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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-49747

Weingrill, T; Willems, E P; Zimmermann, N; Steinmetz, H W; Heistermann, M (2011). Species-specific patterns in fecal glucocorticoid and androgen levels in zoo-living orangutans (Pongo spp.). General and Comparative Endocrinology, 172(3):446-457.

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In contrast to most primate species, including the other great apes, orangutans maintain a fission–fusion social system in the wild without being part of a stable community. In zoos, however, they are kept in permanent groups, usually consisting of one adult male and several females. In zoo orangutans, we predict higher levels of glucocorticoids and androgens in the Bornean species compared to its congener from Sumatra, due to the much more solitary lifestyle of Bornean orangutans and the apparent higher frequency of male aggression directed towards females in this species in the wild. To compare hormone levels of the two orangutan species, we validated a fecal glucocorticoid and a fecal androgen assay. Subsequently, fecal samples from a total of 73 female and 38 male orangutans housed in 29 European zoos were analyzed to investigate the effect of species, social group size, age and (for female glucocorticoid levels) reproductive state and the presence of adult males on fecal hormone metabolite concentrations. The results of linear mixed effect models indicate that both male and female Bornean orangutans show a steeper increase in glucocorticoid levels with increasing group size than Sumatran orangutans. We therefore conclude that Sumatran zoo orangutans are better able to adjust to social housing conditions than their Bornean congeners. In addition, our analyses reveal higher glucocorticoid levels in lactating females of both species compared to non-lactating and juvenile females. Concerning androgen levels in males, our analyses revealed significantly higher concentrations in Bornean than Sumatran orangutans. These differences in both glucocorticoid and androgen output between the two species of orangutan are presumably linked to ecological and behavioral differences and could possibly be attributed to phenotypic plasticity. However, given that we found interspecific differences in hormone excretion in captivity, where both species live under very similar conditions, we conclude that this variation has a genetic basis.


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Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Anthropological Institute and Museum
05 Vetsuisse Faculty > Veterinary Clinic > Department of Small Animals
Dewey Decimal Classification:300 Social sciences, sociology & anthropology
Deposited On:23 Sep 2011 06:41
Last Modified:05 Apr 2016 15:01
Publisher DOI:10.1016/j.ygcen.2011.04.008
PubMed ID:21524655

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