Long‐term storage effects in steroid metabolite extracts from baboon ( Papio sp.) faeces – a comparison of three commonly applied storage methods

Analytical and biological validation of a noninvasive measurement of glucocorticoid metabolites in feces of Geoffroy's spider monkeys (Ateles geoffroyi)

We report on an analytical and biological validation of a commercial cortisol enzyme immunoassay (EIA) to measure glucocorticoids (GC) in feces of Geoffroy's spider monkeys (Ateles geoffroyi). Validation of endocrinological methods for each sample matrix and study species is crucial to establish that the methods produce reliable results. For the analytical validation of the EIA, we assessed parallelism, accuracy, and precision. We carried out a biological validation based on three well-studied GC patterns with the following predictions: (1) increased fecal GC metabolite (fGCM) concentrations after veterinary intervention; (2) increased fGCM concentrations during early morning hours; and (3) higher fGCM concentrations during gestation than in other female reproductive states. For the first prediction, we sampled feces of two zoo-housed females 2 days before, the day of, and 2 days after a veterinary intervention. For the second prediction, we analyzed 284 fecal samples collected from 12 wild males using a linear mixed model (LMM). For the third prediction, we analyzed 269 fecal samples of eight wild females using an LMM. Analytical validation revealed that the EIA showed parallelism, was accurate, and precise within each assay. However, there was elevated variation in between-assay precision. The biological validation supported all predictions: (1) the two zoo-housed females showed a substantial increase in fGCM concentrations 2.5 and 11 h after veterinary intervention; (2) there was a negative effect of sample collection time on fGCM concentrations (i.e., higher concentrations during early morning); (3) gestating females had significantly higher fGCM concentrations than lactating females. Thus, we analytically validated the commercial EIA and, despite between-assay variation, we were able to find three biologically relevant GC signals in captive and wild settings, and in males and females. We are therefore confident that the method can be used to noninvasively address behavioral endocrinology questions in Geoffroy's spider monkeys.

Associations between fecal cortisol and biparental care in a pair-living primate

OBJECTIVES

We quantified variation in fecal cortisol across reproductive periods in Azara's owl monkeys (Aotus azarae) to examine physiological mechanisms that may facilitate biparental care. Specifically, we evaluated evidence for the explanation that owl monkeys have hormonal mechanisms to mobilize energy during periods when each sex is investing heavily in reproduction, that is, the gestation period for females and the infant care period for males.

MATERIALS AND METHODS

Between 2011 and 2015, we monitored 10 groups of Azara's owl monkeys from a wild population in Formosa, Argentina and collected fecal samples from 26 adults (13 males, 13 females). Using enzyme-linked immunosorbent assays, we quantified fecal cortisol as a proxy for evaluating stress responses, including energetic demands, on both sexes during periods of reproduction and parental care.

RESULTS

Male cortisol was lowest during periods when they were caring for young infants (<3 months) compared with periods with older infants or no infant. Female cortisol was elevated during gestation compared with other periods. Mean fecal cortisol in both males and females was lower when an infant was present compared with when females were gestating.

DISCUSSION

Our results do not support the hypothesis that owl monkey males have elevated fecal cortisol during periods when they need to mobilize energy to provide intensive infant care. Our findings are also inconsistent with the Maternal Relief hypothesis. However, results from studies measuring fecal cortisol must be interpreted with care and alternative explanations, such as seasonal fluctuations in diet and thermoenergic demands, should be considered when drawing conclusions.

Life on the edge: behavioural and physiological responses of Verreaux's sifakas (Propithecus verreauxi) to forest edges

Forest edges change micro-environmental conditions, thereby affecting the ecology of many forest-dwelling species. Understanding such edge effects is particularly important for Malagasy primates because many of them live in highly fragmented forests today. The aim of our study was to assess the influence of forest edge effects on activity budgets, feeding ecology, and stress hormone output (measured as faecal glucocorticoid metabolite - fGCM - levels) in wild Verreaux's sifakas (Propithecus verreauxi), a group living, arboreal lemur. We observed five habituated groups: three living in the forest interior and two at an established forest edge. There was no difference in average daily temperatures between edge and interior habitats; however, within the edge site, the average daily temperature incrementally increased over 450 m from the forest edge towards the interior forest of the edge habitat, and the population density was lower at the edge site. Activity budgets differed between groups living in the two microhabitats, with individuals living near the edge spending more time travelling and less time feeding. Groups living near the edge also tended to have smaller home ranges and core areas than groups in the forest interior. In addition, edge groups had elevated average fGCM concentrations, and birth rates were lower for females living in the edge habitat. Combined with lower levels of fruit consumption at the edge, these results suggest that nutritional stress might be a limiting factor for Verreaux's sifakas when living near a forest edge. Hence, Verreaux's sifakas appear to be sensitive to microhabitat characteristics linked to forest edges; a result with implications for the conservation of this critically endangered lemurid species.

Response of Bolivian gray titi monkeys (Plecturocebus donacophilus) to an anthropogenic noise gradient: behavioral and hormonal correlates

Worldwide urban expansion and deforestation have caused a rapid decline of non-human primates in recent decades. Yet, little is known to what extent these animals can tolerate anthropogenic noise arising from roadway traffic and human presence in their habitat. We studied six family groups of titis residing at increasing distances from a busy highway, in a park promoting ecotourism near Santa Cruz de la Sierra, Bolivia. We mapped group movements, sampled the titis’ behavior, collected fecal samples from each study group and conducted experiments in which we used a mannequin simulating a human intrusion in their home range. We hypothesized that groups of titi monkeys exposed to higher levels of anthropogenic noise and human presence would react weakly to the mannequin and show higher concentrations of fecal cortisol compared with groups in least perturbed areas. Sound pressure measurements and systematic monitoring of soundscape inside the titis’ home ranges confirmed the presence of a noise gradient, best characterized by the root-mean-square (RMS) and median amplitude (M) acoustic indices; importantly, both anthropogenic noise and human presence co-varied. Study groups resided in small, overlapping home ranges and they spent most of their time resting and preferentially used the lower forest stratum for traveling and the higher levels for foraging. Focal sampling analysis revealed that the time spent moving by adult pairs was inversely correlated with noise, the behavioral change occurring within a gradient of minimum sound pressures ranging from 44 dB(A) to 52 dB(A). Validated enzyme-immunoassays of fecal samples however detected surprisingly low cortisol concentrations, unrelated to the changes observed in the RMS and M indices. Finally, titis’ response to the mannequin varied according to our expectation, with alarm calling being greater in distant groups relative to highway. Our study thus indicates reduced alarm calling through habituation to human presence and suggests a titis’ resilience to anthropogenic noise with little evidence of physiological stress.

Urinary suPAR: a non-invasive biomarker of infection and tissue inflammation for use in studies of large free-ranging mammals

Studies of large free-ranging mammals incorporating physiological measurements typically require the collection of urine or faecal samples, due to ethical and practical concerns over trapping or darting animals. However, there is a dearth of validated biomarkers of immune activation and inflammation that can be measured non-invasively. We here evaluate the utility of urinary measurements of the soluble form of the urokinase plasminogen activator receptor (suPAR), for use as a health marker in studies of wild large mammals. We investigate how urinary suPAR concentrations change in response to viral infection and surgical trauma (inflammation), comparing it to the measurement of a marker of cellular immune activation, urinary neopterin (uNEO), in captive rhesus macaques. We then test the field utility of urinary suPAR, assessing the effects of soil and faecal contamination, sunlight, storage at different temperatures, freeze-thaw cycles, and lyophilization. We find that suPAR concentrations rise markedly in response to both infection and surgery-associated inflammation, unlike uNEO concentrations, which only rise in response to the former. Our field validation demonstrates that urinary suPAR is reasonably robust to many of the issues associated with field collection, sample processing, and storage, as long as samples can be stored in a freezer. Urinary suPAR is thus a promising biomarker applicable for monitoring various aspects of health in wild primates and potentially also other large mammals.

Altitude and human disturbance are associated with helminth diversity in an endangered primate, Procolobus gordonorum

Gastrointestinal parasites colonizing the mammalian gut influence the host immune system and health. Parasite infections, mainly helminths, have been studied intensively in both humans and non-human animals, but relatively rarely within a conservation framework. The Udzungwa red colobus monkey (Procolobus gordonorum) is an endangered endemic primate species living in the Udzungwa Mountains of Tanzania, a global biodiversity hotspot. Since this endemic primate species is highly sensitive to human disturbance, here we investigate whether habitat type (driven by natural and human-induced factors) is associated with helminth diversity. Using standard flotation and sedimentation techniques, we analyzed 251 fecal samples belonging to 25 social groups from four different forest blocks within the Udzungwa Mountains. Five parasitic helminth taxa were recovered from Udzungwa red colobus, including Trichuris sp., Strongyloides fulleborni, S. stercoralis, a strongylid nematode and Colobenterobius sp. We used Generalized Linear Mixed Models to explore the contribution of habitat type, altitude and fecal glucocorticoid levels (as biomarkers of stress) in predicting gut parasite variation. Although some parasites (e.g., Trichuris sp.) infected more than 50% of individuals, compared to others (e.g., Colobenterobius sp.) that infected less than 3%, both parasite richness and prevalence did not differ significantly across forests, even when controlling for seasonality. Stress hormone levels also did not predict variation in parasite richness, while altitude could explain it resulting in lower richness at lower altitudes. Because human activities causing disturbance are concentrated mainly at lower altitudes, we suggest that protection of primate forest habitat preserves natural diversity at both macro- and microscales, and that the importance of the latter should not be underestimated.

Temporal profiles of cortisol accumulation and clearance support scale cortisol content as an indicator of chronic stress in fish

The development of chronic stress indicators for fish is of great interest, but appropriate non-invasive methods are lagging those used in terrestrial vertebrates. Here, we explore the possibility that levels of the stress hormone cortisol in scales could be used as a chronic stress indicator. Three experiments were conducted to assess the temporal profiles of cortisol rise and fall in plasma and scales of goldfish (Carassius auratus) in response to stressors of varying intensity and duration. Results show that a single acute air emersion stressor does not influence scale cortisol content. In contrast, relative to plasma levels, the fall in scale cortisol content following a high-dose cortisol implant is delayed by at least 8 days, and the rise and fall in scale cortisol content in response to unpredictable chronic stress are delayed by at least 7 days. Also, scale cortisol content is spatially heterogeneous across the body surface of goldfish. Overall, since high and sustained circulating cortisol levels are needed to influence scale cortisol content and the rates of cortisol accumulation and clearance are much slower in scales than in plasma, our results show that scales can provide an integrated measure of cortisol production and serve as a chronic stress indicator.

Opportunities and challenges associated with fecal progesterone metabolite analysis

Conventionally, plasma or milk progesterone evaluations are used to determine the reproductive status of female animals. Collection of such samples is often associated with difficulties of animal handling and restraint. Measurable quantities of progesterone metabolites are found in feces of animals. Their concentrations are known to be well correlated to plasma progesterone levels and are, therefore, used as non-invasive samples for assessing reproductive function in a wide range of animal species. Although the analysis of fecal progesterone metabolites has been widely accepted in many laboratories, several factors are known to affect the results from this valuable analytical technique. Some of these factors include storage/transportation media for fecal samples, type of solvent that is used for extraction of progesterone metabolites from feces, and the type and sensitivity of an assaying technique employed. Although fecal progesterone metabolites analysis is associated with some difficulties, it can effectively be used to monitor reproductive function in a wide range of animal species. This review aims to highlight the usefulness of fecal progesterone metabolite analysis as a non-invasive technique in monitoring reproductive function in animals. The article mainly focuses on the many opportunities and challenges associated with this analytical technique.

Comparison of fecal preservation and extraction methods for steroid hormone metabolite analysis in wild crested macaques

Since the non-invasive field endocrinology techniques were developed, several fecal preservation and extraction methods have been established for a variety of species. However, direct adaptation of methods from previous studies for use in crested macaques should be taken with caution. We conducted an experiment to assess the accuracy and stability of fecal estrogen metabolite (E1C) and glucocorticoid metabolite (GCM) concentrations in response to several preservation parameters: (1) time lag between sample collection and fecal preservation; (2) long-term storage of fecal samples in 80% methanol (MeOH) at ambient temperature; (3) different degrees of feces drying temperature using a conventional oven; and (4) different fecal preservation techniques (i.e., freeze-drying, oven-drying, and field-friendly extraction method) and extraction solvents (methanol, ethanol, and commercial alcohol). The study used fecal samples collected from crested macaques (Macaca nigra) living in the Tangkoko Reserve, North Sulawesi, Indonesia. Samples were assayed using validated E1C and GCM enzyme immunoassays. Concentrations of E1C and GCM in unprocessed feces stored at ambient temperature remained stable for up to 8 h of storage after which concentrations of both E1C and GCM changed significantly compared to controls extracted at time 0. Long-term storage in 80% MeOH at ambient temperature affected hormone concentrations significantly with concentrations of both E1C and GCM increasing after 6 and 4 months of storage, respectively. Drying fecal samples using a conventional oven at 50, 70, and 90 °C did not affect the E1C concentrations, but led to a significant decline for GCM concentrations in samples dried at 90 °C. Different fecal preservation techniques and extraction solvents provided similar results for both E1C and GCM concentrations. Our results confirm previous studies that prior to application of fecal hormone analysis in a new species, several preservation parameters should be evaluated for their effects on hormone metabolite stability. The results also provide several options for fecal preservation, extraction, and storage methods that can be selected depending on the condition of the field site and laboratory.

Meerkat close calling patterns are linked to sex, social category, season and wind, but not fecal glucocorticoid metabolite concentrations

It is well established that animal vocalizations can encode information regarding a sender's identity, sex, age, body size, social rank and group membership. However, the association between physiological parameters, particularly stress hormone levels, and vocal behavior is still not well understood. The cooperatively breeding African meerkats (Suricata suricatta) live in family groups with despotic social hierarchies. During foraging, individuals emit close calls that help maintain group cohesion. These contact calls are acoustically distinctive and variable in rate across individuals, yet, information on which factors influence close calling behavior is missing. The aim of this study was to identify proximate factors that influence variation in call rate and acoustic structure of meerkat close calls. Specifically, we investigated whether close calling behavior is associated with sex, age and rank, or stress hormone output (i.e., measured as fecal glucocorticoid metabolite (fGCM) concentrations) as individual traits of the caller, as well as with environmental conditions (weather) and reproductive seasonality. To disentangle the effects of these factors on vocal behavior, we analyzed sound recordings and assessed fGCM concentrations in 64 wild but habituated meerkats from 9 groups during the reproductive and non-reproductive seasons. Dominant females and one-year old males called at significantly higher rates compared to other social categories during the reproductive season. Additionally, dominant females produced close calls with the lowest mean fundamental frequencies (F0) and the longest mean pulse durations. Windy conditions were associated with significantly higher call rates during the non-reproductive season. Fecal GCM concentrations were unrelated to close calling behavior. Our findings suggest that meerkat close calling behavior conveys information regarding the sex and social category of the caller, but shows no association with fGCM concentrations. The change in call rate in response to variation in the social and ecological environments individuals experience indicates some degree of flexibility in vocal production.

Non-invasive monitoring of physiological markers in primates

The monitoring of endocrine markers that inform about an animal's physiological state has become an invaluable tool for studying the behavioral ecology of primates. While the collection of blood samples usually requires the animal to be caught and immobilized, non-invasively collected samples of saliva, urine, feces or hair can be obtained without any major disturbance of the subject of interest. Such samples enable repeated collection which is required for matching behavioral information over long time periods with detailed information on endocrine markers. We start our review by giving an overview of endocrine and immune markers that have been successfully monitored in relation to topics of interest in primate behavioral ecology. These topics include reproductive, nutritional and health status, changes during ontogeny, social behavior such as rank relationships, aggression and cooperation as well as welfare and conservation issues. We continue by explaining which hormones can be measured in which matrices, and potential problems with measurements. We then describe different methods of hormone measurements and address their advantages and disadvantages. We finally emphasize the importance of thorough validation procedures when measuring a specific hormone in a new species or matrix.

Validation of a field-friendly extraction and storage method to monitor fecal steroid metabolites in wild orangutans

Measuring hormone metabolites from feces is the most often used method to assess hormonal status in wildlife. Although immediate freezing of fecal samples collected in the field is the best method to minimize the risk of degradation of hormones over time, this is often not possible in remote field sites. Therefore, alternative storage and preservation methods for fecal samples are required in these conditions. We conducted an experiment to investigate if fecal glucocorticoid (FGCM) and progesterone metabolite (pregnanediol-3-glucuronide; PdG) levels measured from samples that were extracted with a simple, field-friendly methodology correlate with those generated from frozen samples. We also evaluated whether storing fecal samples in alcohol is a suitable alternative to preserve FGCM and PdG concentrations long-term (i.e. over a 9-month period) at locations where fecal extraction is not feasible. Finally, we tested if the hormone concentrations in unpreserved fecal samples of orangutans change over 14 h when stored at ambient conditions, representing the maximum duration between sample collection and return to the camp. FGCM and PdG levels measured from samples that were extracted with the field-friendly method showed strong correlations with those generated from frozen samples, and mean levels did not differ significantly between these methods. FGCM concentrations showed no significant change compared to control samples when fecal samples were stored for up to 6 months in alcohol at ambient temperature and PdG concentrations even remained stable for up to 9 months of storage. FGCM concentrations of fecal samples kept at ambient temperature for up to 14 h post-defecation did not significantly differ compared to control samples frozen immediately after collection. These results provide the basis for the successful monitoring of the physiological status of orangutans living in remote natural settings, like those included in the Indonesian reintroduction programs.

Field endocrinology of nonhuman primates: past, present, and future

In the past few decades, research on nonhuman primate endocrinology has moved from the lab to the field, leading to a huge increase in both the breadth and depth of primate field studies. Here, I discuss the past, present, and future of primate field endocrinology. I review the history of the field, and go on to discuss methodological developments and the issues that they sometimes entail. Next, I consider ways in which we might conceptualize the role of hormones, and focus on the need to distinguish proximate from ultimate levels of explanation. Current potentially problematic issues in the field include: 1) an inability to obtain noninvasive measurements of Central Nervous System (CNS) rather than peripheral hormone concentrations; 2) research questions that become stuck (e.g., questions regarding sexual swelling expression mechanisms); 3) data dredging and post-hoc linking of hormones to any plausible variable, leading to a lack of clarity on their role in animal ecology and behavior. I finish by discussing several unanswered questions that might benefit from further research. These are how we might: 1) best obtain measurements for CNS hormone concentrations non-invasively; 2) measure hormone receptor expression alongside hormone concentrations; 3) consider the human endocrinology literature more thoroughly and perhaps take more multimarker approaches; 4) better consider the social environment, including audience and dyadic familiarity effects; and 5) apply our findings to conservation issues.

Maximizing the reliability of non-invasive endocrine sampling in the tiger (Panthera tigris): environmental decay and intra-sample variation in faecal glucocorticoid metabolites

Evaluation of physiological stress in the tiger (Panthera tigris) using faecal cortisol metabolite (FCM) enzyme immunoassays (EIAs) provides a powerful conservation physiology tool for the species. However, it is important to validate non-invasive endocrine sampling techniques in field conditions to ensure that the method provides a reliable parameter of physiological stress in the species. This is because endocrine measurements are highly species specific and FCM concentrations can be influenced by environmental factors. Here, we studied the impact of the decay rate of FCMs and intra-sample variation of FCMs using a previously validated EIA. To determine the decay rate of FCMs, we measured FCMs in freshly deposited tiger faeces (n = 8 tigers and 48 scats) that were randomly exposed to the natural environment (dry conditions with no rainfall) for up to 192 h. To determine intra-sample variation in FCMs, we used 10 scats from 10 tigers, divided each sample into four sections and each section into four sub-sections and measured FCMs in each section and sub-section. The results of this decay-rate experiment showed that FCMs in tiger faeces began to decay after 48 h exposure to the environmental conditions available. Thus, FCMs within freshly deposited tiger faeces are influenced by available environmental conditions. Changes in weather conditions (e.g. increased rainfall and humidity) could influence the stability of FCMs. The results of the intra-sample variation study showed that inter-variation among scats accounted for 52% of the variations in FCMs, while intra-sample variation between sections (32%) was greater than the sub-sample variation (16%). Intra-sample variation can be reduced by homogenizing the entire lyophilized faecal sample prior to the EIA. In conclusion, careful evaluation of decay rate and complete homogenization of faeces prior to EIA analysis will increase the reliability of FCMs as a non-invasive index of physiological stress in the tiger.

Urinary neopterin, a non-invasive marker of mammalian cellular immune activation, is highly stable under field conditions

Studying immunity and immune function in ecology and evolution requires field studies, but there has been a dearth of non-invasive markers of immune activation available for studying large wild mammals. Recently, we analytically and biologically validated the measurement of urinary neopterin (NEO), a biomarker of cellular immune activation, in captive macaques. However, applying this to free-ranging settings is complicated by issues involving sample collection, processing, storage, and transport. Here, we collected urine samples from captive macaques and undertook experiments simulating common field issues. We tested the effects on urinary NEO sample measurements following: dirt and faecal contamination; storage at room temperature; differences in processing and long-term storage methods (freezing, lyophilising, blotting onto filter paper); and freeze-thaw cycles. Our results show that concentrations of urinary NEO are highly stable--they are not affected by soil or faecal contamination, can be collected on filter paper and stored for many months frozen or lyophilised with minimal effect, and are resistant to multiple 24 hr freeze-thaws. With the addition of a biocidal preservative, concentrations are even stable at room temperature for long periods. Urinary NEO is remarkably resilient, and is highly suitable for non-invasive field studies of cellular immune responses in wild large mammals.

Social behavior and patterns of testosterone and glucocorticoid levels differ between male chacma and Guinea baboons

In multi-male, multi-female groups of mammals, males usually compete aggressively over access to females. However, species vary in the intensity of male contest competition, which has been linked to differences in testosterone and glucocorticoid profiles. Chacma (Papio ursinus) and Guinea (P. papio) baboons constitute an intriguing model to examine variation in male competition and male endocrine correlates, because of the differences in their social systems. Chacma baboons live in stable female-bonded groups with linear male dominance hierarchies and a high male mating skew, whereas Guinea baboons live in male-bonded, multi-level societies. We recorded male behavior and assayed testosterone (fT) and glucocorticoid metabolite (fGC) levels from fecal samples in one population of each species. Male chacma baboons were more frequently involved in agonistic interactions, and dominance relationships were more consistent than in Guinea baboons, where we could not detect linear hierarchies. Notably, male chacma baboons were also more aggressive towards females, indicating an overall higher aggressiveness in this species. In contrast, male Guinea baboons showed higher levels of affiliative interactions and spatial tolerance. High-ranking and consorting male chacma baboons showed elevated fGC levels and also tended to show elevated fT levels, but there was no effect of consortship in Guinea baboons. Agonism was not related to hormone levels in either species. Thus, predictors of fT and fGC levels in Guinea baboons seem to differ from chacma baboons. Our results support the view that different social systems create differential selection pressures for male aggression, reflected by different hormone profiles.

Measuring stress responses in female Geoffroy's spider monkeys: Validation and the influence of reproductive state

Fecal glucocorticoid metabolites are increasingly used to investigate physiological stress. However, it is crucial for researchers to simultaneously investigate the effects of reproductive state because estradiol and placental hormones can affect circulating glucocorticoid concentrations. Reports on the relationships between glucocorticoids and reproductive state are inconsistent among females. Unlike several primate species that have heightened glucocorticoid activity during lactation, humans experience reduced glucocorticoid activity during lactation. Rather than a taxonomic difference, we hypothesize that this is a result of different environmental stressors, particularly the threat of infanticide. Here, we expand the number of wild primate species tested by validating a glucocorticoid assay for female Geoffroy's spider monkeys. We investigate the effects of reproductive state on their glucocorticoid concentrations. Utilizing a routine veterinary exam on a captive population, we determined that fecal glucocorticoid metabolites increase in response to a stressor (anesthesia), and this rise is detected approximately 24 hr later. Additionally, we found that extracted hormone patterns in a wild population reflected basic reproductive biology-estradiol concentrations were higher in cycling than lactating females, and in lactating females with older offspring who were presumably resuming their cycle. However, we found that estradiol and glucocorticoid concentrations were significantly correlated in lactating but not cycling females. Similarly, we found that reproductive state and estradiol concentration, but not stage of lactation, predicted glucocorticoid concentrations. Unlike patterns in several other primate species that face a relatively strong threat of infanticide, lactating spider monkeys experience reduced glucocorticoid activity, possibly due to attenuating effects of oxytocin and lower male-initiated aggression than directed at cycling females. More broadly, we conclude that future studies using fecal glucocorticoid metabolites to index stress should consider that reproductive state might confound glucocorticoid measurements. Am. J. Primatol. 77:925-935, 2015. © 2015 Wiley Periodicals, Inc.

Use of salivary cortisol to evaluate the influence of rides in dromedary camels

Animals in captivity and in the wild face numerous challenges, including the risk of enduring acute or chronic stress. In captivity, facilities attempt to alleviate the risk of chronic stress by providing environmental enrichment, shown to minimize behavioral disorders and stress in several species. One potential form of enrichment in zoos is training animals to provide rides for guests, however, the effect of this activity on the welfare of individual animals has never been examined. We validated the use of saliva for assessing stress in dromedary camels (Camelus dromedarius), an animal commonly used for rides. We then measured variation in salivary cortisol in four male camels while providing rides of differing frequency for guests at the Toronto Zoo. The camels were sampled during the ride season (June to September) using four treatments: (1) in their pasture, (2) at the ride area when not performing rides, (3) while providing a low number of rides (n=50/day) and (4) while providing a high number of rides (n=150/day). Furthermore, samples were taken before and after the ride season for comparison. There was a significant difference between the post-ride season treatment and the three treatments involving guest presence during the ride season (ride area, low rides, high rides). In general, cortisol concentrations were lower during the ride season and higher during the non-ride season. Based on the metrics we used, performing rides is not a stressful experience for these dromedary camels and suggests that rides may be a form of enrichment.

Validation of an enzyme immunoassay for assessing adrenocortical activity and evaluation of factors that affect levels of fecal glucocorticoid metabolites in two New World primates

Non-invasive methods to assess stress hormone output via fecal glucocorticoid metabolites (FGCMs) have become a powerful tool in behavioral studies and conservation biology because they allow exploring the link between behavior, an animal's socio-ecological environment and its adrenocortical activity. However, FGCM levels are influenced by numerous other factors which often confound their interpretation. Thus, before applying these methods, knowledge on the impact of these factors is important. In this study we investigated the effect of (1) time of day, (2) age, (3) sex and (4) female reproductive state on FGCM levels in brown spider monkeys (Ateles hybridus) and red howler monkeys (Alouatta seniculus). Initially, we validated a 11β-hydroxyetiocholanolone enzyme immunoassay for monitoring the physiological stress response via fecal analysis in both species. We determined FGCM levels in fecal samples collected from two and six groups of wild spider monkeys (n=461 samples) and howler monkeys (n=166 samples), respectively. Our analyses revealed a strong effect of time of day on FGCM levels in spider monkeys, but no effect in howler monkeys. Adults of both species had significantly higher FGCM levels than subadults. In neither of the two species we found a sex-effect on FGCM output. Reproductive condition strongly affected FGCM levels in female spider monkeys which showed increasing concentrations with progressing gestation. This was not investigated in female howler monkeys due to an insufficient sample size. Our data indicate that the influence of the tested factors on fecal glucocorticoid metabolite output is species-specific, and that these variables need to be considered when interpreting FGCM levels in the species.

Methodological Considerations in the Analysis of Fecal Glucocorticoid Metabolites in Tufted Capuchins (Cebus apella)

Analysis of fecal glucocorticoid (GC) metabolites has recently become the standard method to monitor adrenocortical activity in primates noninvasively. However, given variation in the production, metabolism, and excretion of GCs across species and even between sexes, there are no standard methods that are universally applicable. In particular, it is important to validate assays intended to measure GC production, test extraction and storage procedures, and consider the time course of GC metabolite excretion relative to the production and circulation of the native hormones. This study examines these four methodological aspects of fecal GC metabolite analysis in tufted capuchins (Cebus apella). Specifically, we conducted an adrenocorticotrophic hormone (ACTH) challenge on one male and one female capuchin to test the validity of four GC enzyme immunoassays (EIAs) and document the time course characterizing GC metabolite excretion in this species. In addition, we compare a common field-friendly technique for extracting fecal GC metabolites to an established laboratory extraction methodology and test for effects of storing "field extracts" for up to 1 yr. Results suggest that a corticosterone EIA is most sensitive to changes in GC production, provides reliable measures when extracted according to the field method, and measures GC metabolites which remain highly stable after even 12 mo of storage. Further, the time course of GC metabolite excretion is shorter than that described yet for any primate taxa. These results provide guidelines for studies of GCs in tufted capuchins, and underscore the importance of validating methods for fecal hormone analysis for each species of interest.