Natural Variation in Horn Size and Social Dominance and Their Importance to the Conservation of Black Rhinoceros

Conservation Biology (Impact Factor: 4.17). 07/2008; 12(3):708 - 711. DOI: 10.1111/j.1523-1739.1998.97207.x


1 Program in Ecology, Evolution, and Conservation Biology, 1000 Valley Road, University of Nevada, Reno, NV 89512, U.S.A., email


Available from: Joel Berger, Jun 17, 2014
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    • "Brown et al. [2001] validated fecal steroid metabolite assays to assess the reproductive status of 10.16 black and 6.13 white rhinoceroses in North America. The results confirmed earlier findings [Schwarzenberger et al., 1998; Patton et al., 1999; Hermes et al., 2002] that white rhino females exhibit numerous reproductive anomalies: some females have short cycles, some have long cycles, some have both short and long cycles, and some do not cycle at all. They suggested that stress as a cause of inconsistent gonadal activity needs to be evaluated in white rhinos. "
    [Show abstract] [Hide abstract] ABSTRACT: Mortality is high in zoo-housed black rhinoceros (Diceros bicornis), and the reproductive rates of captive white rhinoceros (Ceratotherium simum) are unsustainably low. To determine the possible role of stress in the causation of these problems, we analyzed weekly fecal samples collected for 1 year from black (10 males and 16 females) and white (six males and 13 females) rhinoceroses at 16 zoos for corticoid metabolite concentrations. Fecal corticoid profiles were examined in relation to behavior as rated by keepers in a questionnaire, luteal phase ovarian cycles of females (Brown et al., 2001), and socioenvironmental factors. We compared individual fecal corticoid profiles by examining hormone means and variability (i.e., standard deviation (SD) and coefficient of variation (CV)). For the black rhinos, higher mean corticoid concentrations were found at zoos where rhinos were maintained in enclosures that were exposed to the public around a greater portion of the perimeter. Higher variability in corticoid excretion was correlated with higher rates of fighting between breeding partners and higher institutional mortality rates. Black rhino pairs that were kept separated exhibited lower corticoid variability and less fighting activity when they were introduced during female estrous periods compared to pairs that were kept together every day. For white rhinos, significantly lower mean corticoids were found for individuals that rated higher on “friendliness to keeper.” Higher corticoid variability was found in noncycling as compared to cycling white rhino females. Noncycling females exhibited higher rates of stereotypic pacing and lower frequencies of olfactory behaviors. Interindividual differences in mean corticoids in both species appeared to be related to responsiveness to humans, whereas corticoid variability was related to intraspecific social relationships. More importantly, high corticoid variability appeared to be an indicator of chronic or “bad” stress, because of its association with potentially deleterious consequences in each species (i.e., fighting and mortality (black rhino), and reproductive acyclicity (white rhino)). Our results provide evidence that social stressors may cause chronic stress in black and white rhinos, and that this contributes to the captive-population sustainability problems observed in each species. Zoo Biol 0:1–18, 2005. © 2005 Wiley-Liss, Inc.
    Full-text · Article · May 2005 · Zoo Biology
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    [Show abstract] [Hide abstract] ABSTRACT: Recibido: 28 mayo 1999; aceptado: 28 julio 1999. Resumen. El capibara, Hydrochoerus hydrochaeris, es un roedor de 50 kg, herbívo-ro y gregario, que ha sido explotado en Venezuela desde tiempos coloniales. Hoy en día las poblaciones más saludables de la especie se mantienen en fincas privadas en las que se les aprovecha legalmente. En el artículo se plantea cómo la confluencia de factores ecológicos, culturales, económicos y legales contribuyen al éxito del pro-grama de manejo actual y producen la situación aparentemente paradójica en la que conservación y aprovechamiento parecen ir de la mano. También se discute la impor-tancia de ciertas variables sociales (tamaño de grupo, relación de sexos ("sex ratio"), dispersión) para el éxito del programa de manejo y para la conservación de la especie en Venezuela. Aunque se concluye que manejo y conservación pueden ser compati-bles, se advierte que el programa aplicado en Venezuela no es directamente transfe-rible a otras regiones o especies. Abstract. Behaviour, management and conservation: the case of capybaras in Ve-nezuela. Capybaras, Hydrochoerus hydrochaeris, are grazer, gregarious 50-kg rodents, which have been exploited in Venezuela since colonial times. Today, the healthiest populations of this species are found in private ranches where they are legally harvested. In this article, it is argued that the convergence of ecological, cultural, economic and legal factors promote the apparently paradoxical situation where exploitation and conservation go hand in hand. It is also discussed how certain social variables (group size, sex ratio, dispersal) are relevant to the management program and the conservation of the species in Venezuela. Although it is concluded that management and conservation are compatible, the article warns that the Venezuelan program is not directly transferable to other regions or species.
    Full-text · Article · Jan 1999
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