Fecal Glucocorticoid Metabolites Research Articles

Invasive alien species as an environmental stressor and its effects on coping style in a native competitor, the Eurasian red squirrel

Free-living animals cope with environmental stressors through physiological and behavioural responses. According to the unidimensional model, these responses are integrated within a coping style: proactive individuals (bold, active-explorative and social) have a lower hypothalamic–pituitary–adrenal (HPA) axis reactivity than reactive ones (shy, less active-explorative, less social). These associations may change when individuals are exposed to human-induced rapid environmental change (HIREC), such as the introduction of invasive alien species (IAS). Here, we studied Eurasian red squirrels to investigate the relationship between personality traits and one integrated measure of HPA axis activity, both in areas uncolonized (natural populations) and colonized by an IAS, the Eastern grey squirrel (invaded populations). We expected an association between physiological and behavioural responses, and that activity, exploration and social tendency would covary, forming a behavioural syndrome in natural populations, while competition with the IAS was predicted to disrupt these associations. We used faecal glucocorticoid metabolites (FGMs) as an integrated measure of adrenocortical activity, and measured the levels of four personality traits (exploration, activity, activity-exploration and social tendency) with an open field test and a mirror image stimulation test. We found no correlation between FGMs and personality traits, neither in natural nor invaded populations. However, we found correlations among personality traits in areas without interspecific competition, indicating a behavioural syndrome, which was disrupted in invaded populations. This is one of the few studies showing that an IAS, acting as an environmental stressor, alters a native species' behavioural syndrome, but does not influence its coping style.

Simultaneous investigation of urinary and faecal glucocorticoid metabolite concentrations reveals short- versus long-term drivers of HPA-axis activity in a wild primate (Papio ursinus)

Glucocorticoids (GCs), a class of steroid hormones released through activation of the hypothalamic–pituitary–adrenal (HPA) axis, perform many vital functions essential for survival, including orchestrating an organism’s response to stressors by modulating physiological and behavioural responses. Assessing changes and variation in GC metabolites from faecal or urine samples allows for the non-invasive monitoring of HPA-axis activity across vertebrates. The time lag of hormone excretion differs between these sample matrices, which has implications for their suitability for studying effects of different temporal nature on HPA-axis activity. However, simultaneous comparisons of predictors of faecal and urinary GC metabolites (fGCs and uGCs, respectively) are lacking. To address this gap, we employ frequent non-invasive sampling to investigate correlates of fGCs and uGCs in wild chacma baboons (Papio ursinus) (n = 17), including long-term (dominance rank, season, female reproductive state) and short-term (time of day, daily weather conditions) factors. Correlated with increasing day length, fGCs gradually decreased from winter to summer. No seasonal effect on uGCs was found but ‘rain days’ were associated with increased uGCs. Pregnant females had significantly higher fGCs compared to cycling and lactating females, whereas uGCs were not statistically different across reproductive states. A circadian effect was observed in uGCs but not in fGCs. Dominance rank did not affect either fGCs or uGCs. Our study highlights the difference in inherent fluctuation between uGCs and fGCs and its potential consequences for HPA-axis activity monitoring. While uGCs offer the opportunity to study short-term effects, they undergo more pronounced fluctuations, reducing their ability to capture long-term effects. Given the increasing use of urine for biological monitoring, knowledge of this potential limitation is crucial. Where possible, uGCs and fGCs should be monitored in tandem to obtain a comprehensive understanding of short- and long-term drivers of HPA-axis activity.

Integrating the female masculinization and challenge hypotheses: Female dominance, male deference, and seasonal hormone fluctuations in adult blue-eyed black lemurs (Eulemur flavifrons)

In the decades since female social dominance was first described in strepsirrhine primates, researchers have sought to uncover the proximate and ultimate explanations for its development. In the females of various female-dominant species, androgens have been implicated as regulators of behavior and/or predictors of seasonal fluctuations in aggression (the ‘Female Masculinization Hypothesis’). Males, more generally, respond to changing social demands via seasonal fluctuations in androgen-mediated behavior (the ‘Challenge Hypothesis’), that may also entail changes in activation of the hypothalamic-pituitary-adrenal axis. Here, we explore if androgens, glucocorticoids, and intersexual behavior fluctuate seasonally in the female-dominant, blue-eyed black lemur (Eulemur flavifrons), with potential consequences for understanding female aggression and male deference. Across two studies conducted during the breeding and nonbreeding seasons, we assessed rates of mixed-sex, dyadic social behavior (aggression and affiliation) and concentrations of fecal glucocorticoid metabolites (Study 1) and serum sex hormones (androstenedione, testosterone, and estradiol; Study 2). Our results align with several predictions inspired by the Female Masculinization and Challenge Hypotheses for intersexual relations: During the breeding season, specifically, both aggression and androstenedione peaked in females, while female-initiated affiliation decreased, potentially to facilitate female resource access and reproductive control. By comparison, all target hormones (androgens, estrogen, and glucocorticoids) peaked in males, with glucocorticoid concentrations potentially increasing in response to the surge in female aggression, and unusually high estrogen concentrations year-round potentially facilitating male deference via male-initiated affiliation. These results suggest complex, seasonally and hormonally mediated behavior in Eulemur flavifrons.

Physical and behavioral indicators associated with hormonal changes during musth in zoo-housed and free-ranging Asian elephants (Elephas maximus)

In-situ and ex-situ Asian elephant populations are threatened with extinction, and male elephants pose unique challenges to long-term sustainability. The heightened sexual state of “musth” is accompanied by a suite of physical, behavioral and physiological changes. Furthermore, musth is unique to male elephants and requires special consideration when developing short- and long-term management strategies for elephants in the wild and in human care. The purpose of this study was to identify associations between fecal hormone metabolites [fecal androgen metabolites, FAM; fecal glucocorticoid metabolites, FGM; and fecal triiodothyronine (T3) metabolites, FT3] and visible musth indicators [temporal gland secretions (TGS) and urine dribbling (UD)], and behavioral changes around musth. From fecal samples collected non-invasively from wild elephants in Wasgamuwa National Park, Sri Lanka, and zoo-housed elephants in the United States, we hypothesized that (1) TGS and/or UD would be associated with changes in FAM, FGM, and/or FT3 concentrations; (2) variation in fecal hormone metabolites would be associated with increased locomotion and chemosensory behavior, and decreased foraging; and (3) relationships we identified would be similar between wild and zoo-housed elephants. We found that FAM concentrations changed significantly with TGS and UD activity in both wild and zoo elephants. Further while FGM concentrations were higher with increased TGS and UD in zoo elephants, the opposite pattern occurred in wild elephants. We did not identify substantial change in FT3 concentrations with TGS/UD activity. Behavioral changes in zoo elephants were significantly associated with FAM concentration as predicted, but these relationships were more difficult to identify in wild elephants due to lower sample availability. Further, FGM concentration was directly related to time spent locomoting in zoo elephants, but no other apparent association existed between FGM concentration with other behaviors in zoo elephants, or in any behaviors in wild elephants. Likewise, we did not report associations between FT3 and any behaviors we measured. This study contributes to our understanding of the complex response patterns that male Asian elephants exhibit around musth, and it provides another example of complementary in-situ–ex-situ research that can be directly applied to improve the well-being of elephants and other wildlife.

Exploring seasonal variation in the faecal glucocorticoid concentrations of African elephants (

Context The wide-ranging movement of African elephants (Loxodonta africana) is largely driven by the spatio-temporal distribution of water and forage, and often leads to their travelling outside of formally protected areas. With an increase in drier periods predicted across Africa due to climate change, it is critically important to understand how elephants physiologically respond to alterations in the availability and distribution of resources. Aims We assessed variation in the adrenal activity of elephants living in Kenya’s Tsavo East National Park between wet and dry seasons, as well as among individuals found in Tsavo East National Park and privately protected Rukinga Wildlife Sanctuary (part of the Kasigau REDD+ wildlife corridor) in the dry season, when the area experiences an influx of elephants in search of alternative resources. Methods We opportunistically collected fresh elephant faecal samples across the two seasons and locations for analysis of faecal glucocorticoid metabolite (fGCM, a proxy for stress) and nitrogen (Nf, an indirect measure of diet quality) concentrations. The Normalised Difference Vegetation Index (NDVI) was employed as an additional indicator of habitat quality. Key results In Tsavo East N.P. Nf and NDVI were both significantly lower during the dry season, indicating poorer habitat quality compared with the wet season. Although elephant fGCM concentrations tended to be higher in the dry season than the wet, the differences were not significant. There was no difference between elephant fGCMs measured in Tsavo East N.P. and Rukinga W.S. during the dry season, nor in habitat quality between the two locations. Conclusions Elephants living in Tsavo may be physiologically unaffected by (or adapt to) typical seasonal changes in habitat quality that could lead to nutritional stress; however, whether this is the case during extended periods of severe drought requires further investigation. Rukinga W.S. provides a safe haven of sufficient habitat quality for elephants searching for alternative resources during this period. Implications Extended dry periods are likely to become increasingly common in semiarid savannahs, and implications for wildlife must be closely monitored. Privately protected land outside formally protected areas plays an important role in conservation efforts, which should be considered when making land management plans.

Loss of an apex predator in the wild induces physiological and behavioural changes in prey.

Predators can impact prey via predation or risk effects, which can initiate trophic cascades. Given widespread population declines of apex predators, understanding and predicting the associated ecological consequences is a priority. When predation risk is relatively unpredictable or uncontrollable by prey, the loss of predators is hypothesized to release prey from stress; however, there are few tests of this hypothesis in the wild. A well-studied predator-prey system between white sharks (Carcharodon carcharias) and Cape fur seals (Arctocephalus pusillus pusillus) in False Bay, South Africa, has previously demonstrated elevated faecal glucocorticoid metabolite concentrations (fGCMs) in seals exposed to high levels of predation risk from white sharks. A recent decline and disappearance of white sharks from the system has coincided with a pronounced decrease in seal fGCM concentrations. Seals have concurrently been rafting further from shore and over deeper water, a behaviour that would have previously rendered them vulnerable to attack. These results show rapid physiological and behavioural responses by seals to release from predation stress. To our knowledge, this represents the first demonstration in the wild of physiological changes in prey from predator decline, and such responses are likely to increase given the scale and pace of apex predator declines globally.

Cascading Effects of Hunting Disturbance on Northern Bobwhite Behavior, Physiology, and Survival

The northern bobwhite (Colinus virginianus; hereafter, bobwhite) is an important gamebird across the United States and has been in decline for several decades. As a commonly hunted prey species, the bobwhite provides an ideal study species to investigate the use of proactive and reactive antipredator behaviors in response to hunting pressure. We designed an experiment to understand how late-season hunting affects bobwhite demographics using fecal glucocorticoid (fGCM) concentrations, foraging and movement behaviors, survival, and breeding season metrics. Our results show that bobwhite responded to increased interactions with a shotgun through proactive responses. After one encounter with a discharged shotgun, bobwhite began foraging farther from supplemental feed where the risk of encountering a hunting party was the greatest (β = 0.21, 95% Bayesian credible interval [CrI]: 0.06–0.36). Bobwhite responded to increased hunting pressure, particularly late-season hunting pressure, via reactive responses through increased fecal glucocorticoid metabolite (fGCM) concentrations (β = 2.18, 95% CrI: 0.21–4.15), resulting in decreased survivorship in non-harvested individuals (β = -0.42, 95% CrI: -0.77 to -0.07) and decreased fecundity (β = -0.17, 95% CI: -0.31–0.09). These results can help inform hunting season regulations and management decisions aiding in bobwhite recovery.

Physiological acclimation of elk during population restoration in the Missouri Ozarks, USA.

Conservation translocations—the intentional movement of animals to restore populations—have increased over the past 30 years to halt and reverse species declines and losses. However, there are many challenges translocated animals face that should be considered for restoration programs to be successful. Understanding how long it takes for translocated animals to acclimate to these challenges and their new landscape is a critical component of post-release population management. Physiological measures such as hormone responses are increasingly used to assess animal responses and acclimation to disturbances including translocation. We determined the physiological acclimation period of elk (Cervus canadensis) translocated to the Missouri Ozarks, USA, as part of a restoration effort. From 2011 to 2013, we translocated 108 GPS-radio-collared elk from Kentucky, USA, to Missouri, USA, and collected faecal samples for glucocorticoid metabolite extraction to use as an indicator of physiological acclimation. We modelled the response of population-wide faecal glucocorticoid metabolites (fGCMs) across the initial 9 years of the restoration in response to days following release and additional site-specific covariates. Presence of white-tailed deer (Odocoileus virginianus) hunts and monthly precipitation levels were positively and negatively associated with fGCM levels, respectively. Concurrent with influences from site-specific conditions on the release landscape, fGCM levels declined following release. We identified a breakpoint in fGCM decline at ~42 days following translocation releases suggesting elk acclimated physiologically relatively quickly compared to other species. The fast physiological acclimation by Missouri elk suggests effective use of temporary post-release management efforts. Determining how quickly animals acclimate following translocations allows researchers to tailor post-release management plans to each species’ needs, thus maximizing the success of future translocation efforts while minimizing costs.

A field-friendly alternative to freeze-drying faeces for glucocorticoid metabolite analyses of African wild dogs (Lycaon pictus)

Endocrine studies using faeces as hormone matrix have become increasingly popular to examine adrenocortical activity in wildlife. A prerequisite for this approach is to minimize alteration of faecal glucocorticoid metabolite (fGCM) composition post-defecation. This is done by freezing the collected material as soon as possible after collection, and removing moisture from the frozen faecal samples afterwards (usually by freeze-drying). In remote areas, freeze-drying opportunities are often limited, and in the case of the African wild dog (Lycaon pictus), established assays revealed that fGCM concentrations remain comparable for only ∼24h post-defaecation. In the present study, three cost-effective drying treatments (exposure to sunlight, placement in a solar oven, and use of a food dehydrator) were investigated as alternatives to the golden standard of freeze-drying faeces.•In comparison to freeze-dried material, African wild dog faecal samples dried through sunlight exposure, a solar oven, and use of a food dehydrator revealed no significant differences in respective fGCM concentrations measured.•A food dehydrator would be the preferable option to dry African wild dog faeces if limited electrical supply is available. This technique dries faeces the fastest, and negates any reliance on weather conditions.

Spatial constraints and seasonal conditions but not poaching pressure are linked with elevated faecal glucocorticoid metabolite concentrations in white rhino

Context Due to considerable declines in African wildlife populations, most large African mammals are managed inside protected areas. Protected areas come in various sizes, and have different environmental features, climates and management strategies (i.e. ‘hands-on’ or ‘hands-off’) that can influence an animals’ homeostasis. White rhinos (Ceratotherium simum simum) are found almost exclusively within protected areas where population sizes are driven by natural factors and poaching pressures. Aims Our aim was to understand the effect of natural and anthropogenic factors on the adrenocortical response of white rhinos within three protected areas. Specifically, we wanted to understand how poaching pressure, protected area size (<500 km2), season (wet and dry) and rainfall patterns were responsible for driving adrenocortical activity in white rhino. Methods To understand the relationship between rhino adrenocortical responses and different environmental and anthropogenic stressors, we quantified glucocorticoid metabolites in faecal samples (fGCM) collected from four populations within three protected areas (i.e. two small parks, one big park) during the wet and dry seasons. Key results We found differences in seasonal fGCM concentrations, with a 42% increase during the dry season, and no differences in fGCM concentrations between the high and low poaching areas. Additionally, we found fGCM concentrations in samples from the small parks were respectively 38% and 42% higher than in samples from the large park during both the dry and wet seasons compared. Conclusions Our results suggest that white rhinos may experience physiological stress in smaller parks, especially during the dry season when resources are limited. Implications By mitigating stress associated with reduced access to resources and spatial constraints, managers may better promote the viability of large mammals in small protected areas.

Non-Invasive Assessment of the Seasonal Stress Response to Veterinary Procedures and Transportation of Zoo-Housed Lesser Anteater (Tamandua tetradactyla).

Simple SummaryWild mammals under human care are routinely exposed to management procedures that could be stressful and affect their welfare. Besides, wild animals in captivity are frequently housed under natural climatic conditions, which could also be a year-round challenge that affects how they cope with human intervention. Therefore, stress responses to seasons and management procedures of zoo-housed lesser anteaters (Tamandua tetradactyla) were non-invasively monitored. Behavioural and physiological stress responses differed between seasons. Then, lesser anteaters were studied during winter and summer by exposing them to a routine veterinary check and transportation. Behaviour before and after the procedures was video-recorded and analysed for possible alterations of activity. Faecal glucocorticoid metabolites were measured to evaluate adrenocortical activity. Both procedures altered only behavioural activities, and the response was stronger in summer than winter. We conclude that routine procedures may only slightly compromise the welfare of zoo-housed lesser anteaters, affecting them less in winter than in summer.Management procedures affect behavioural and physiological stress responses of wild mammals under human care. According to the Reactive Scope Model, normal values are presumed to exist within predictive and reactive ranges. First, stress parameters of zoo-housed adult Tamandua tetradactyla were evaluated in winter and summer (29 days each), determining the level of behaviour and/or physiological parameters needed to respond to predictable environmental changes. Secondly, the effects of veterinary procedures and transportation were studied in both seasons. Non-invasive methods were applied, assessing behaviour through videos and adrenocortical activity by faecal glucocorticoid metabolites (FGMs). Lesser anteaters exhibited seasonality (summer > winter) in some behavioural parameters, such as nocturnal activities, as well as in the activity cycle (e.g., acrophase) and FGMs. A veterinary check elicited an increase in total activity (TA), natural behaviours and repetitive locomotion and affected the activity cycle, particularly in summer. Transport produced changes in TA, nocturnal and natural activity and some variables of the activity cycle, mostly during summer. Although the effects of routine management procedures were different from each other and presumably stressful, they elicited changes only at the behavioural level, which was greater during summer. The differences observed according to non-invasive methodologies highlight the importance of a multidisciplinary approach in this context and suggest that it is unlikely that individual welfare was affected.

Quantification of faecal glucocorticoid metabolites as a measure of stress in the rock hyrax Procavia capensis living in an urban green space

Despite the abundance of rock hyrax Procavia capensis within South Africa's urban areas, there is not much information available about the effect of anthropogenic activities on rock hyrax wellbeing. To determine the potential impact of anthropogenic disturbance on adrenocortical activity, we conducted an ACTH challenge to identify a suitable enzyme‐immunoassay (EIA) for measuring faecal glucocorticoid metabolite (fGCM) concentrations in the rock hyrax. This study identified an 11β‐hydroxyaetiocholanolone EIA as the most suitable assay in this regard. The fGCM levels measured, indicate the physiological stress response in different rock hyrax populations, living in an area with varying degrees of anthropogenic activity (low, medium, high) within the National Botanical Garden of Pretoria, South Africa. The species' habituation to human numbers (weekly mean number of people) was examined by determining individual flight initiation distance (FID). Seasonally, there were overall higher fGCM concentrations in late spring compared to winter. The fGCM concentrations, although not significantly different but possibly biologically relevant, in the section with the lowest anthropogenic disturbance were ~10% higher compared to those in the section with medium disturbance, and ~20% higher compared to those in the section with the highest disturbance. Animal FID did not differ significantly between seasons but they did differ significantly between sections, and decreased in accordance with fGCM concentrations. The non‐invasive approach established in this study provides a foundation for assessing rock hyrax wellbeing, and can help better understand how anthropogenic presence is perceived as a stressor in this species.

Applying Behavioral and Physiological Measures to Assess the Relative Impact of the Prolonged COVID-19 Pandemic Closure on Two Mammal Species at the Oregon Zoo: Cheetah (A. jubatus) and Giraffe (G. c. reticulata and G. c. tippelskirchii).

Simple SummaryDuring the COVID-19 global pandemic the Oregon Zoo closed to all visitors and non-essential staff from 15 March 2020 to 12 July 2020. This presented a unique opportunity to conduct a study on the behavioral and physiological changes associated with the transitions between visitor presence and visitor absence on some of our more sensitive species. Using behavioral scan-sampling and fecal hormone monitoring of fecal glucocorticoid metabolites (fGM), two cheetahs and two giraffes were observed through two transition periods: the initial closure of the Oregon Zoo in March 2020 and the subsequent reopening in July 2020. We found significant increases in fGM concentrations for both cheetahs and giraffes between the two transition periods, but not within each specific transition. We also found some differences in behavior frequencies for both cheetahs and giraffes. For the cheetahs, ‘not visible’ significantly increased within the second transition period, resulting in their being less visible to visitors, and the cheetahs also spent less time showing locomotion behavior after the Zoo reopened. The giraffes, in turn, expressed significant differences in vigilant behaviors, with increased vigilance shown while fewer visitors were around. This study illustrates the complexity of investigating the visitor effect in different species and the individualistic nature of the responses of both the cheetahs and giraffes at the Oregon Zoo. Overall, however the observed changes in fGM concentrations and behavioral expressions were relatively minor and may have been more strongly related to social changes (giraffe) and medical events (cheetah) than to visitor activity and the Zoo’s opening status.The effect of visitor presence on zoo animals has been explored in numerous studies over the past two decades. However, the opportunities for observations without visitors have been very limited at most institutions. In 2020, the Oregon Zoo was closed, in response to the global SARS-CoV-2 (COVID-19) pandemic, from 15 March 2020 to 12 July 2020, resulting in approximately four consecutive months without visitor presence. This study aimed to quantify potential behavioral and hormonal changes expressed during two transition periods in zoo visitor attendance: the initial time period before and after closure in March 2020 and time before and after reopening in July 2020. Fecal glucocorticoid metabolite (fGM) concentrations of resident giraffes (n = 2) and cheetahs (n = 2) were tracked using enzyme immunoassay (EIA) analyses. Average fGM concentrations during the two transition periods were compared using a two-way mixed ANOVA. Additionally, twice-weekly scan sampling was used to quantify behavioral observations across the transitions, which were analyzed as individual behavior proportions. Individual behavior proportions were compared across the Zoo’s opening status and time of day using Kruskal–Wallis (H) tests. The results of our analyses showed the following outcomes: (1) significant increases in fGM concentrations for cheetahs and giraffes between the transition periods but not within them; (2) a significant increase in time spent ‘not visible’ in the cheetahs in the second transition period; and (3) increased vigilance behaviors in the giraffes immediately after the Zoo’s closure. However, the changes observed in fGM concentrations may be more strongly correlated with concomitant social changes (giraffes) and some medical events (cheetahs) rather than with the Zoo’s opening status. Nevertheless, this study was able to quantify differences in behavioral frequencies and fGM concentration in cheetahs and giraffes at the Oregon Zoo during the times of transition between visitor’s presence and absence. The results indicate that, while there was a possible, but relatively minor impact of the presence and absence of visitors on some behaviors, the differences observed in fGM concentration may have been more affected by some of the concomitant social changes and medical events that happened during the same period than by the presence or absence of visitors.

Clinical health issues, reproductive hormones, and metabolic hormones associated with gut microbiome structure in African and Asian elephants

BackgroundThe gut microbiome is important to immune health, metabolism, and hormone regulation. Understanding host–microbiome relationships in captive animals may lead to mediating long term health issues common in captive animals. For instance, zoo managed African elephants (Loxodonta africana) and Asian elephants (Elephas maximus) experience low reproductive rates, high body condition, and gastrointestinal (GI) issues. We leveraged an extensive collection of fecal samples and health records from the Elephant Welfare Study conducted across North American zoos in 2012 to examine the link between gut microbiota and clinical health issues, reproductive hormones, and metabolic hormones in captive elephants. We quantified gut microbiomes of 69 African and 48 Asian elephants from across 50 zoos using Illumina sequencing of the 16S rRNA bacterial gene.ResultsElephant species differed in microbiome structure, with African elephants having lower bacterial richness and dissimilar bacterial composition from Asian elephants. In both species, bacterial composition was strongly influenced by zoo facility. Bacterial richness was lower in African elephants with recent GI issues, and richness was positively correlated with metabolic hormone total triiodothyronine (total T3) in Asian elephants. We found species-specific associations between gut microbiome composition and hormones: Asian elephant gut microbiome composition was linked to total T3 and free thyroxine (free T4), while fecal glucocorticoid metabolites (FGM) were linked to African elephant gut microbiome composition. We identified many relationships between bacterial relative abundances and hormone concentrations, including Prevotella spp., Treponema spp., and Akkermansia spp.ConclusionsWe present a comprehensive assessment of relationships between the gut microbiome, host species, environment, clinical health issues, and the endocrine system in captive elephants. Our results highlight the combined significance of host species-specific regulation and environmental effects on the gut microbiome between two elephant species and across 50 zoo facilities. We provide evidence of clinical health issues, reproductive hormones, and metabolic hormones associated with the gut microbiome structure of captive elephants. Our findings establish the groundwork for future studies to investigate bacterial function or develop tools (e.g., prebiotics, probiotics, dietary manipulations) suitable for conservation and zoo management.

Seasonal Variation in Fecal Glucocorticoid Levels and Their Relationship to Reproductive Success in Captive Populations of an Endangered Parrot

Many species are threatened with extinction, and captive breeding programs are becoming more common to avoid this outcome. These programs serve to prevent extinction and produce individuals for eventual reintroduction to natural populations in historical habitat. Captive animals experience different energetic demands than those in the wild, however, and as a result may have different levels of glucocorticoid hormones. Glucocorticoids help with responses to energetically expensive and potentially stressful situations. Elevated glucocorticoid levels can also potentially alter reproduction and other key behaviors, thus complicating successful captive breeding. The Puerto Rican parrot (Amazona vittata) is a critically endangered parrot that currently exists in only two wild and two captive populations. Its recovery program provides a good platform to better understand how glucocorticoid levels may relate to reproductive success under captive conditions. We validated a corticosterone assay in this species and used non-invasive techniques of measuring fecal glucocorticoid metabolites of males and females from two captive populations (Rio Abajo and El Yunque) of Puerto Rican parrots over two consecutive breeding seasons, 2017 and 2018, and the pre-breeding season of 2018, which occurred just after Hurricane Maria struck Puerto Rico. Our results show that levels of fecal glucocorticoid metabolites of males measured during the breeding season of 2018 negatively correlated to the number of total eggs and fertile eggs laid by pairs. In contrast, there was a positive relationship of female fecal glucocorticoid metabolite levels during the pre-breeding season of 2018 with total eggs laid. In males from the Rio Abajo population, we found seasonal differences in fecal glucocorticoid metabolite levels, with higher levels during the pre-breeding season of 2018 compared to both 2017 and 2018 breeding seasons. There was no difference in the mean value of male fecal glucocorticoid metabolites between the 2017 breeding season and 2018 breeding season which started four months after Hurricane Maria struck Puerto Rico. We did find sex differences during the pre-breeding season of 2018 in birds from the Rio Abajo population. Adjustments in the care routine of both populations that could reduce circulating baseline glucocorticoids and avoid frequent, sudden elevations of glucocorticoids should be considered. These results provide a baseline for future comparison with reintroduced populations of this endangered species and other species with captive breeding programs.

Potential endocrine correlation with exposure to domoic acid in Southern Right Whale (Eubalaena australis) at the Península Valdés breeding ground.

In waters off Península Valdés (PV), Argentina, southern right whales (SRW, Eubalaena australis) are occasionally exposed to domoic acid (DA), a neurotoxin produced by diatoms of the genus Pseudo-nitzschia. Domoic acid toxicity in marine mammals can cause gastrointestinal and neurological clinical signs, alterations in hematologic and endocrine variables, and can be fatal in extreme cases. In this study, we validated an enzyme immunoassay to quantify fecal glucocorticoid metabolites (fGCm) in 16 SRW fecal samples from live and dead stranded whales in PV from 2013 to 2018 and assessed fGCm levels associated with DA exposure. Overall, fGCm levels were significantly lower in SRWs with detectable fecal DA (n = 3) as compared to SRWs with undetectable fecal DA levels (n = 13). The highest fecal DA was observed in a live lactating female, which had low fGCm compared to the other lactating females studied. The highest fGCm was observed in a lactating female with undetectable DA; interestingly, at the time of sample collection, this female was sighted with two calves, an extremely unusual occurrence in this species. Though the sample size of these exceptionally rare breeding-season fecal samples was unavoidably small, our study provides evidence of potential adrenal alterations in whales exposed to an environmental neurotoxin such as DA.

How is Western Lowland Gorilla (Gorilla gorilla gorilla) Behavior and Physiology Impacted by 360 Degree Visitor Viewing Access?

The effect visitors may have on the welfare of professionally managed animals is vital to consider. The present study utilized an experimental approach to examine how 360° visitor viewing access (i.e., viewing from all sides of the habitat) impacts the behavior and physiology of Western lowland gorillas (Gorilla gorilla gorilla, N = 7). Data collection included behavioral observations and obtaining fecal samples to examine physiological indicators of welfare. The study included a baseline period observing the gorillas’ behavior and physiology during the typical 360° visitor viewing access and a treatment period examining the same indicators but reducing viewing access by approximately 70%. Behavioral states, behavioral events, and hormone data were compared across conditions using Wilcoxon signed-rank tests. Restricted viewing did not impact social or solitary grooming (as a state behavior), social or solitary play, foraging, stereotypies, locomotion, inactivity, or behavioral diversity. However, restricted viewing significantly reduced solitary grooming events, fecal glucocorticoid metabolites, and the ratio of glucocorticoid metabolites to dehydroepiandrosterone metabolites. These results suggest that 360° visitor viewing access may have an impact on the welfare of gorillas. However, further research is necessary to thoroughly understand the influence of allowing 360° visitor viewing on behavior and its possible interaction with variables of the zoo environment.

Behavioural diversity as a potential welfare indicator for professionally managed chimpanzees (Pan troglodytes): Exploring variations in calculating diversity using species-specific behaviours

AbstractBehavioural diversity may serve as a positive indicator of animal welfare that can be applied in long-term monitoring schemes in managed settings (eg zoos, laboratories, farms). Behavioural diversity is often higher when animals live in stimulating environments and experience positive events. Unfortunately, welfare researchers have not adopted consistent, standardised approaches to measuring behavioural diversity. The goal of this exploratory study was to utilise data from 41 adult chimpanzees (Pan troglodytes) housed across 16 zoological institutions to examine various models of Shannon's Diversity Index. Specifically, we investigated the impact of: combining versus splitting behaviours, including only positive behaviours, including human interaction, and considering recipient behaviours. We evaluate how the inclusion or exclusion of different behaviours impacts the relationship of behavioural diversity with: (i) concentrations of faecal glucocorticoid metabolites (GCM), a common indicator of adrenal activity; (ii) concentrations of immunoglobulin-A (IgA), an indicator of immune function and potential indicator of positive welfare; and (iii) stereotypic behaviour, a validated indicator of poor welfare. Most indices had significant negative relationships with faecal GCM. Animals that express a variety of behaviours from their species-typical repertoire have lower average faecal GCM concentrations and are likely experiencing better welfare. We did not find significant relationships between the behavioural diversity indices and IgA concentrations. Two indices were inversely associated with stereotypic behaviour. Our findings provide additional support for using Shannon's Diversity Index to calculate behavioural diversity as a robust, valid measure of positive welfare. However, future publications must justify the process for including or excluding behaviours from calculations.

How do humans impact yellow-bellied marmots? An integrative analysis

While many studies document specific human impacts on the behaviour and physiological responses of wildlife to humans, most have focused on these responses independently and over relatively short periods of time. To address this, we studied a suite of responses in yellow-bellied marmots (Marmota flaviventer) in two distinct years, 9 years apart. We first quantified the rate that vehicles, pedestrians, and bicycles passed marmot colonies, focusing on two years (2009 and 2018) to determine how, if any of these relationships changed over time. We then asked whether these disturbances were associated with marmot physiological responses including neutrophil-lymphocyte ratios (NLR), and faecal glucocorticoid metabolites levels (FGM), as well as behavioural responses including flight initiation distance (FID) and the time marmots allocated to foraging, and finally a key fitness correlate—the rate of mass gain. We found that the number of vehicles and pedestrians passing within 300 m of a marmot colony stayed relatively constant between years, while there was variation in bicycles passing by marmot colonies. Despite similar length in growing seasons, marmots at colonies that had higher disturbance gained mass more rapidly in 2018 than in 2009. By examining a suite of physiological, behavioural, and key fitness correlates, and how they changed, our findings are consistent with the hypothesis that marmots became more tolerant of human disturbances over time. This provides promise for this population in dealing with inevitable increases in eco- and nature-based tourism.

Glucocorticoid Production, Activity Levels, And Personality Traits Of Fennec Foxes (Vulpes zerda) Managed For Different Roles In Zoos

ABSTRACT Fecal glucocorticoid metabolite (FGM) concentrations, activity, and personality were assessed for 35 fennec foxes (Vulpes zerda) to determine whether animals managed as ambassadors differed from exhibit or off-exhibit animals. A FGM assay, pedometer, and personality assessment tool were validated. Then, fecal samples and movement data were collected during winter and summer periods. Handling was recorded, and the personality of each fox was evaluated. Generalized linear mixed models assessed the relationships between FGM concentrations, activity, personality, handling, sex, season, rearing type, and role. FGM concentrations did not differ in relation to role or handling. Foxes were most active at night; the time of peak activity did not vary with role or handling. Foxes were more active in winter; males were more active than females, and ambassador foxes were more active than off-exhibit animals. Hand-reared foxes were more sociable, and, at one institution, ambassador foxes were more sociable than foxes in other roles. These results suggest that management for ambassador programs is not associated with changes in glucocorticoid production or circadian patterns but may increase activity and be associated with greater sociability.