Abstract # 6332:

Scheduled for Saturday, June 20, 2015 11:00 AM-11:20 AM: (Cascade E) Oral Presentation


THE INFLUENCE OF BROWSE AVAILABILITY ON BEHAVIOR AND COGNITIVE BIAS IN CAPTIVE WESTERN LOWLAND GORILLAS (GORILLA GORILLA GORILLA)

G. A. Fuller1, J. Vonk2, M. McGuire2, A. Murray1 and S. Allard1
1Center for Zoo Animal Welfare, Detroit Zoological Society, 8450 W. 10 Mile Rd., Royal Oak, MI 48067, USA, 2Department of Psychology, Oakland University
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     We investigated the welfare impacts of browse availability in three male western lowland gorillas (Gorilla gorilla gorilla) at the Detroit Zoo. We systematically manipulated browse availability (Moraceae) over four consecutive two-week phases. We collected observational data on behavior (n = 60 hrs per gorilla) and assessed levels of “optimism” through a cognitive bias task using a simultaneous cue paradigm on a touch-screen computer. One-sample t-tests indicated that during the no browse phase, the gorillas selected the ambiguous stimulus (indicating positive interpretation) at a level greater than chance (M = 0.67, SD= 0.069; t2 = 4.25, p = 0.051); tests for all other phases were non-significant. Using a repeated measures ANOVA with study phase as the within-subjects factor, we found that the gorillas’ behavior varied significantly (Wilks’ lamda = 0.510, F63, 702.313 = 2.818, p < 0.001), and univariate tests showed significant changes in time spent processing (F1.725, 146.600 = 4.773, p = 0.013) and ingesting (F2.817, 239.419 = 11.548, p < 0.001) food, locomotion (F2.645, 224.809 = 6.321, p = 0.001), and rates of regurgitation and reingestion (F1.585, 134.697 = 3.320, p = 0.050). Regurgitation and reingestion was only absent during the daily browse condition. Our behavioral data suggest that increasing browse availability had positive impacts. The finding of the cognitive bias test may reflect greater motivation to seek reward when less browse was available.