In captivity

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Stress

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Stresses have been known to cause both physiological and behavioral chronic issues for captive species including, but not limited to altered reproductive cycling and behavior, reduced immune responses, disrupted hormone and growth levels, reduced body weight, heightened abnormal activities and aggression, and decreased exploratory behavior with increased hiding behaviors. [1] Such stress reactions could be caused by sounds, light conditions, odors, temperature and humidity conditions, material make-up of enclosures, habitat size constraints, lack of proper hiding areas, forced closeness to humans, routine husbandry and feeding conditions, or abnormal social groups to name a few.[1]

Stereotypic Behaviors

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Stereotypic behaviors are abnormal or compulsive behaviors. In gorillas, such common aberrant behaviors include eating disorders—such as regurgitation, reingestion, and coprophagy—self injurious or conspecific aggression, pacing, rocking, sucking of fingers or lip smacking, and overgrooming [2] Negative vigilance of visitor behaviors have been identified as starting, posturing, and charging at visitors. [3] Groups of bachelor gorillas containing young silverbacks have significantly higher levels of aggression and wounding rates than mixed age and sex groups.[4] [5]

Exhibit Modifications

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Use of both internal and external privacy screens on exhibit windows has been shown to alleviate stresses from visual effects of high crowd densities, leading to decreased stereotypic behaviors in the gorillas. [3] Playing naturalistic auditory stimuli as opposed to classical music, rock music, or no auditory enrichment (which allows for crowd noise, machinery, etc. to be heard) has been noted to reduce stress behavior as well.[6] Enrichment modifications to feed and foraging, where clover-hay is added to an exhibit floor, decrease stereotypic activities while simultaneously increasing positive food-related behaviors.[3]

Assessment

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Recent research on captive gorilla welfare emphasizes a need to shift to individual assessments instead of a one size fits all group approach to understanding how welfare increases or decreases based on a variety of factors.[5] Individual characteristics such as age, sex, personality, and individual histories are essential in understanding that stressors will affect each individual gorilla and their welfare differently.[5][3]

References

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  1. ^ a b Morgan K, Tromborg C. Sources of stress in captivity. Applied Animal Behaviour Science. 2007 [accessed 2015 Oct 14];102(3-4):262-302.
  2. ^ Wells, D.L. (2005) A note on the influence of visitors on the behaviour and welfare of zoo-housed gorillas. Applied Animal Behaviour Science, 93, pp. 13- 17
  3. ^ a b c d Clark F, Fitzpatrick M, Hartley A, King A, Lee T, Routh A, Walker S, George K. Relationship between behavior, adrenal activity, and environment in zoo-housed western lowland gorillas (Gorilla gorilla gorilla). Zoo Biology. 2011;31(3):306-321
  4. ^ Leeds A, Boyer D, Ross S, Lukas K. The effects of group type and young silverbacks on wounding rates in western lowland gorilla ( Gorilla gorilla gorilla ) groups in North American zoos. Zoo Biology. 2015 [accessed 2015 Oct 12];34(4):296-304.
  5. ^ a b c Stoinski T, Jaicks H, Drayton L. Visitor Effects on the Behavior of Captive Western Lowland Gorillas: The Importance of Individual Differences in Examining Welfare. Zoo Biology. 2011;31(5):586-599.
  6. ^ Robbins L, Margulis S. The effects of auditory enrichment on gorillas. Zoo Biology. 2014 [accessed 2015 Oct 12];33(3):197-203.

Other Task To Do

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Move the In Captivity sub section to the Behavior Section move “Adult male gorillas are prone to cardiomyopathy, a degenerative heart disease.” into disease section from introduction