Environmental Enrichment Effect on Fecal Glucocorticoid Metabolites and Captive Maned Wolf (Chrysocyon brachyurus) Behavior

Environmental enrichment is a technique that may reduce the stress of nonhuman animals in captivity. Stress may interfere with normal behavioral expression and affect cognitive decision making. Noninvasive hormonal studies can provide important information about the stress statuses of animals. This study evaluated the effectiveness of different environmental enrichment treatments in the diminution of fecal glucocorticoid metabolites (stress indicators) of three captive maned wolves (Chrysocyon brachyurus). Correlations of the fecal glucocorticoid metabolite levels with expressed behaviors were also determined. Results showed that environmental enrichment reduced fecal glucocorticoid metabolite levels. Furthermore, interspecific and foraging enrichment items were most effective in reducing stress in two of the three wolves. No definite pattern was found between behavioral and physiological responses to stress. In conclusion, these behavioral and physiological data showed that maned wolves responded positively from an animal well being perspective to the enrichment items presented.     

Tourist impact on Tibetan macaques

Abstract

Ecotourism is a growing sector of the tourism industry, but few studies to date have quantified its impacts on local people, tourists and wildlife. We present a preliminary study on threat and affiliative behaviors of two groups of free-ranging Tibetan macaques (Macaca thibetana) as a function of habituation and tourist presence. Data indicate that the less habituated group spent less time within sight of tourists compared with the more habituated group. The more habituated group engaged in frequent affiliative behaviors while within sight of humans, whereas affiliative behavior was not observed in the less habituated group. The general pattern of threats consisted of adults primarily threatening juveniles and juveniles primarily threatening humans, possibly due to redirection. No clear pattern of threats as a function of tourist density emerged. Tourist feeding, although discouraged, potentially provided a catalyst for some aggression. Future research will focus on clarifying which human behaviors evoke specific threat responses from monkeys. These data will be used to refine the existing management plan for this monkey population.     

A Comparison of Body Size,Coat Condition and Endoparasite Diversity of Wild Barbary Macaques Exposed to Different Levels of Tourism

Primate tourism is a rapidly growing industry with the potential to provide considerable conservation benefits. However, assessing the impact of tourists on the animals involved is vital to ensure that the conservation value of primate tourism is maximized. In this study, we compared body size, coat condition, and endoparasite diversity of wild, adult Barbary macaques exposed to different levels of tourism. Study animals belonged to three groups located in the Middle Atlas Mountains, Morocco: “green group” (GG) and “scarlet group” (SG) were exposed to negligible/no tourism, while the “tourist group” (TG) was exposed to very high levels of tourism. We used photogrammetry to quantify body size, scored coat condition from photographs, and quantified endoparasite species number from fecal samples. For both males and females, TG animals had deeper stomachs and wider hips than SG and GG animals. The coat condition of TG males was worse than that of SG and GG males, but no difference between groups was seen for females. Fecal samples from TG males contained a greater mean number of protozoan species than did samples from SG and GG males; for females a similar difference was found between TG and GG, but not between TG and SG. This study provides evidence that tourism has impacts on the body size, coat condition, and endoparasite diversity of Barbary macaques at this site. Further study is required to assess whether such effects are detrimental to the health of these animals.     

Determination of Fecal Glucocorticoid Metabolites to Evaluate Stress Response in <Emphasis Type="Italic">Alouatta pigra</Emphasis>

Measuring fecal glucocorticoid metabolites is now a common practice to assess the stress response in primates. Nevertheless, it is important to validate the utilized immunoassay for each primate species before the technique is applied to populations in the wild. We determined the stress response of black howlers (Alouatta pigra) via 2 different group-specific enzyme immunoassays (EIAs). 11-oxoetiocholanolone EIAs are suited to assess the stress response of black howlers via fecal glucocorticoid metabolites. Levels of fecal glucocorticoid metabolites increased after we applied a stressor, i.e. anesthesia, reaching peak concentrations 24–96 h poststressor. Both basal and stress-induced fecal glucocorticoid metabolite levels showed individual variations. The increase of fecal glucocorticoid metabolites after the stressor (paralleling increases in serum) indicates that one can effectively measure adrenocortical activity in Alouatta pigra via these 2 enzyme immunoassays. However, it is important to consider individual variations in the excretion of fecal glucocorticoid metabolites when planning field endocrinological research on Alouatta pigra. Fecal glucocorticoid metabolite excretion takes 1–3 d poststressor depending on the individual. Further, there is an important individual variability in the concentrations of glucocorticoid metabolites, which might reflect differences in stress reactivity or fecal glucocorticoid metabolite metabolism and excretion.     

A non-invasive method for detecting the metabolic stress response in rodents: characterization and disruption of the circadian corticosterone rhythm

Plasma corticosterone (CORT) measures are a common procedure to detect stress responses in rodents. However, the procedure is invasive and can influence CORT levels, making it less than ideal for monitoring CORT circadian rhythms. In the current paper, we examined the applicability of a non-invasive fecal CORT metabolite measure to assess the circadian rhythm. We compared fecal CORT metabolite levels to circulating CORT levels, and analyzed change in the fecal circadian rhythm following an acute stressor (i.e. blood sampling by tail veil catheter). Fecal and blood samples were collected from male adolescent rats and analyzed for CORT metabolites and circulating CORT respectively. Fecal samples were collected hourly for 24 h before and after blood draw. On average, peak fecal CORT metabolite values occurred 7-9 h after the plasma CORT peak and time-matched fecal CORT values were well correlated with plasma CORT. As a result of the rapid blood draw, fecal production and CORT levels were altered the next day. These results indicate fecal CORT metabolite measures can be used to assess conditions that disrupt the circadian CORT rhythm, and provide a method to measure long-term changes in CORT production. This can benefit research that requires long-term glucocorticoid assessment (e.g. stress mechanisms underlying health).     

Relationships among fecal lungworm loads, fecal glucocorticoid metabolites, and lamb recruitment in free-ranging Rocky Mountain bighorn sheep

Most wild Rocky Mountain big-horn sheep (Ovis canadensis canadensis) in northern latitudes are infected with lungworms. Indirect effects of lungworms on bighorn sheep are unknown, but high pulmonary burdens might increase stress (i.e., elevated glucocorticoid levels), and chronic stress could in turn decrease fitness. We hypothesized that high lungworm burdens in Rocky Mountain bighorn ewes increase stress, thereby increasing lamb mortality. To test our hypothesis, one subherd of bighorn sheep in Custer State Park, South Dakota was provided a free-choice loose mineral mix containing the anthelmintic fenbendazole every six weeks from March 1999 to August 2000 to eliminate lungworms; another subherd served as the control. Daily, individually marked ewes were located telemetrically from the ground and uniquely marked animals were observed until they defecated. After the herd moved from the area, fecal samples were collected and stored at -23 C. A consistent number of samples per season per herd (x-=16.56+/-3.99 samples) were collected. Fecal larval lungworm levels (LPG) in the treatment subherd were lower than levels in the control subherd; however, there was no difference in fecal glucocorticoid metabolite (FGM) levels between the two subherds. Fecal glucocorticoid metabolite levels varied by season in both subherds, with levels in winter lower than during the other three seasons. Lamb:ewe ratios were not different between the control and treatment subherds at the end of summer 1999. In contrast, the treatment group had a lower lamb:ewe ratio at the end of summer 2000 despite having lower LPG. However, this result was attributed to lower ewe production, not lower lamb survival. The LPG levels were not correlated with FGM concentrations; instead, FGM levels might reflect normal seasonal patterns. Other factors, including contagious ecthyma, were more important for determining lamb mortality than LPG and FGM levels during our study. We suggest further experimental work over a longer duration to address these relationships.     

Contrasting fecal corticosterone metabolite levels in captive and free-living colonial tuco-tucos (Ctenomys sociabilis)

The environment in which an animal lives can profoundly influence its biology, including physiological responses to external stressors. To examine the effects of environmental conditions on physiological stress reactions in colonial tuco-tucos (Ctenomys sociabilis), we measured glucocorticoid (GC) levels in captive and free-living members of this species of social, subterranean rodent. Analyses of plasma and fecal samples revealed immunoreactive corticosterone (metabolites) to be the most prevalent GC in this species. An adrenocorticotropic hormone challenge confirmed that fecal corticosterone metabolites are responsive to exogenous stressors and provided validation of the commercial enzyme immunoassay kit used to detect these metabolites. Comparisons of adult female C. sociabilis from natural and captive environments revealed significantly higher baseline concentrations of corticosterone metabolites and significantly greater individual variation in metabolite concentrations among free-living animals. These findings suggest that the natural environment in which these animals occur is more challenging and more variable than the captive housing conditions employed. In addition to providing the first evaluation of GC levels in captive and wild colonial tuco-tucos, our findings indicate that the influence of environmental conditions on stress physiology may have important implications for understanding the social behavior of this species in the laboratory and the field.     

Noninvasive monitoring of fecal cortisol metabolites in the eastern chipmunk (Tamias striatus): validation and comparison of two enzyme immunoassays

Monitoring fecal glucocorticoid metabolites in wild animals, using enzyme immunoassays, enables the study of endocrinological patterns relevant to ecology and evolution. While some researchers use antibodies against the parent hormone (which is typically absent from fecal samples), others advocate the use of antibodies designed to detect glucocorticoid metabolites. We validated two assays to monitor fecal cortisol metabolites in the eastern chipmunk (Tamias striatus). We compared an antibody produced against cortisol and one produced against 5α-pregnane-3β, 11β, 21-triol-20-one using a radiometabolism study and an injection with adrenocorticotropic hormone (ACTH). Most cortisol metabolites were excreted in the urine (～83%). Peak excretion in the feces occurred 8 h after injection. Both assays detected an increase in fecal cortisol metabolite levels after injection of ACTH. Males, but not females, exhibited a circadian variation in metabolite levels. The sexes did not exhibit any difference over the time course and route of excretion or the relative increase in fecal cortisol metabolite levels after ACTH injection. The cortisol assay displayed higher reactivity to ACTH injection relative to baseline than did the metabolite assay. While both antibodies gave comparable results, the cortisol antibody was more sensitive to changes in plasma cortisol levels in eastern chipmunks.     

Concentration of fecal cortisol metabolites in chamois in relation to tourist pressure in Tatra National Park (South Poland)

In protected areas, outdoor recreation, and nature-based tourism can act as potential stressors for wildlife. Given the growing demand for nature recreation, the consequences of high tourist visitation on wildlife need to be assessed in order to avoid incompatibilities between public use and species protection goals. The Tatra National Park (Poland), in the Carpathian Mountains, is a unique alpine ecosystem visited by three million tourists per year. It hosts the only native population of an endemic subspecies of chamois (Rupicapra rupicapra tatrica). We investigated the effects of tourist disturbance, the number of visitors, and the season on the concentration of fecal cortisol metabolites (FCM) in Tatra chamois in 2009. FCM levels of chamois were significantly higher and showed higher variation at high tourist disturbance (mean?±?SD, 46.2?±?31.53 ng/g, n?=?56) than at low disturbance sites (mean?±?SD, 17.2?±?8.05 ng/g, n?=?38). Stress levels increased with the number of visitors and therefore showed a peak in summer, coinciding with the highest number of visitation to the national park. A large portion of chamois habitat in Tatra National Park is within the area of influence of the touristic trail network. The temporal or permanent creation of areas free of disturbance in protected areas should be considered, especially in the periods of high tourist visitation. This study highlights the need to monitor the effects of tourist activities on wildlife and to implement new policies in the management of protected areas.     

Interaction between the effects of stress and morphine on body temperature in rats

The relation between stress-induced and morphine-induced body temperature changes was examined in rats. Three groups of eight animals thoroughly habituated to handling and rectal probing, and three groups of eight experimentally naive animals were injected intraperitoneally with either 1, 5, or 30 mg/kg morphine sulphate on each of six consecutive days. Differences in temperature readings from the pre-injection baseline showed that on Day 1 of the experiment stress acted to effectively increase the potency of morphine, causing slightly increased hyperthermia at the lowest dose and greatly increased hypothermia at the highest dose. Thus for habituated animals the dose-response curve for morphine was shifted to the right. By Day 6, after repeated morphine injections, all animals showed a hyperthermic response to morphine and the differences between habituated and unhabituated animals had disappeared. These findings were discussed in terms of the interaction between the temperature changes produced by endogenous opioids in stressed animals and the actions of exogenously administered morphine.     

The Effect of Fission–Fusion Zoo Housing on Hormonal and Behavioral Indicators of Stress in Bornean Orangutans (Pongo pygmaeus)

The welfare of captive animals could be improved if zoos were to place more emphasis on their species-specific needs. In the wild, orangutans live in a fission–fusion social system and have a semisolitary lifestyle. However, most zoos keep orangutans in permanent groups, which may be stressful for them. Apenheul Primate Park in Apeldoorn, Netherlands, houses 14 Bornean orangutans in a simulated fission–fusion social system. To assess how this housing system affects indicators of stress, we measured fecal glucocorticoid metabolites (fGCM) and determined proportions of self-directed behavior (scratching and autogrooming). We compared fGCM concentrations of the Apenheul animals to those of zoo orangutans kept in permanent groups. In addition, we tested the effect of group size, visitor number, sex, age, and change of group composition on fGCM concentrations and proportions of self-directed behavior in the Apenheul orangutans. In contrast to Bornean orangutans housed in permanent groups, we did not find a group size effect on fGCM or on self-directed behavior in Apenheul’s fission–fusion housing system. In addition, fGCM concentrations in Apenheul orangutans increased significantly with visitor numbers. Visitor number also affected proportions of self-directed behavior, and mean proportions of scratching were positively correlated with mean values of fGCM concentrations. Although these results suggest that the fission–fusion housing system in Apenheul reduces the group size effect leading to social stress in Bornean orangutans, they also show that visitors are an important factor that needs to be mitigated if the well-being of captive primates and other zoo animals is to be improved.     

Physiological Stress Response of Captive White-Tailed Deer to Video Collars

ABSTRACT Animal-borne video and environmental data collection systems (AVEDs) are an advanced form of biotelemetry that combines video with other sensors. As a proxy for physiological stress, we assessed fecal glucocorticoid metabolite (FGM) excretion in 7 white-tailed deer (Odocoileus virginianus) fitted with AVED dummy collars; 9 additional deer served as controls. We collected fecal samples over 3 2-week periods: pretreatment, treatment, and posttreatment periods. There were no differences in FGMs across time periods (F_2,218 = 1.94, P = 0.147) and no difference between FGMs of control and treatment individuals (F_1,14 = 0.72, P = 0.411). Fecal glucocorticoid metabolite excretion in AVED-collared deer was indistinguishable from uncollared animals and within the normal, baseline range for this species. Absence of an adrenal response to collaring suggested that AVED collaring does not induce physiological stress in deer.     

Physiological stress levels predict survival probabilities in wild rabbits

Among vertebrates, short-term elevations of glucocorticoid hormones (corticosterone or cortisol) facilitate a suite of physiological and behavioral changes aimed at overcoming environmental perturbations or other stressful events. However, chronically elevated glucocorticoids can have deleterious physiological consequences, and it is still unclear as to what constitutes an adaptive physiological response to long-term stress. In this study, we experimentally exposed European wild rabbits Oryctolagus cuniculus to a source of long-term stress (simulated through a 2- to 4-week period of captivity) and tested whether glucocorticoid physiology predicted two major components of rabbit fitness: body condition and survival probability. Following exposure to long-term stress, moderately elevated serum corticosterone and fecal glucocorticoid metabolites levels in the wild rabbits were negatively associated with body condition, but positively associated with subsequent survival upon release. Our results suggest that the cost of maintaining elevated corticosterone levels in terms of decreased body condition is balanced by the increased chance of survival upon release.     

Stress impairs new but not established relationships in seasonally social voles

Affiliative social relationships are impacted by stressors and can shape responses to stress. However, the effects of stress on social relationships in different contexts are not well understood. Meadow voles provide an opportunity to study these effects on peer relationships outside of a reproductive context. In winter months, female meadow voles cohabit with peers of both sexes, and social huddling is facilitated by exposure to short, winter-like day lengths in the lab. We investigated the role of stress and corticosterone (cort) levels in social behavior in short day-housed female meadow voles. A brief forced swim elevated cort levels, and we assessed the effects of this stressor on new and established relationships between females. In pairs formed following exposure to swim stress, the stressor significantly reduced the fraction of huddling time subjects spent with a familiar partner. Swim stress did not affect partner preferences in pairs established prior to the stressor. Finally, we examined fecal glucocorticoid metabolite levels via immunoassay in voles housed under short day (10 h light) versus long day (14 h light) conditions and detected higher glucocorticoid levels in long day-housed voles. These findings support a role for stress regulation in the formation of social relationships in female meadow voles, and are consistent with a potential role for seasonal variation in cort in the behavioral transition from solitary to social. Together they highlight the importance of stress and possibly glucocorticoid signaling for social behavior.     

Effects of ACTH, capture, and short term confinement on glucocorticoid concentrations in harlequin ducks (Histrionicus histrionicus)

Little is known about baseline concentrations of adrenal hormones and hormonal responses to stress in sea ducks, although significant population declines documented in several species suggest that sea ducks are exposed to increased levels of environmental stress. Such declines have been observed in geographically distinct harlequin duck populations. We performed an adrenocorticotropic hormone (ACTH) challenge to evaluate adrenal function and characterize corticosterone concentrations in captive harlequin ducks and investigated the effects of capture, surgery, and short term confinement on corticosterone concentrations in wild harlequin ducks. Harlequin ducks responded to the ACTH challenge with an average three-fold increase in serum corticosterone concentration approximately 90 min post injection, and a four- to five-fold increase in fecal glucocorticoid concentration 2 to 4 h post injection. Serum corticosterone concentrations in wild harlequin ducks increased within min of capture and elevated levels were found for several hours post capture, indicating that surgery and confinement maintain elevated corticosterone concentrations in this species. Mean corticosterone concentrations in wild harlequin ducks held in temporary captivity were similar to the maximum response levels during the ACTH challenge in captive birds. However, large variation among individuals was observed in responses of wild birds, and we found additional evidence suggesting that corticosterone responses varied between hatch year and after hatch year birds.     

Effects of ACTH, capture, and short term confinement on glucocorticoid concentrations in harlequin ducks (Histrionicus histrionicus).

Little is known about baseline concentrations of adrenal hormones and hormonal responses to stress in sea ducks, although significant population declines documented in several species suggest that sea ducks are exposed to increased levels of environmental stress. Such declines have been observed in geographically distinct harlequin duck populations. We performed an adrenocorticotropic hormone (ACTH) challenge to evaluate adrenal function and characterize corticosterone concentrations in captive harlequin ducks and investigated the effects of capture, surgery, and short term confinement on corticosterone concentrations in wild harlequin ducks. Harlequin ducks responded to the ACTH challenge with an average three-fold increase in serum corticosterone concentration approximately 90 min post injection, and a four- to five-fold increase in fecal glucocorticoid concentration 2 to 4 h post injection. Serum corticosterone concentrations in wild harlequin ducks increased within min of capture and elevated levels were found for several hours post capture, indicating that surgery and confinement maintain elevated corticosterone concentrations in this species. Mean corticosterone concentrations in wild harlequin ducks held in temporary captivity were similar to the maximum response levels during the ACTH challenge in captive birds. However, large variation among individuals was observed in responses of wild birds, and we found additional evidence suggesting that corticosterone responses varied between hatch year and after hatch year birds.     

ECG Response of Koalas to Tourists Proximity: A Preliminary Study

Koalas operate on a tight energy budget and, thus, may not always display behavioral avoidance reaction when placed in a stressful condition. We investigated the physiological response of captive koalas Phascolarctos cinereus in a conservation centre to the presence of tourists walking through their habitat. We compared, using animal-attached data-recorders, the electrocardiogram activity of female koalas in contact with tourists and in a human-free area. One of the koalas in the tourist zone presented elevated heart rate values and variability throughout the recording period. The remaining female in the exhibit area showed a higher field resting heart rates during the daytime than that in the isolated area. In the evening, heart rate profiles changed drastically and both the koalas in the exhibit and in the tourist-free zones displayed similar field resting heart rates, which were lower than those during the day. In parallel, the autonomic nervous systems of these two individuals evolved from sympathetic-dominant during the day to parasympathetic-dominant in the evening. Our results report ECG of free-living koalas for the first time. Although they are preliminary due to the difficulty of having sufficient samples of animals of the same sex and age, our results stress out the importance of studies investigating the physiological reaction of animals to tourists.     

Blubber cortisol qualitatively reflects circulating cortisol concentrations in bottlenose dolphins

Stress hormones, released into circulation as a consequence of disturbance, are classically assayed from blood samples but may also be detected in a variety of matrices. Blubber and fecal samples can be remotely collected from free‐ranging cetaceans without the confounding hormone elevations associated with chase, capture, and handling required to collect blood samples. The relationship between cortisol concentrations in circulation with that of blubber and feces, however, is unknown. To assess these associations, we elevated cortisol by orally administering hydrocortisone for five days in five bottlenose dolphins. Voluntary blood and fecal samples were collected daily; blubber biopsies were collected on day one, just prior to hydrocortisone administration, and days three and five of hydrocortisone administration. We evaluated subsequent changes in several circulating stress hormones as well as cortisol and glucocorticoid metabolites in blubber and feces, respectively. There was a significant association between cortisol levels in serum and in blubber (F_1,12.7 = 14.3, P < 0.01, mR² = 0.57) despite substantial variability in blubber cortisol levels. Counterintuitively, fecal cortisol metabolite levels were inversely related to serum cortisol. The relationship between serum and blubber cortisol levels suggests blubber samples from remote sampling may be useful to detect stress loads in this species.     

Entamoeba histolytica infections in wild and semi-wild orangutans in Sumatra and Kalimantan

Key to the success of orangutan conservation management practices is the prevention of the introduction of infectious diseases to the remaining populations. Previous reports of Entamoeba spp. positive orangutans are of concern as Entamoeba spp. infection has been linked to morbidity and mortality in primates. It remains to be determined if the Entamoeba species infecting orangutans is the pathogenic Entamoeba histolytica. Orangutan fecal samples have been collected from orangutans from sites in Sumatra (Bukit Lawang, Ketambe, and Suaq, 241 samples from 64 individuals), and two sites in Kalimantan (Sebangau and Tuanan, 129 samples from 39 individuals). All samples were from wild orangutans except for a proportion from Sumatra which were from semi-wild (108 samples, 10 individuals). E. histolytica-specific nested PCR assays were carried out on the fecal samples. A total of 36 samples from 17 individuals tested positive for E. histolytica. When compared with published sequences using NCBI BLAST the E. histolytica positive samples showed a 98–99% concordance. The majority (76%, n = 36) of the positive isolates came from semi-wild orangutans in Bukit Lawang. This study supports the growing body of evidence that contact with humans is an important risk factor for infection of wild primates with E. histolytica.     

A validation of extraction methods for noninvasive sampling of glucocorticoids in free-living ground squirrels

Fecal hormone assays provide a powerful tool for noninvasive monitoring of endocrine status in wild animals. In this study we validated a protocol for extracting and measuring glucocorticoids in free-living and captive Belding's ground squirrels (Spermophilus beldingi). We first compared two commonly used extraction protocols to determine which performed better with commercially available antibodies. We next verified the preferred extraction method by correlating circulating and fecal glucocorticoid measures from a group of individuals over time. For this comparison, we used both a cortisol and a corticosterone antibody to determine which had greater affinity to the fecal metabolites. Cortisol was the primary circulating glucocorticoid, but both hormones were present in well above detectable concentrations in the blood, which does not occur in other sciurids. In addition, the cortisol antibody showed greater binding with the fecal extracts than did the corticosterone antibody. Finally, we used adrenocorticotropic hormone and dexamethasone challenges to demonstrate that changes in adrenal functioning are reflected in changing fecal corticoid levels. These results suggest that our extraction protocol provides a fast, reliable assay of stress hormones in free-living ground squirrels without the confounding influence of short-term rises in glucocorticoid concentrations caused by handling and restraint stress and that it can facilitate ecological and evolutionary studies of stress in wild species.