Carlstead, K., & Brown, J. L. (2005). Relationships between patterns of Fecal corticoid excretion and behavior, reproduction, and environmental factors in captive black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros. Zoo Biol., 24(3), 215–232.
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.
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Cassinello, J., & Pieters, I. (2000). Multi-male captive groups of endangered dama gazelle: Social rank, aggression, and enclosure effects. Zoo Biol., 19(2), 121–129.
Abstract: A study carried out in four multi-male groups of captive dama gazelle (Gazella dama mhorr) characterized the social rank order of males and possible enclosure effects on aggression rate. A strong relationship between rank and age was found. The results also showed that dominant individuals in the two smallest enclosures were more aggressive than their herdmates, suggesting a more stressful environment, which might precipitate unstable or challenged hierarchies when the animals live in a more restricted enclosure. Subordinate males performed submissive responses at a higher frequency, irrespective of the size of the enclosure. The frequency of interactions between the gazelles, on the other hand, was affected by enclosure size, since high-ranking males showed higher values than low-ranking males in the two smallest enclosures. Frequencies of aggressive acts, retreats, and related interactions were similar in all the herds. Implications for the management of the species in captivity are discussed. Zoo Biol 19:121–129, 2000. © 2000 Wiley-Liss, Inc.
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GEYER CJ et al PY. 1989,. (). Gene survival in the Asian wild horse: II.Gene survival in the whole population, in subgroups, and through history. Zoo Biol, 8, 313–329.
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Geyer Cj, T. E. (1988). Gene survival in the Asian wild horse: I. Dependence of gene survival in the Calgary breeding group pedigree. Zoo Biol, 7, 313–327.
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Kirkpatrick, J. F., Lasley, B. L., & Shideler, S. E. (1990). Urinary steroid evaluations to monitor ovarian function in exotic ungulates. Zoo Biol, 9(5), 341–348.
Abstract: A direct enzyme immunoassay (EIA) for non-specific urinary progesterone (Po) metabolites, utilizing a non-specific monoclonal antibody against pregnanediol-3-glucuronide, was evaluated for the purpose of assessing luteal function in equids. Urinary pregnanediol-3-glucuronide (PdG) and immunoreactive PdG-like conjugate (iPdG) concentrations, indexed by creatinine, were compared to plasma Po concentrations in non-conceptive ovarian cycles through two ovulations in four mares. High-performance liquid chromatography (HPLC) of urine from lutealphase mares and a pregnant zebra revealed an absence of significant concentrations of PdG and the presence of at least three immunoreactive compounds, all of which were more polar than PdG. The concentration of iPdG in the mare ranged from a nadir of approximately 3 ng/mg Cr at the time of ovulation to nearly 400 ng/mg Cr at the mid-luteal-phase peak and paralleled plasma Po concentrations. This non-radiometric assay for iPdG permits the assessment of ovulation, luteal formation and function, and luteolysis in unprocessed urine samples from domestic mares. Data from a single zebra indicate this approach also will permit simplified and non-invasive longitudinal studies of ovarian function among a wide range of Equidae.
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