Examining the dual hormone hypothesis in wild male mountain gorillas (Gorilla beringei beringei).

The Challenge Hypothesis is an influential framework for understanding how androgens are involved in the promotion of competitive behavior during mating-related challenges and has been tested extensively in studies across scientific disciplines. Mixed support in psychological research led scholars to develop the Dual Hormone Hypothesis as a potential path forward, which argues that glucocorticoids moderate the relationship between androgens and status-striving. In the current study, we examine the Challenge Hypothesis and the Dual Hormone Hypothesis in wild male mountain gorillas, representing the first time the latter hypothesis has been tested in a non-human primate. In a sample of 30 adult males comprising over 600 days of observation, we find some limited support for the Challenge Hypothesis. Greater daily rates of targeted aggression toward other adult males corresponded to higher fecal androgen metabolites 1-2 days following observations, though this pattern did not fully generalize to dominance rank or other competitive behaviors examined. However, we find no support for the Dual Hormone Hypothesis: neither dominance rank nor any category of competitive behavior was predicted by the interaction between androgens and glucocorticoids. We close by discussing how this initial investigation might be leveraged toward the development of an expanded Dual Hormone Hypothesis that draws on the large evidence base in primate behavioral ecology.

Gut bacterial composition shows sex-specific shifts during breeding season in ex situ managed black-footed ferrets.

The gut microbiome of mammals engages in a dynamic relationship with the body and contributes to numerous physiological processes integral to overall health. Understanding the factors shaping animal-associated bacterial communities is therefore paramount to the maintenance and management in ex situ wildlife populations. Here, we characterized the gut microbiome of 48 endangered black-footed ferrets (Mustela nigripes) housed at Smithsonian's National Zoo and Conservation Biology Institute (Front Royal, Virginia, USA). We collected longitudinal fecal samples from males and females across two distinct reproductive seasons to consider the role of host sex and reproductive physiology in shaping bacterial communities, as measured using 16S rRNA amplicon sequencing. Within each sex, gut microbial composition differed between breeding and non-breeding seasons, with five bacterial taxa emerging as differentially abundant. Between sexes, female and male microbiomes were similar during non-breeding season but significantly different during breeding season, which may result from sex-specific physiological changes associated with breeding. Finally, we found low overall diversity consistent with other mammalian carnivores alongside high relative abundances of potentially pathogenic microbes such as Clostridium, Escherichia, Paeniclostridium, and (to a lesser degree) Enterococcus - all of which have been associated with gastrointestinal or reproductive distress in mammalian hosts, including black-footed ferrets. We recommend further study of these microbes and possible therapeutic interventions to promote more balanced microbial communities. These results have important implications for ex situ management practices that can improve the gut microbial health and long-term viability of black-footed ferrets.

An empirical comparison of several commercial enzyme immunoassays for the non-invasive assessment of adrenocortical and gonadal function in mountain gorillas.

Wildlife researchers seeking to non-invasively examine endocrine function in their study species are presented with a dense and technical 'garden of forking paths' to navigate between collecting a biological sample and obtaining a final measurement. In particular, the choice of which enzyme immunoassay (EIA) to use with collected fecal samples, out of the many options offered by different manufacturers and research laboratories, may be one of the most consequential for final results. However, guidance for making this decision is still emerging. With this gap in mind, we performed a head-to-head comparison of results obtained from four different EIAs for fecal glucocorticoid metabolites (FGCMs), and three different EIAs for fecal androgen metabolites (FAMs), applied to the same set of fecal samples collected from the mountain gorillas (Gorilla beringei beringei) monitored by the Dian Fossey Gorilla Fund in Volcanoes National Park, Rwanda. We provide a) an analytical validation of the different EIAs via tests of parallelism and linearity; b) an estimate of inter-assay correlation between EIA kits designed for the same metabolites; and c) a test of the kits' ecological validity, in which we examine how well each captures endocrine changes following events that theory predicts should result in elevated FGCM and/or FAM concentrations. Our results show that kits differ to some degree in their performance; at the same time, nearly all assays exhibited at least moderate evidence of validity and covariance with others for the same analyte. Our findings, which differ somewhat from similar comparisons performed in other species, demonstrate the need to directly assess assay performance in a species- and context-specific manner as part of efforts to develop the burgeoning discipline of wildlife endocrinology.

Designing an assay to evaluate behavioral responses to opposite-sex conspecifics in the endangered black-footed ferret (Mustela nigripes).

The endangered black-footed ferret (ferret; Mustela nigripes) is a North American carnivore that is actively managed to reestablish self-sustaining wild populations. Behavioral abnormalities have been reported in the breeding program and may be a limiting factor for the species' success. Our goal was to design and test an assay that examines the ferret's exploratory response to odor cues in the form of soiled bedding from opposite-sex conspecifics. Across two breeding seasons, males and females were tested using a T-maze that connected their home nest box to two novel nest boxes containing two different conspecific's soiled bedding. For a control, we provided two clean bedding samples. We ran linear mixed models to determine the effect of sex, type of odor cue (soiled, clean), and order of trial (first, second) on time exploring and proportion of that time spent in each behavior. Ferrets spent the majority of time in the novel nest boxes sniffing (44%), standing alert (27%) and scratching (14%). Males explored for longer than females; however, both displayed similar behaviors. Type of cue influenced behavior, with ferrets sniffing more among soiled cues than clean cues. Habituation to the assay was also observed, with less exploration and more standing alert during the second trial of the day. This study is the first step in characterizing the ferret's exploratory response and provides information regarding vital investigatory and vigilance behaviors. The continual development of this assay to further evaluate reproductive and mate choice behaviors will facilitate more successful breeding of the species.

The Gombe Ecosystem Health Project: 16 years of program evolution and lessons learned.

Infectious disease outbreaks pose a significant threat to the conservation of chimpanzees (Pan troglodytes) and all threatened nonhuman primates. Characterizing and mitigating these threats to support the sustainability and welfare of wild populations is of the highest priority. In an attempt to understand and mitigate the risk of disease for the chimpanzees of Gombe National Park, Tanzania, we initiated a long-term health-monitoring program in 2004. While the initial focus was to expand the ongoing behavioral research on chimpanzees to include standardized data on clinical signs of health, it soon became evident that the scope of the project would ideally include diagnostic surveillance of pathogens for all primates (including people) and domestic animals, both within and surrounding the National Park. Integration of these data, along with in-depth post-mortem examinations, have allowed us to establish baseline health indicators to inform outbreak response. Here, we describe the development and expansion of the Gombe Ecosystem Health project, review major findings from the research and summarize the challenges and lessons learned over the past 16 years. We also highlight future directions and present the opportunities and challenges that remain when implementing studies of ecosystem health in a complex, multispecies environment.

RECOMBITEK CANINE DISTEMPER VACCINE AS AN ALTERNATIVE FOR PUREVAX DISTEMPER VACCINE IN ENDANGERED BLACK-FOOTED FERRETS (MUSTELA NIGRIPES).

Black-footed ferrets (Mustela nigripes) are an endangered species in North America that are highly sensitive to canine distemper virus (CDV) infections and any exposure could be devastating to species recovery. The U.S. Fish and Wildlife Service recovery program has safely used a recombinant DNA (rDNA) canarypox-vectored CDV vaccine, Purevax® Ferret Distemper (PFD), to vaccinate black-footed ferrets. Because of a PFD shortage in 2015, an rDNA vaccine labeled for use in dogs, Recombitek® CDV (rCDV), was chosen to vaccinate black-footed ferrets. Our goal was to compare the serum neutralizing (SN) titers after vaccination of 17 captive and 18 wild black-footed ferrets with rCDV or PFD, respectively, considering ≥1:128 as a protective titer. Both vaccines produced comparable 1 yr postvaccination protective titers in captive and wild black-footed ferrets. In wild black-footed ferrets, one PFD vaccination produced SN titers similar to two PFD vaccinations at 1 yr postvaccination. One year after vaccination with rCDV, SN titers in captive black-footed ferrets were higher than in wild ferrets. These results indicate rCDV may be an effective alternative CDV vaccine in captive black-footed ferrets and PFD should be prioritized for wild ferrets because one dose was effective for animals that can be difficult to recapture.

Determining the effectiveness of using dermal swabs to evaluate the stress physiology of laboratory cephalopods: A preliminary investigation.

To better comprehend the physiology of cephalopods, we used a minimal invasive technique of skin mucus swabs to measure immunoreactive corticosteroids in three cephalopod species commonly kept in captivity and promoted as new model organisms: Euprymna berryi, Sepia bandensis, and Octopus chierchiae. We compared results between sexes and age classes and then evaluated their stress responses during acclimation to a new habitat. To better understand glucocorticoid production, we conducted an adrenocorticotropic hormone, using Cosyntropin (an adrenocorticotropin (ACTH) analogue) challenge with a saline control and swabbed their mantles at 15-minute intervals for 2 h. Results showed cortisol was higher for younger individuals. Additionally, cortisol and corticosterone concentrations decreased by 2-fold after 2 to 4 days of acclimation to a new habitat. We were able to successfully measure 2-fold increase in immunoreactive corticosteroids which reacted with cortisol and corticosterone assays for all the species following ACTH injection, although not all individuals responded similarly. With further investigation, this technique can increase our understanding and management of cephalopods in captivity.

Group structure, but not dominance rank, predicts fecal androgen metabolite concentrations of wild male mountain gorillas (Gorilla beringei beringei).

Androgens are important mediators of male-male competition in many primate species. Male gorillas' morphology is consistent with a reproductive strategy that relies heavily on androgen-dependent traits (e.g., extreme size and muscle mass). Despite possessing characteristics typical of species with an exclusively single-male group structure, multimale groups with strong dominance hierarchies are common in mountain gorillas. Theory predicts that androgens should mediate their dominance hierarchies, and potentially vary with the type of group males live in. We validated the use of a testosterone enzyme immunoassay (T-EIA R156/7, CJ Munro, UC-Davis) for use with mountain gorilla fecal material by (1) examining individual-level androgen responses to competitive events, and (2) isolating assay-specific hormone metabolites via high-performance liquid chromatography. Males had large (2.6- and 6.5-fold), temporary increases in fecal androgen metabolite (FAM) after competitive events, and most captured metabolites were testosterone or 5α-dihydrotestosterone-like androgens. We then examined the relationship between males' dominance ranks, group type, and FAM concentrations. Males in single-male groups had higher FAM concentrations than males in multimale groups, and a small pool of samples from solitary males suggested they may have lower FAM than group-living peers. However, data from two different time periods (n = 1610 samples) indicated there was no clear relationship between rank and FAM concentrations, confirming results from the larger of two prior studies that measured urinary androgens. These findings highlight the need for additional research to clarify the surprising lack of a dominance hierarchy/androgen relationship in mountain gorillas.

Validating the use of fecal glucocorticoid metabolite analysis to assess the adrenocortical activity of the zoo-housed Sichuan takin (Budorcas taxicolor tibetana).

With limited information known about the zoo-housed Sichuan takin (Budorcas taxicolor tibetana), there is a need to gain more knowledge about their basic physiology to be able to better assess their well-being. Our goal was to develop noninvasive methods to evaluate stress physiology in the Sichuan takins housed under human care. The objectives were: (1) validate the use of fecal glucocorticoid metabolite (FGM) analysis to monitor adrenocortical activity and (2) determine the relationship between FGM concentrations and changes in various factors including environmental conditions, reproductive hormones, and social factors. Three (one male and two females) adult Sichuan takins were included in the study from Lincoln Park Zoo. A cortisol enzyme immunoassay was used to analyze FGM from samples that were collected 2-4 times per week. FGM was biochemically validated in the laboratory and biologically validated using pregnancy and parturition. Results showed that 1 day after birth one female had a more than a six-fold increase in FGM. A positive relationship (p < .05) was observed between FGM and temperature for two of the three takins. Finally, FGM values tended to increase during times when aggression (p = .09) and reproductive (p = .08) behaviors were observed. In conclusion, environmental, reproductive, and behavioral factors could affect adrenocortical activity in zoo-housed Sichuan takins; therefore, these methods can be used to assist in the management and conservation of this threatened species both in zoos and potentially in the wild.

Investigation of the utility of feces and hair as non-invasive measures of glucocorticoids in wild black-tailed prairie dogs (Cynomys ludovicianus).

Non-invasive measures of glucocorticoid (GC) hormones and their metabolites, particularly in feces and hair, are gaining popularity as wildlife management tools, but species-specific validations of these tools remain rare. We report the results of a validation on black-tailed prairie dogs (Cynomys ludovicianus), a highly social engineer of the grasslands ecosystem that has experienced recent population declines. We captured adult female prairie dogs and brought them into temporary captivity to conduct an adrenocorticotropic hormone (ACTH) stimulation test, assessing the relationship between plasma GC and fecal glucocorticoid metabolite (FGM) levels following a single injection of a low (4 IU/kg) or high dose (12 IU/kg) of ACTH, compared to a single injection of saline. We also gave repeated injections of ACTH to adult females to assess whether this would result in an increase of hair cortisol concentrations, compared with control individuals repeatedly injected with saline. A single injection of ACTH at either low or high dose peaked plasma cortisol levels after 30 min, and thereafter the cortisol levels declined until 120 min, where they returned to pre-treatment levels comparable to those of the saline injected group. Despite the significant elevation of plasma cortisol in the treatment groups following ACTH injection, the elevation of FGM levels in the treatment groups were not significantly different from those in the control group over the following 12 h. Repeated injection of a high dose of ACTH failed to increase hair cortisol concentration in treatment animals. Instead, hair cortisol levels remained comparable to the pre-treatment mean, despite an increase in post-treatment hair cortisol levels seen in the saline-injected group. The magnitude of increase in the saline control group was comparable to natural seasonal variation seen in unmanipulated individuals. These results highlight that while measurement of GCs and their metabolites in feces and hair are potentially valuable conservation tools for black-tailed prairie dogs, further validation work is required before these matrices can be to real-world conservation applications.

Maternal effects on offspring stress physiology in wild chimpanzees.

Early life experiences are known to influence hypothalamic-pituitary-adrenal (HPA) axis development, which can impact health outcomes through the individual's ability to mount appropriate physiological reactions to stressors. In primates, these early experiences are most often mediated through the mother and can include the physiological environment experienced during gestation. Here, we investigate stress physiology of dependent offspring in wild chimpanzees for the first time and examine whether differences in maternal stress physiology are related to differences in offspring stress physiology. Specifically, we explore the relationship between maternal rank and maternal fecal glucocorticoid metabolite (FGM) concentration during pregnancy and early lactation (first 6 months post-partum) and examine whether differences based on maternal rank are associated with dependent offspring FGM concentrations. We found that low-ranking females exhibited significantly higher FGM concentrations during pregnancy than during the first 6 months of lactation. Furthermore, during pregnancy, low-ranking females experienced significantly higher FGM concentrations than high-ranking females. As for dependent offspring, we found that male offspring of low-ranking mothers experienced stronger decreases in FGM concentrations as they aged compared to males with high-ranking mothers or their dependent female counterparts. Together, these results suggest that maternal rank and FGM concentrations experienced during gestation are related to offspring stress physiology and that this relationship is particularly pronounced in males compared to females. Importantly, this study provides the first evidence for maternal effects on the development of offspring HPA function in wild chimpanzees, which likely relates to subsequent health and fitness outcomes. Am. J. Primatol. 80:e22525, 2018. © 2016 Wiley Periodicals, Inc.

Non-invasive quantification of immunoglobulin A in chimpanzees (Pan troglodytes schweinfurthii) at Gombe National Park, Tanzania.

Immunoglobulin A (IgA) is the primary antibody responsible for mucosal defense in mammals and has been used as a marker for chronic stress and immune status. Therefore, this antibody may provide a more reliable indicator of an individual's immunocompetence than is currently available through other methods. Immunoglobulin A has never before been quantified in a wild population of non-human primates using non-invasive sample collection techniques. In this study, we present methodology for non-invasive IgA extraction in the field and provide quantification of mean fecal IgA concentrations in wild chimpanzees (Pan troglodytes schweinfurthii). During the study period (November 2009-October 2010), we collected fecal samples (N = 1463) from 59 individuals at Gombe National Park, Tanzania. We modified a field extraction technique for steroidal hormones to extract IgA from the fecal samples and then quantified mean IgA concentrations (ng/g) using a commercial human IgA enzyme immunoassay. Mean IgA concentration varied among individuals but not by sex or reproductive status. Mature animals tended toward higher mean IgA concentration than immature. Mean IgA concentration differed by quartile season, following a similar pattern previously observed for respiratory illness rates in this population, with the late dry season having significantly higher averages than the late wet. A circadian rhythm was also evident with mean IgA concentrations higher in samples collected in the latter half of the day. These demographic and temporal patterns of IgA concentration provide baseline values necessary to interpret future results, which may be combined with other health values to better understand the role of health and long-term stress in wild great ape populations. Am. J. Primatol. 80:e22558, 2018. © 2016 Wiley Periodicals, Inc.

Investigation of techniques to measure cortisol and testosterone concentrations in coyote hair.

Long-term noninvasive sampling for endangered or elusive species is particularly difficult due to the challenge of collecting fecal samples before hormone metabolite desiccation, as well as the difficulty in collecting a large enough sample size from all individuals. Hair samples may provide an environmentally stable alternative that provides a long-term assessment of stress and reproductive hormone profiles for captive, zoo, and wild mammals. Here, we extracted and analyzed both cortisol and testosterone in coyote (Canis latrans) hair for the first time. We collected samples from 5-week old coyote pups (six female, six male) housed at the USDA-NWRC Predator Research Facility in Millville, UT. Each individual pup was shaved in six different locations to assess variation in concentrations by body region. We found that pup hair cortisol (F5,57.1 = 0.47, p = 0.80) and testosterone concentrations (F5,60 = 1.03, p = 0.41) did not differ as a function of body region. Male pups generally had higher cortisol concentrations than females (males = 17.71 ± 0.85 ng/g, females = 15.48 ± 0.24 ng/g; F1,57.0 = 5.06, p = 0.028). Comparatively, we did not find any differences between male and female testosterone concentrations (males = 2.86 ± 0.17 ng/g, females = 3.12 ± 0.21 ng/g; F1,60 = 1.42, p = 0.24). These techniques represent an attractive method in describing long-term stress and reproductive profiles of captive, zoo-housed, and wild mammal populations.

Implementing the use of a biobank in the endangered black-footed ferret (Mustela nigripes).

In the current global health climate, many conservation biologists are managing crisis situations, including increased species extinction rates. One strategy for securing wildlife populations into the future is to preserve biomaterials in genome resource banks (GRB; or 'biobanks'). However, for GRBs to be successful we must understand the fundamental reproductive biology of species, along with developing assisted reproductive techniques (ARTs), including AI and semen cryopreservation. ART has been successfully used for several taxa, from amphibians to mammals, including ungulates, carnivores and primates. Not all these success stories implemented the use of a biobank, but one example that discussed herein is the black-footed ferret (Mustela nigripes) GRB. From a founder population of seven individuals, this species has been breeding in a managed setting for nearly 30 years. The goal of the breeding program is to maintain genetic integrity by ensuring each individual has the opportunity to pass his/her genes onto the next generation, while simultaneously providing animals for release into the wild. Scientists have used ART (e.g. AI) in the recovery program. Recently, semen from an individual of the founder population that was cryopreserved for up to 20 years was used successfully for AI, which improved the genetic diversity of the population. The black-footed ferret recovery program can serve as a model for other endangered species and demonstrates the usefulness of ART and GRBs to maintain highly endangered species into the future.

A Road Map for 21st Century Genetic Restoration: Gene Pool Enrichment of the Black-Footed Ferret.

Interspecies somatic cell nuclear transfer (iSCNT) could benefit recovery programs of critically endangered species but must be weighed with the risks of failure. To weigh the risks and benefits, a decision-making process that evaluates progress is needed. Experiments that evaluate the efficiency and efficacy of blastocyst, fetal, and post-parturition development are necessary to determine the success or failure or species-specific iSCNT programs. Here, we use the black-footed ferret (Mustela nigripes) as a case study for evaluating this emerging biomedical technology as a tool for genetic restoration. The black-footed ferret has depleted genetic variation yet genome resource banks contain genetic material of individuals not currently represented in the extant lineage. Thus, genetic restoration of the species is in theory possible and could help reduce the persistent erosion of genetic diversity from drift. Extensive genetic, genomic, and reproductive science tools have previously been developed in black-footed ferrets and would aid in the process of developing an iSCNT protocol for this species. Nonetheless, developing reproductive cloning will require years of experiments and a coordinated effort among recovery partners. The information gained from a well-planned research effort with the goal of genetic restoration via reproductive cloning could establish a 21st century model for evaluating and implementing conservation breeding that would be applicable to other genetically impoverished species.

Effect of Bungee-carcass enrichment on behavior and fecal glucocorticoid metabolites in two species of zoo-housed Felids.

Enrichment can improve animal physiological and psychological well-being. This study sought to promote more natural felid behavior and prevent development or incidence of stereotypies through the use of a feeding enrichment. Our objectives are to use fecal glucocorticoid metabolites values and behavioral observations to quantify the effectiveness of the enrichment device for two species of large cats, Bengal tiger (Panthera tigris tigris; n = 2) and cougar (Felis concolor; n = 2). The feeding enrichment, a white-tailed deer carcass flank securely attached to an AussieDog Products(©) Felid 120-cm bungee, was implemented twice for each individual separated by 1 month. Fecal samples were obtained from each felid and analyzed for pre- and post-enrichment fecal glucocorticoid metabolites (FGM) concentrations using a cortisol enzyme immunoassay. An ethogram with 12 mutual exclusive behavioral categories was utilized to record behavioral responses to the enrichment. Results demonstrate that: 1) there were no differences (P > 0.05) in FGMs for either species between pre- and post-enrichment; 2) pacing decreased (P = 0.025) and walking increased (P = 0.017) after exposure to enrichment in both cougars; and 3) tigers reduced (P = 0.025) 'other' behavioral category after the first enrichment exposure and laid down more (P = 0.025) after the second enrichment exposure. The neutral hormonal impact on the animals coupled with the behavioral changes indicates that this enrichment is successful at altering the animals' behavior without adding physiological stress to their environments. These findings, combined with the low cost and versatility of the enrichment, promote the use of this enrichment to enhance large felid enclosures.

The black-footed ferret: on the brink of recovery?

In an attempt to save the species from extinction, the last remaining 18 black-footed ferrets (Mustela nigripes) were trapped up from the wild to initiate a captive breeding program. Nearly 30 years later more than 8,000 black-footed ferrets have been produced in captivity and approximately 4,100 animals have been reintroduced into 20 sites in eight US states (Arizona, New Mexico, Utah, Colorado, Kansas, Wyoming, South Dakota and Montana), Mexico and Canada. However, full recovery of the species has yet to be achieved, mainly due to limited viable habitat, disease and reduced fecundity. This chapter will highlight the advances in the black-footed ferret recovery program over the last 10 years including: (1) adaptive management techniques employed for the captive population; (2) development of new reintroduction sites and associated challenges facing wild black-footed ferrets; and (3) optimization of assisted reproductive techniques to secure the future of this rare species.

Behavioral and physiological responses in felids to exhibit construction.

Despite the growing body of literature examining the welfare of zoo-housed animals, little standardized work has been published on the effect of construction and environmental disruption on the physiology and behavior of affected animals. When Lincoln Park Zoo (Chicago, IL), embarked on a renovation project for its Kovler Lion House, the opportunity was taken to perform a scientific study of behavioral and physiological markers in the resident felids to determine the effect of construction and environmental disruption. Fecal samples and behavioral observations were collected on four felid species (five individuals) before, during, and after the period of construction. As a group, the average z-score for fecal glucocorticoid metabolite concentration increased during construction relative to baseline. Levels remained elevated after construction, but trended toward baseline. All individuals demonstrated a significant decrease in the frequency of pacing and time spent visible during construction. Overall activity levels also showed a significant decrease relative to baseline measures. As zoological institutions continue to recognize the importance of habitat design, construction and renovation become inevitable. It is important to be aware of the potential consequences this can have on animals in the vicinity and to work toward minimizing negative effects. One recommendation is the availability of ample retreat and hiding space for felids during disruption to their environment.

Using odor cues to elicit a behavioral and hormonal response in zoo-housed African wild dogs.

Olfactory enrichment, like odor cues, can positively affect behavior, reproductive success, and stress physiology in zoo-housed species. Our goal was to determine if odor cues were enriching to the African wild dog (AWD; Lycaon pictus), a species with a complex social structure and a highly developed sense of smell. Our objectives were to: (1) examine changes in activity levels and stress hormone physiology in response to fecal odor cues from natural competitor and natural/unnatural prey species; and (2) determine whether these odor cues could function as effective enrichment for zoo-housed AWDs. Over a 6-month period, fecal samples were collected from two males (AWD 1: dominant, AWD 2: subordinate), fecal glucocorticoid metabolites (FGMs) were validated using an ACTH-challenge, and hormones were analyzed for FGMs by enzyme immunoassay. Behavioral observations were conducted using scan-sampling, and contact and proximity were recorded. AWDs were presented with three fecal odor cues: LION (competitor), CATTLE (unnatural prey), and GAZELLE (natural prey). Only the GAZELLE cue elicited an increase in activity (10.6%) in both individuals and increased positive social behaviors with higher frequencies of affiliative, submissive, and dominant behavior. AWD 1 demonstrated lower (P < 0.05) FGMs than AWD 2 both before and after all odor cues, and FGMs decreased (P = 0.08) in AWD 2 after all cues. We conclude that exposure to natural prey odor cues may be used as effective enrichment for AWDs, and that changes in stress hormone physiology in response to odor cues may be dependent on social rank in this species.

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

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.