Abstract # 110:

Scheduled for Sunday, September 14, 2014 02:00 PM-02:15 PM: Session 17 (Mary Gay) Oral Presentation


DOMINANCE, GLUCOCORTICOIDS, AND SPATIAL COMPRESSION IN A CAPTIVE GROUP OF BACHELOR GORILLAS (GORILLA GORILLA GORILLA)

L. Torgerson-White1, M. McGuire2, S. Allard1 and C. Bennett3
1Detroit Zoological Society, 8450 W. 10 Mile Rd, Royal Oak, MI 48067, USA, 2Oakland University, 3Journal of Applied Animal Welfare Science
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     The Detroit Zoo is home to three male gorillas who have recently become silverbacks and are housed outdoors, indoors, or with access to both spaces depending on the weather. In order to examine the impact of housing on stress, 519 hours of behavioral data, 658 fecal samples, and 2248 saliva samples were collected from January 2012-March 2014. Behavioral data was collected using continuous sampling for social behaviors and scan sampling for activity budget behaviors. Generalized linear models revealed lowest levels of agonism when the gorillas were outside; with a 10% increase when inside and a 29% increase when accessed to both habitats (p<0.001 and p<0.01). Dominance began to shift during the study and linear models revealed increasing fecal glucocorticoids in the newly dominant individual as agonism and his dominance status increased (p=0.001 and p=0.04). Salivary cortisol was higher when the gorillas were inside (ANOVA, p=0.0005), a trend driven by subordinate males. Furthermore, the two gorillas who were vying for dominance experienced elevated salivary cortisol during months of higher agonism (Spearman’s correlations, p = 0.006 and p = 0.04). Preliminary analysis of data comparing the three conditions within the same month suggests that the trends are not tied to season, but do depend on the individual. These results suggest that gorilla welfare may increase when given prolonged outdoor access, but that dominance status mediates this impact.