Evaluating the physiological and behavioral response of a male and female gorilla (Gorilla gorilla gorilla) during an introduction

Abstract

Prolonged stress responses can lead to infertility and death; therefore monitoring respective indicators like stress-related hormones and behaviors is an important tool in ensuring the health and well-being among zoo-housed animal populations. Changes in social structure, such as the introduction of a new conspecific, can be a source of stress. In April 2010, a sexually mature female western lowland gorilla (Gorilla gorilla gorilla) was brought to Lincoln Park Zoo (LPZ; Chicago, IL) from the Chicago Zoological Park (Brookfield, IL) for a breeding recommendation from the Gorilla Species Survival Plan. Fecal glucocorticoid metabolites (FGMs) were monitored in two gorillas prior to, during and immediately following the social introduction. Reproduction events, such ovarian cyclicity and pregnancy, were monitored using behavior and fecal progestagen metabolite (FPM; female) and fecal androgen metabolite (FAM; male) analyses. Mean (± standard error) FGM concentrations for the male were elevated (P = 0.002) during the introduction (20.61 ± 0.83 ng/g) compared to the pre- and post-introduction phases (11.31 ± 0.48 ng/g and 12.42 ± 0.65 ng/g, respectively). For the female, mean FGM concentrations were lower (P < 0.001) during the post-introduction (17.91 ± 1.07 ng/g) than during the pre- and introduction phases (30.50 ± 3.42 and 27.38 ± 1.51 ng/g, respectively). The female maintained normal FPM cyclicity throughout the study and became pregnant in the post-introduction phase. These results suggest the importance of both behavioral and physiological monitoring of zoo animals and demonstrate the potential stress that can occur during social introductions. Zoo Biol. 33:394-402, 2014. © 2014 Wiley Periodicals Inc.

Validating faecal glucocorticoid metabolite analysis in the Virunga mountain gorilla using a natural biological stressor

“…Males excreted lower levels than females, replicating results from a study in captive animals involving one adult male and one female western lowland gorilla (Jacobs et al ., 2014). There are three potential explanations for this difference.…”

“…This elevation is comparable to FGM analysis from captive western lowland gorillas following adrenocorticotrophic hormone challenge tests (Heistermann et al ., 2006; Nizeyi et al ., 2011a; Shutt et al ., 2012) and transportation between zoos for breeding purposes (e.g. an adult female showed a 7.6-fold increase in FGM; Jacobs et al ., 2014). Individual FGM profiles before and after inter-unit interactions showed that elevated FGM concentrations can quickly drop towards pre-event levels, implying that intensive faecal collection, especially around day 3 post-event, is crucial to assess the magnitude of any stressor.…”

“…During extreme rainy periods, we used a hair dryer to apply low heat to the hormone extracts (e.g. Loeding et al ., 2011; Jacobs et al ., 2014) for ~15 min each day to avoid moulding. Dry samples were capped and stored at −20°C until transport to the Davee Center for Epidemiology and Endocrinology at Lincoln Park Zoo (Chicago, IL, USA) for hormone analysis.…”

“…Faecal hormone metabolite analysis has been validated for both captive and wild western lowland gorillas ( Gorilla gorilla gorilla ; captive: Heistermann et al ., 2006; Nizeyi et al ., 2011a,b; Shutt et al ., 2012; Jacobs et al ., 2014; wild: Shutt et al ., 2012). Adrenocorticotrophic hormone challenge tests validated GC analysis techniques in zoo-housed western lowland gorillas (Heistermann et al ., 2006; Nizeyi et al ., 2011a; Shutt et al ., 2012; Jacobs et al ., 2014).…”

“…Adrenocorticotrophic hormone challenge tests validated GC analysis techniques in zoo-housed western lowland gorillas (Heistermann et al ., 2006; Nizeyi et al ., 2011a; Shutt et al ., 2012; Jacobs et al ., 2014). Performing an adrenocorticotrophic hormone challenge in mountain gorillas is impractical, because there is not an established captive population.…”