Relationships between patterns of Fecal corticoid excretion and behavior, reproduction, and environmental factors in captive black (Diceros bicornis) and white (Ceratotherium simum) rhinoceros

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 24: 215-232, 2005.

Corticosteroid-Induced Suppression of in Vitro Lymphocyte Proliferation in Four Captive Rhinoceros Species

“…2 Finally, several publications have reported higher corticosteroid concentrations in black rhinoceroses compared with the other rhinoceros species in captivity. 6,7,23 Therefore, a hypothesis gaining momentum is that stress-related increases in glucocorticoid production predispose black rhinoceroses to disease.…”

“…In support of this hypothesis are recent reports correlating elevated fecal corticoid production with specific captive conditions, mortality, and disease. 6,7 The underlying mechanism of stress-induced disease susceptibility is suppression of the immune system by chronic elevated circulating steroids. Fatal fungal infections are not uncommon in humans with high levels of endogenously produced corticosteroids or on corticosteroid therapy, 9,24 and the same likely holds true for the rhinoceros.…”

Novel Environmental Enrichment May Provide a Tool for Rapid Assessment of Animal Personality: A Case Study With Giant Pandas (Ailuropoda melanoleuca)

“…All coefficients were highly significant (p < .001). We then calculated coefficients of variation (CVs) for each behavioral characteristic for each panda separately so that we could compare the variability in ratings across different characteristics while controlling for the mean (Carlstead & Brown, 2005). Characteristics with a CV of 0.5 or greater in either pair of pandas were discarded from further analysis.…”

The visitor effect in petting zoo-housed animals: Aversive or enriching?

“…These include decreased social behaviour (Chamove et al, 1988, Glatston et al, 1984, Mallapur et al, 2005, Wood, 1998, increased abnormal behaviour (Blaney and Wells, 2004, Chamove et al, 1988, Mallapur and Chellam, 2002, Mallapur et al, 2005, Skyner et al, 2004, Wells, 2005 and increased aggression (Blaney and Wells, 2004, Chamove et al,1 988, Glatston et al, 1984, Kuhar, 2008, Mitchell et al, 1991, Wells, 2005. More recently, physiological changes indicative of decreased welfare have been reported in relationship to visitor-related variables in spider monkeys (Ateles geoffroyii rufiventris; Davis et al, 2005) and black rhinoceros (Dicornis bicornis; Carlstead and Brown, 2005).…”