collected from all females, and behavioral data from the social groups during the mating season and the following birth season. Hormonal concentrations were analyzed by enzyme immunoassay. Our results revealed that both fGC and fecal DHEAS concentrations are higher in females housed indoors in single cages than in those living outdoors in social groups. We also found that fGC concentrations were higher in the cycling females during the mating (winter) season than the lactating females in the birth (spring) season. Age was negatively associated to both fGC and fecal DHEAS levels, but the relationship between age and fecal DHEAS was more evident in females housed indoors in single cages than in females housed in outdoor social groups. We did not observe any association of dominance rank with either fecal DHEAS or fGC. This study showed that measurement of fecal DHEAS and fGC can be a good method to assess stress in Japanese macaques. These findings provide insights about the physiology of these two adrenal hormones in female Japanese macaques, which can be applied to wild populations and is fundamental for captive management and conservation biology. Am. J. Primatol. © 2014 Wiley Periodicals, Inc.
    American Journal of Primatology 05/2014; · 2.14 Impact Factor
  • F. B. Bercovitch, P. S. M. Berry
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    ABSTRACT: In many mammalian species, animals form subunits within larger groups that are often associated with kinship and/or age proximity. Kinship mediates fission/fusion social dynamics of giraffe herds, but the role of age proximity has been unexamined. Here, we analyze 34 years of data from a population of Thornicroft's giraffe, Giraffa camelopardalis thornicroftii, living in Zambia in order to assess the extent to which age proximity influences herd composition. We show for the first time that calves born into the same cohort have stronger social associations than calves born into different age cohorts, and that the strength of their association is independent of the strength of maternal associations. Duration of time co-resident in the population did not influence the strength of social associations. Mothers and adult daughters have significantly stronger social associations than do unrelated adult females. We suggest that giraffe have evolved mechanisms for fostering the formation of social associations with similar aged non-kin. Giraffes live in a complex society incorporating both kinship and age proximity as factors modulating the formation of social associations that underlie the fission/fusion dynamics of their flexible herd structure.
    Journal of Zoology 08/2013; 290(4). · 1.95 Impact Factor
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    ABSTRACT: Dehydroepiandrosterone (DHEA) and its sulfate, DHEAS, are the most abundant steroid hormones in primates, providing a large reservoir of precursors for the production of androgens. DHEAS levels decline with age in adult humans and nonhuman primates, prompting its consideration as a biomarker of senescence. However, the mechanisms responsible for this age-related decrease and its relationship to reproduction remain elusive. This research investigated DHEAS concentrations in fecal samples in order to determine age-related changes in captive Japanese macaques, as well as to assess the possible influence of seasonality. The subjects were 25 female Japanese macaques (2 weeks to 14 years-old) housed outdoors in social groups at the Primate Research Institute. We collected three fecal samples from each animal during the breeding season (October to December) and three additional samples from adult females during the non-breeding season (May to June). The hormonal concentrations were determined using enzyme immunoassay. DHEAS concentration was negatively correlated with age, but we did not find a significant difference between breeding and non-breeding seasons. Neonatal macaques had the highest DHEAS concentrations of all age groups. We suggest that elevated neonatal DHEAS is possibly a residue from fetal adrenal secretion and that, as in humans, it might assist in neurobiological development.
    General and Comparative Endocrinology 06/2013; · 2.82 Impact Factor
  • Fred B. Bercovitch, Philip S. M. Berry
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    ABSTRACT: AbstractA variety of social systems have evolved as a consequence of competition and cooperation among individuals. Giraffe (Giraffa camelopardalis sp.) societies are an anomaly because the dearth of long‐term data has produced two polar perspectives: a loose amalgamation of non‐bonded individuals that sometimes coalesce into a herd and a structured social system with a fission–fusion process modifying herd composition within a community. We analysed 34 years of data collected from a population of Thornicroft's giraffe (G. c. thornicrofti, Lydekker 1911) residing in South Luangwa, Zambia, to establish the nature of giraffe society. Our sample consisted of 52 individually recognized animals. We found that giraffe herd composition is based upon long‐term social associations that often reflect kinship, with close relatives significantly more likely than non‐relatives to establish herds. Mother/offspring dyads had the strongest associations, which persisted for years. Giraffe live in a complex society characterized by marked flexibility in herd size, with about 25% of the variance in herd composition owing to kinship and sex. We suggest that giraffe herds share many characteristics of fission–fusion social systems and propose that sophisticated communication systems are a crucial component regulating subgroup dynamics.
    African Journal of Ecology 06/2013; 51(2). · 1.00 Impact Factor
  • Fred B. Bercovitch
    African Journal of Ecology 06/2013; 51(2). · 1.00 Impact Factor
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    ABSTRACT: In principle, conservation planning relies on long-term data; in reality, conservation decisions are apt to be based upon limited data and short-range goals. For the koala (Phascolarctos cinereus), frequently reliance is made on the assumption that indirect signs can be used to indicate behavioural preferences, such as diet choice. We examined the relationship between the use of trees by koalas and the presence of scats beneath those trees. Tree use was associated with scat presence on 49% of occasions when koalas were radio-tracked in both central Queensland (n = 10 koalas) and south-east Queensland (n = 5 koalas), increasing to 77% of occasions when trees were rechecked the following day. Koala densities were correlated with scat abundance at sites with koala density between ~0.2 and 0.6 koalas per hectare. Our results confirm that scat searches are imprecise indicators of tree use by koalas, but demonstrate that these searches can be used, with caveats, to estimate koala population densities. We discuss how errors in estimating or applying predictive model parameters can bias estimates of occupancy and show how a failure to validate adequately the assumptions used in modelling and mapping can undermine the power of the products to direct rational conservation and management efforts.
    Australian Mammalogy 03/2013;
  • Fred B. Bercovitch
    International Journal of Primatology 12/2012; 33(6). · 1.99 Impact Factor
  • Fred B. Bercovitch
    Primates 10/2012; 53(4). · 1.40 Impact Factor
  • P. S. M. Berry, F. B. Bercovitch, Andrew Kitchener
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    ABSTRACT: Much of the information available about the life history of the giraffe, Giraffa camelopardalis, is derived from captive studies or short‐term field studies. The coat colour of male giraffes, especially the blotches, darkens with age, but no studies have systematically mapped the colour transition with chronological age based on long‐term data. We examine the value of using darkening coat colour as a biomarker of male age. We analyzed 33 years of data from 36 male Thornicroft's giraffes, G. c. thornicroftii, living in Zambia in order to document key milestones in male development. We found that the change in male pelage colouration takes an average of 1.8 years and that males are completely covered with coal‐black blotches at an average age of 9.4 years. Using lifetime data on male deaths and disappearances, combined with cross‐sectional records on coat‐colour transformation, we conclude that the average age of death among male giraffes is about 16 years old. The maximum lifespan of male giraffes is about 22 years compared with a maximum lifespan of about 28 years for female giraffes. We conclude that the possible proximate mechanisms and adaptive significance of male coat‐colour changes should be studied in more detail.
    Journal of Zoology 07/2012; 287(3). · 1.95 Impact Factor
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    ABSTRACT: Acoustic communication mediates sociality in a variety of animals. One of the more ubiquitous vocal signals to have evolved is the sexual advertisement call of males. Koala (Phascolarctos cinereus) males emit a sonorous bellow call during the breeding season, but no detailed studies of the calling context appear to have been published. We used a novel remote sound detection network to monitor koala bellowing while simultaneously collecting koala behavioral data using collar-mounted GPS units. Our approach enabled us to examine fine scale temporal variation in vocalization and spatial movements of free-ranging koalas without direct behavioral observations. Bellow occurrence was susceptible to weather conditions, with fewer calls occurring when wind speed and temperatures were high. The number of bellow vocalizations recorded during an annual period mirrored breeding activity, with nearly all male bellows recorded during peak mating season. The distance traveled by koalas and the occurrence of koala bellows both peaked around midnight, but only female travel distance during the breeding season was temporally correlated with bellow occurrence. We conclude that environmental factors might trigger male bellowing to launch the breeding season and that these male vocal signals function more to attract females than to repel males. Female mate selection is probably an important component of male reproductive success in koalas, which is partly mediated by male bellow characteristics. Copyright 2011, Oxford University Press.
    Behavioral Ecology 04/2011; 22(2):372-377. · 3.16 Impact Factor
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    William A. H. Ellis, Fred B. Bercovitch
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    ABSTRACT: Sexual selection is often characterized by polygynous breeding systems, size dimorphism, and skewed operational sex ratios. Koalas are sexually dimorphic in multiple domains, yet are absent from the literature on sexual selection and the structure of their mating system is unclear. We provide the first documentation of the strength of sexual selection in koalas by using microsatellite markers to identify sires. We combine the genetic data with morphological data in order to assess the role of body size in regulating reproductive output. During our 4-year study, 37% of males were identified as possible sires. Males were significantly larger than females, with sires heavier than non-sires. Male body mass correlated with annual reproductive output, with Crow’s Index of Opportunity for Selection revealing that variation in male reproductive success was threefold higher than that of females. Since it appears that male koalas rarely engage in physical confrontations over access to females, size dimorphism could be based upon non-agonistic competition and/or female mate choice. We propose that size dimorphism in koalas evolved as a consequence of endurance rivalry promoting vocal sexual advertisements that attract females. We suggest that female choice is a key mediator of male reproductive output. KeywordsKoalas–Sexual selection–Size dimorphism–Reproductive success–Mate choice–Microsatellite DNA
    Behavioral Ecology and Sociobiology 01/2011; 65(6):1229-1235. · 3.05 Impact Factor
  • Fred B. Bercovitch, Philip S.M. Berry
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    ABSTRACT: Ecological factors have a pervasive impact on animal population sizes and the structure of their social systems. In a number of ungulate species, predator pressure exerts a major influence on group size. Given that giraffe (Giraffa camelopardalis) live in an extremely flexible social system, and that breeding is nonseasonal, they are an ideal species for examining how ecological variables contribute to fluctuations in herd size. We present an analysis of 34 years of data on a population of Thornicroft’s giraffe (G. c. thornicrofti Lydekker 1911) that reveal how herd size changes with season and habitat. Sex differences in herd size were apparent, with bulls often travelling as singletons, whereas cows were generally observed with conspecifics. Herds were larger during the wet than dry season, but herd size changed in a parallel fashion across habitats. Giraffe herds were smaller in woodland and thicket areas than in open habitats, regardless of season. We suggest that the regular fluctuations in herd size among giraffe indicate a fission/fusion social system embedded within a larger social community. We conclude that changes in herd size among giraffe reflect a dynamic process regulated by individuals adjusting the number of associates based upon an interaction of foraging, reproductive, social and antipredator strategies.RésuméLes facteurs écologiques ont un effet généralisé sur la taille des populations animales et sur la structure de leurs systèmes sociaux. Chez un certain nombre d’espèces d’ongulés, la pression des prédateurs exerce une influence majeure sur la taille des groupes. Étant donné que la girafe Giraffa camelopardalis vit dans un système social extrêmement flexible, et que la reproduction n’y est pas saisonnière, c’est une espèce idéale pour examiner comment des variables écologiques contribuent aux fluctuations de la taille de la harde. Nous présentons une analyse couvrant 34 années de données sur une population de girafes de Thornicroft, G. c. thornicrofti Lyddeker 1911, qui révèle comment la taille de la harde change avec les saisons et l’habitat. La différence des sexes dans la taille des hardes était visible, les mâles voyageant souvent en solitaires alors que les femelles étaient généralement observées avec des congénères. Les hardes étaient plus grandes en saison des pluies qu’en saison sèche, mais la taille des hardes changeait, dans le même temps, selon les habitats. Les hardes de girafes étaient plus petites en forêt et dans les zones arbustives que dans les habitats ouverts, quelle que soit la saison. Nous suggérons que, chez les girafes, la taille des hardes indique une fission/fusion du système social ancré dans une communauté sociale plus large. Nous concluons que les changements de taille de hardes chez les girafes reflètent un processus dynamique régulé par des individus qui ajustent le nombre de leurs associés selon une interaction des stratégies alimentaires, reproductives, sociales et défensives contre les prédateurs.
    African Journal of Ecology 11/2010; 48(4):962 - 971. · 1.00 Impact Factor
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    ABSTRACT: Two central concerns for elephant husbandry and management are whether zoological enclosures are appropriately sized and the degree to which naturalistic exercise and activity are observed in such enclosures. In order to address these issues, accurate data on the daily walking distance of elephants both in situ and ex situ are necessary. We used an accelerometer, a pedometer that measures step count and activity level, to estimate walking distance in African elephants (Loxodonta africana) at the San Diego Zoo's Wild Animal Park. The accelerometer was worn simultaneously with a GPS unit that recorded actual walking distance. Estimates of walking distance were extrapolated from the accelerometer and compared with actual distances determined by GPS data. The accelerometer was found to overestimate step count, and subsequently walking distance, by including false counts of steps. Extrapolating walking distance based upon stride length measurements did not match actual GPS walking distance. However, activity level output from the accelerometer significantly correlated with actual GPS walking distance. In addition, we report that the rate of movement is comparable to that reported in other zoological settings. We provide a linear regression equation that can be utilized by other institutions to estimate daily walking distance of elephants in their collection who are outfitted with accelerometers.
    Zoo Biology 11/2010; 30(5):579-91. · 0.85 Impact Factor
  • Fred B Bercovitch, Jeff Andrews
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    ABSTRACT: A recurrent issue confronted by zoos is the extent to which animals living ex situ have life history profiles representative of those living in situ. The lengthy lifespan of African elephants hinders collecting proper comparative data, but enough information has been published to conduct preliminary analyses comparing the developmental profile of zoo and wild African elephants on their first day of life. We show that calves born in a zoo stand and walk on their own for the first time at the same age as those born in the wild. Calves born in the zoo take a little longer until first successful nursing, but the difference in age between wild and zoo is not statistically significant. Male and female calves born in zoos develop at the same pace, with data insufficient to compare with wild-born calves. We conclude maternal parity has an effect on the age of first nursing, but not on first standing or walking, because the initiation of suckling requires coordination between two animals. We suggest that available evidence indicates that calves born in the wild and in zoos develop at comparable rates.
    Zoo Biology 03/2010; 29(2):120-6. · 0.85 Impact Factor
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    ABSTRACT: Koalas specialize on Eucalyptus leaves, but also feed selectively. Food choice is not random, but depends on various factors that are not well understood, although most research has focused on the role of secondary plant compounds. We studied the feeding choices of four adult male koalas housed at the San Diego Zoo. All subjects had a choice of nine types of Eucalyptus leaves over the eight-week study. The most preferred species was E. camuldulensis, but individual males exhibited different feeding preferences. We conclude that food selectivity among koalas is probably due to multiple factors, rather than only a consequence of secondary plant chemicals. A combination of intrinsic factors, such as developmental trajectory and reproductive state, as well as extrinsic factors, such as leaf chemical fingerprint and moisture, probably interact to shape koala foraging preferences. Koalas forage almost exclusively on Eucalyptus species, but have evolved an adaptive flexibility, enabling them to exploit various Eucalyptus species.
    Zoo Biology 02/2010; 30(1):52-8. · 0.85 Impact Factor
  • Journal of Mammalogy 01/2010; · 2.23 Impact Factor

Publication Stats

2k Citations
191.31 Total Impact Points


  • 2010–2014
    • Kyoto University
      • Primate Research Institute
      Kioto, Kyōto, Japan
  • 2013
    • Japan Wildlife Research Center
      Edo, Tōkyō, Japan
  • 2002–2010
    • San Diego Zoo
      San Diego, California, United States
  • 1987–2009
    • Wisconsin National Primate Research Center
      Madison, Wisconsin, United States
  • 2002–2008
    • Center for Advanced Studies on Puerto Rico and the Caribbean
      Punta Santiago, Humacao, Puerto Rico
  • 2006–2007
    • Duke University
      • Department of Biology
      Durham, North Carolina, United States
  • 1993–2006
    • University of Puerto Rico, Medical Sciences Campus
      • Department of Biochemistry
      San Juan, San Juan, Puerto Rico
  • 1991–2005
    • American University in Puerto Rico
      • Caribbean Primate Research Center
      Rio Rico, Arizona, United States
  • 2001–2004
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
    • German Primate Center
      Göttingen, Lower Saxony, Germany
  • 1998
    • Charité Universitätsmedizin Berlin
      • Institute of Medical Genetics and Human Genetics
      Berlin, Land Berlin, Germany
  • 1997
    • University of Puerto Rico at Ponce
      Ponce, Ponce, Puerto Rico
  • 1986–1988
    • University of Wisconsin–Madison
      Madison, Wisconsin, United States