Fecal Glucocorticoid Measurements and Their Relation to Rearing, Behavior, and Environmental Factors in the Population of Pileated Gibbons (Hylobates pileatus) Held in European Zoos

Urinary oxytocin and cortisol concentrations vary by group type in male western lowland gorillas (Gorilla gorilla gorilla) in North American zoos

Evaluating how primates in human care function within their social environment is important for understanding and optimizing their management and welfare. The neuroendocrine hormone oxytocin is associated with affiliation and bonding, suggesting it can be used to evaluate the affiliative nature of social groupings. When paired with cortisol concentrations, social stressors can simultaneously be assessed, providing a more complete picture of primate social environments than if measuring either hormone independently. Here, we measured both oxytocin and cortisol in urine within a large subset of male western lowland gorillas (Gorilla gorilla gorilla; n = 71) living in North American zoos. Both endocrine measures were compared between social group types, with an emphasis on comparing bachelor and mixed-sex groupings to understand how these broad management practices affect male gorillas in zoos. Oxytocin concentrations were greater in bachelor group males than mixed-sex group males and singly housed males, providing physiological evidence that males in bachelor groups form comparatively stronger affiliative relationships than males in other group types. Cortisol concentrations did not differ between bachelor and mixed-sex group males and males in both group types had lower cortisol concentrations than singly housed males. These results indicate that males are similarly capable of coping with group-specific social stressors, and single management may expose males to additional stressors for which further study is needed. These data contribute to a larger body of research highlighting the value of bachelor groups from both a population management and individual welfare perspective.

The effects of visitors and social isolation from a peer on the behavior of a mixed-species pair of captive gibbons

Human visitors affect the behavior of captive animals, which is the so-called visitor effect. The number and behavior of visitors may influence stress-related behaviors in captive animals, such as self-scratching, yawning, and visitor-directed vigilance. A social group setting can be applied to alleviate such negative visitor effects and facilitate social behavior and interactions between individuals. In this study, we examined how the number and behavior of visitors are related to stress-related behaviors of a captive mixed-species gibbon pair comprising a yellow-cheek gibbon (Nomascus gabriellae) and a white-handed gibbon (Hylobates lar). The two gibbons were separated during the study period, and we examined whether the social isolation stimulated the visitor effect. The frequency of stress-related behaviors of the gibbons increased and the social playing between them decreased proportionally to visitor number. In the indoor enclosure, the gibbons increased their visitor-directed vigilance when visitors shouted or struck the glass partition. Our findings indicate that the number and behavior of visitors negatively affect captive gibbons and that a mixed-species social setting can help gibbons reduce visitor-induced stress. Future studies with larger sample sizes will improve the understanding of the visitor effect and the social setting in the captivity.

Validation of an enzyme immunoassay for measurement of fecal dehydroepiandrosterone sulfate in gibbons and siamangs

Monitoring wildlife stress levels is essential to ensure their quality of life in captivity or in the wild. One promising method to assess the stress response is the comeasurement of glucocorticoids (GC) and dehydroepiandrosterone sulfate (DHEAS), adrenal hormones involved in the modulation of the stress response. Although noninvasive methods to measure GCs have been validated in several species, only a few studies have validated DHEAS assays. The aims of this study were (1) to describe an enzyme immunoassay (EIA) to measure DHEAS levels, (2) to validate this assay for fecal samples in gibbons and siamangs, and (3) to test hormonal stability after one freeze-thaw cycle and over time at two freezer temperatures (-20°C and -80°C). Subjects included 32 gibbons and siamangs from U.S. zoological parks. The EIA was validated analytically by parallelism and accuracy tests, and biologically by confirming a DHEAS response 1-2 days after a stressful event (accident, vaccination, or transportation) in three individuals. In addition, fecal DHEAS levels in a pregnant female were above nonpregnant/nonlactating levels and declined progressively the following parturition. The hormonal stability experiments revealed no significant changes in fecal DHEAS levels after one freeze-thaw cycle. Hormonal levels in fecal extracts were stable for 2 months, regardless of the storage temperature, with no significant differences between -20°C and -80°C conditions. The EIA described has high sensitivity and it is suitable for fecal DHEAS measurement in gibbons and siamangs, with a potential to be applied to other species.

Looking beyond the Shoal: Fish Welfare as an Individual Attribute

Simple Summary

The fish farming industry is characterized by settings where large numbers of fishes are raised together at high stocking densities, effectively obliterating the individual. Given that animal welfare is an individual attribute that refers to how an animal experiences her world, it follows that ensuring good welfare for the different individuals is difficult in fish farms. In this paper we review evidence supporting the notion that fishes are individuals and fish welfare should thus also be considered at the individual level, examine the ways that animal welfare is assessed in fish farms, evaluate these practices in light of individualized terrestrial animal welfare assessment methods, and make recommendations regarding research that could lead to a better understanding of how to provide each individual fish with good welfare in captivity.

Abstract

Welfare is an individual attribute. In general, providing captive nonhuman animals with conditions conducive to good welfare is an idea more easily applied when dealing with few individuals. However, this becomes much harder—if not impossible—under farming conditions that may imply high numbers of animals living in large group sizes. Although this is a problem inherent to intensive animal farming, it is possibly best exemplified in fish farming, for these practices often rely on extremely high numbers. In this paper we review evidence supporting the notion that fishes are individuals and fish welfare should thus also be considered at the individual level, examine the current state of welfare assessment in the aquaculture industry, evaluate these practices in light of individualized terrestrial animal welfare assessment methods, and make recommendations regarding research that could lead to a better understanding of how to provide each individual fish with good welfare in captivity.

Social roles influence cortisol levels in captive Livingstone's fruit bats (Pteropus livingstonii)

A critical component of conserving and housing species ex situ is an explicit scientific understanding of the physiological underpinnings of their welfare. Cortisol has been repeatedly linked to stress, and therefore used as an indicator of welfare for many species. In order to measure cortisol in the Livingstone's fruit bat (Pteropus livingstonii; a critically endangered keystone species) without disturbing the captive population, we have developed and validated a non-invasive, novel hormone extraction procedure and faecal glucocorticoid assay. A total of 92 faecal samples, 73 from the P. livingstonii breeding colony at Jersey Zoo, Channel Islands and 19 samples from P. livingstonii housed at Bristol Zoological Gardens, UK, have been collected and analyzed. Mixed-effect modelling of the influence of physiological state variables on cortisol concentration revealed that lactating females had higher cortisol levels than non-lactating females, indicating that our assay is measuring biologically relevant hormone concentrations. Males and older bats also had higher cortisol than non-lactating females and younger individuals. Further analysis applied social network methodology to compare the cortisol levels of bats with different social roles. We found that individuals that linked social groups possessed higher than average cortisol levels and conversely, individuals with high-quality, positive relationships had lower cortisol levels. These results demonstrate, for the first time in a bat species, social mediation of stress hormones. Lastly, the frequency of vocalisation was found to positively correlate with cortisol concentration in males, suggesting that this behaviour may be used by animal management as a visual indicator of a bat's hormonal status. Hence, this research has provided unique insights and empirical scientific knowledge regarding the relationship between the physiology and social behaviour of P. livingstonii, therefore allowing for recommendations to be made to optimise bat welfare at the individual level.

Nonhuman primate abnormal behavior: Etiology, assessment, and treatment

Across captive settings, nonhuman primates may develop an array of abnormal behaviors including stereotypic and self-injurious behavior. Abnormal behavior can indicate a state of poor welfare, since it is often associated with a suboptimal environment. However, this may not always be the case as some behaviors can develop independently of any psychological distress, be triggered in environments known to promote welfare, and be part of an animal's coping mechanism. Furthermore, not all animals develop abnormal behavior, which has led researchers to assess risk factors that differentiate individuals in the display of these behaviors. Intrinsic risk factors that have been identified include the animal's species and genetics, age, sex, temperament, and clinical condition, while environmental risk factors include variables such as the animal's rearing, housing condition, husbandry procedures, and research experiences. To identify specific triggers and at-risk animals, the expression of abnormal behavior in captive nonhuman primates should be routinely addressed in a consistent manner by appropriately trained staff. Which behaviors to assess, what assessment methods to use, which primates to monitor, and the aims of data collection should all be identified before proceeding to an intervention and/or treatment. This article provides guidance for this process, by presenting an overview of known triggers and risk factors that should be considered, steps to design a comprehensive evaluation plan, and strategies that might be used for prevention or treatment. It also outlines the tools and processes for assessing and evaluating behavior in an appendix. This process will lead to a better understanding of abnormal behavior in captive primate colonies and ultimately to improved welfare.

Preliminary Findings on How Different Management Systems and Social Interactions Influence Fecal Glucocorticoid Metabolites in White Rhinoceros (Ceratotherium simum)

Simple Summary

In recent years, interest in improving the welfare of wild species in captivity has grown. The aim of this investigation was to evaluate the effects of different social environments and management systems on the cortisol secretion of fourteen white rhinoceroses (Ceratotherium simum) living under different conditions by using use noninvasive methods. The fecal glucocorticoid metabolite secretion was found to be affected by both management systems and social interactions. Additionally, sex is another factor that seems to influence. This research provides a deeper understanding of glucocorticoid production in white rhinoceroses, but more studies are needed to fully understand its influence on reproductive biology.

Abstract

White rhinoceroses (Ceratotherium simum) are the most social and gregarious species of all rhinoceroses known worldwide. One of the most critical effects of elevated glucocorticoid concentrations, especially in threatened species, is its relation to chronic stress, which could potentially lead to immunosuppression and reduced reproductive activity. Our aim is to determine how different social environments and management systems might be influencing the secretion of fecal glucocorticoids in white rhinoceroses. We have analyzed the concentration of fecal glucocorticoid metabolites in 658 fecal samples from 14 white rhinoceroses, seven free-ranging rhinos, and seven rhinos from two different managed captive populations. HPLC techniques were used to determine the main glucocorticoid metabolite found in this species, and a competitive EIA was used to establish fecal 5α-pregnan-3 3β, 11β, 21-triol-20-oneglucocorticoid metabolite (fGCM) levels. Our results reveal that management systems and social interactions had an influence on fGCM levels, suggesting that the more restrictive the management and social conditions are, the higher the glucocorticoid concentrations that are found. Additionally, sex was also found to influence fGCM levels, as in females, fGCM concentrations were higher than in males. We conclude that the analysis of glucocorticoids in relation to other factors is a powerful tool to assess adrenocortical response in white rhinoceros in order to broaden the knowledge of their reproductive biology and improve the management of the species.

Hair cortisol in captive corral-housed baboons

Hair cortisol concentrations (HCCs) are measures of long-term hypothalamic-pituitary-adrenocortical (HPA) activity and can be used as indicators of chronic stress. However, intrinsic factors such as an animal's age and sex can also have an impact on resulting HCCs. Although baboons are commonly studied in captivity, little is known about baseline HCC in this population. Here we measured HCC in two same-sex groups of captive olive (Papio hamadryas anubis) baboons and olive/yellow baboon (Papio hamadryas cynocephalus) crosses housed in large outdoor corrals, and we assessed the impact of age and sex on HCC as major variables of interest. Hair was gently shaved from the back of the neck when the animals were sedated for routine physicals. Subjects were divided into three age categories: juvenile (2-4 years), adult (9-12 years), and senior (13-19 years). The "senior" category contained only males. Results confirm an effect of sex and age on HCCs. Females had higher levels of hair cortisol than males, and juveniles had higher levels than adults. There was also a significant sex × age interaction. There were no sex differences in HCCs in juveniles, but there was a greater decline in HCCs in adult males than in adult females. Within males, there was a significant difference in levels of hair cortisol across the three age categories. Juveniles had higher levels than did adults and seniors, but adults and seniors were not significantly different from one another. These results provide baseline measures of hair cortisol in captive baboons and demonstrate effects of sex and age on HCCs.

Comparison of the Glucocorticoid Concentrations between Three Species of Lemuridae Kept in a Temporary Housing Facility

We compared the glucocorticoid concentrations in response to various types of potential stressors present during standard operation of a temporary housing facility between three species, namely, ring-tailed lemurs, collared brown lemurs and white-headed lemurs. The levels of faecal glucocorticoid metabolites (FGMs) were measured non-invasively on a daily basis during a 30-day period. A total of 510 faecal samples were collected. Concentrations of immunoreactive glucocorticoid hormone metabolites were measured in the obtained extracts by using an enzyme immunoassay. The polyclonal antibodies used in this assay were directed against the metabolite 11-oxo-etiocholanolone I. We found all three monitored lemur species to respond to specific potentially stressful situations by increasing (p < 0.05) the FGM levels within one to two days after the event. Although housed in the same room, differences in response to potentially stressful situations were found in white-headed lemurs compared to ring-tailed lemurs. Increased mean levels of the FGMs were found more frequently in white-headed lemurs than in ring-tailed lemurs. The results suggest that this species may be more sensitive to changes in its surroundings. In general, the levels of the FGMs showed a similar pattern during 30 days of monitoring suggesting that all groups of lemurs responded in a similar manner to the same events. However, we recorded the differences in the absolute values of glucocorticoid concentrations between the monitored species likely due to the differences in sex ratios in the groups and presence of lactating females in the ring-tailed lemurs.

Physical and Physiological Indicators of Welfare in Guinea Pigs (Cavia porcellus) Serving as Ambassador Animals

Special encounters that allow contact between animals and guests are common in zoos and aquariums. Visitors to the Saint Louis Zoo may touch guinea pigs serving as ambassador animals. We evaluated two welfare indicators in ambassador guinea pigs by comparing glucocorticoid levels and body weights between periods when guinea pigs lived in a habitat accessible to the public and while off exhibit. Mean glucocorticoid levels did not differ between sexes or between on- and off-exhibit periods. There was significant individual variation, and females demonstrated greater variation than males. While on exhibit, glucocorticoid levels slightly but significantly increased in males and decreased in females. Moving guinea pigs between habitats only elicited a significant glucocorticoid response when females were moved off exhibit. Temporary closures of the exhibit had no effect on glucocorticoid levels in either sex. Analyses of the impact of handling rates on males found no impact on glucocorticoid levels. Guinea pigs' body weights were lower while on exhibit. We conclude that guinea pigs serving as ambassador animals at the Saint Louis Zoo demonstrate comparable physiological profiles while on and off exhibit and, when used in a rotational schedule, are a suitable species for animal encounters involving contact with the public.

Biochemical and biological validations of a faecal glucocorticoid metabolite assay in mandrills (Mandrillus sphinx)

Stress is a major factor in determining success when releasing endangered species into the wild but is often overlooked. Mandrills (Mandrills sphinx) are vulnerable to extinction due to habitat loss and demand for bush meat and the pet trade. To help bolster in situ populations, rehabilitated rescued mandrills recently were released into a protected area in the Republic of Congo. The goal of this study was to validate the use of faecal glucocorticoid metabolite enzyme immunoassays (EIAs) in mandrills and test field-friendly faecal hormone extraction techniques that can subsequently be used to monitor the stress physiology and welfare of mandrills throughout the release process. Using faecal samples collected from ex situ mandrills, we tested cortisol, corticosterone, 11β-hydroxyetiocholanolone (69a), and 11-oxoetiocholanolone EIAs. Absolute concentrations, hormone profiles following medical procedures or translocation, and high-performance liquid chromatography fraction immunoreactivity showed that the 69a assay was the best choice to monitor the stress response in this species. Samples with delayed extraction or drying times had 40-80% lower 69a concentrations than samples extracted immediately post-collection and frozen. The 69a EIA is an appropriate assay for monitoring welfare in this species in situ or ex situ, and results indicated that consistent extraction methods are important for accurate comparisons.

Individual, social, and environmental factors affecting salivary and fecal cortisol levels in captive pied tamarins (Saguinus bicolor)

Pied tamarins (Saguinus bicolor) are endangered New World primates, and in captivity appear to be very susceptible to stress. We measured cortisol in 214 saliva samples from 36 tamarins and in 227 fecal samples from 27 tamarins, and investigated the effects of age, sex, pregnancy, rearing history, social status, weight, group composition, and enclosure type using generalized linear mixed models. There was no effect of age on either fecal or salivary cortisol levels. Female pied tamarins in late pregnancy had higher fecal cortisol levels than those in early pregnancy, or nonpregnant females, but there was no effect of pregnancy on salivary cortisol. Females had higher salivary cortisol levels than males, but there was no effect of rearing history. However, for fecal cortisol, there was an interaction between sex and rearing history. Hand-reared tamarins overall had higher fecal cortisol levels, but while male parent-reared tamarins had higher levels than females who were parent-reared, the reverse was true for hand-reared individuals. There was a trend towards lower fecal cortisol levels in subordinate individuals, but no effect of status on salivary cortisol. Fecal but not salivary cortisol levels declined with increasing weight. We found little effect of group composition on cortisol levels in either saliva or feces, suggesting that as long as tamarins are housed socially, the nature of the group is of less importance. However, animals in off-show enclosures had higher salivary and fecal cortisol levels than individuals housed on-show. We suggest that large on-show enclosures with permanent access to off-exhibit areas may compensate for the effects of visitor disturbance, and a larger number of tamarins of the same species housed close together may explain the higher cortisol levels found in tamarins living in off-show accommodation, but further research is needed.

The Visitor Effect on Zoo Animals: Implications and Opportunities for Zoo Animal Welfare

Simple Summary

Research has shown that an animal’s welfare is highly dependent on how various individual animal factors (e.g., species traits, genetics, temperament and previous experience) interact with environmental features (e.g., social grouping, enclosure design and sensory environment). One prominent feature of a zoo’s environment is the presence of visitors. Decades of research on the visitor effect in zoos has demonstrated that visitors can have negative, neutral or positive impacts on zoo animal behaviour and welfare. This paper reviews the literature on the implications and potential opportunities of human–zoo animal interactions on animal behaviour and welfare, with the aim of stimulating interest, understanding and exploration of this important subject.

Abstract

Achieving and maintaining high standards of animal welfare is critical to the success of a modern zoo. Research has shown that an animal’s welfare is highly dependent on how various individual animal factors (e.g., species traits, genetics, temperament and previous experience) interact with environmental features (e.g., social grouping, enclosure design and sensory environment). One prominent feature of the zoo environment is the presence of visitors. Visitor contact can be unpredictable and intense, particularly in terms of auditory and visual interaction. Depending on an animal’s perception of this interaction, visitors can have either negative, neutral or positive impacts on zoo animal behaviour and welfare. This paper reviews the literature on the implications and potential opportunities of human-zoo animal interactions on animal behaviour and welfare, with the aim of stimulating interest, understanding and exploration of this important subject. The literature to date presents a mixed range of findings on the topic. It is possible this variation in the responses of zoo animals to visitors may be due to species-specific differences, the nature and intensity of the visitor interactions, enclosure design, and individual animal characteristics. Analysing these studies and better understanding animal preferences and motivations can provide insight into what animals find negatively and positively reinforcing in terms of visitor contact in a specific zoo setting. This understanding can then be applied to either safeguard welfare in cases where visitors can have a negative impact, or, conversely, it can be applied to highlight opportunities to encourage animal-visitor interaction in situations where animals experience positive emotions associated with visitor interaction.

The effects of transport stress on the behaviour and adrenocortical activity of the black-and-white ruffed lemur (Varecia variegata)

The aim of this study was to assess behavioural and glucocorticoid changes in black-and-white ruffed lemur females transported for breeding purposes between Czech ZOOs. The frequency of the presented behaviour elements was recorded via direct observation. The faecal samples were collected from the floor and subsequently the faecal glucocorticoid values were determined using specifically designed assays for faecal glucocorticoid metabolite (FGM) analysis. While the frequency of certain comfort behaviour patterns decreased (P < 0.05) in response to transport and change of the environment, grooming, resting, sleeping as well as playful behaviour (chasing, climbing) were not affected (P > 0.05). No changes were found in the frequency of behaviour connected to metabolic events with the exception of defecation. Lemur females defecated more frequently (P < 0.05) in their new environment. The frequency of neither fear nor exploratory behaviour differed (P > 0.05) before and after transport. The positive effect of the novelty was shown by the reduction (P < 0.01) of behavioural signs of frustration and stereotypical behaviour after transport. In response to transport, a significant (P < 0.05) increase of FGM levels was found the second day after the transport, reaching peak levels in the morning and starting to decline to baseline levels in the afternoon. The results of both behaviour and adrenocortical activity analysis suggest that despite some presented changes in the monitored indices prior and after transport, the transportation under the studied conditions presented only a mild stressor with limited behavioural and glucocorticoid responses.

The 24/7 approach to promoting optimal welfare for captive wild animals

We have an ethical responsibility to provide captive animals with environments that allow them to experience good welfare. Husbandry activities are often scheduled for the convenience of care staff working within the constraints of the facility, rather than considering the biological and psychological requirements of the animals themselves. The animal welfare 24/7 across the lifespan concept provides a holistic framework to map features of the animal's life cycle, taking into account their natural history, in relation to variations in the captive environment, across day and night, weekdays, weekends, and seasons. In order for animals to have the opportunity to thrive, we argue the need to consider their lifetime experience, integrated into the environments we provide, and with their perspective in mind. Here, we propose a welfare assessment tool based upon 14 criteria, to allow care staff to determine if their animals' welfare needs are met. We conclude that animal habitat management will be enhanced with the use of integrated technologies that provide the animals with more opportunities to engineer their own environments, providing them with complexity, choice and control.

Group size and visitor numbers predict faecal glucocorticoid concentrations in zoo meerkats

Measures of physiological stress in zoo animals can give important insights into how they are affected by aspects of their captive environment. We analysed the factors influencing variation in glucocorticoid metabolites in faeces (fGCs) from zoo meerkats as a proxy for blood cortisol concentration, high levels of which are associated with a stress response. Levels of fGCs in captive meerkats declined with increasing group size. In the wild, very small groups of meerkats are at a higher risk of predation, while in larger groups, there is increased competition for resources. Indeed, group sizes in captivity resemble those seen in unstable coalitions in the wild, which may represent a stressful condition and predispose meerkats to chronic stress, even in the absence of natural predators. Individuals in large enclosures showed lower levels of stress, but meerkat density had no effect on the stress measures. In contrast with data from wild meerkats, neither sex, age nor dominance status predicted stress levels, which may reflect less food stress owing to more equal access to resources in captivity versus wild. The median number of visitors at the enclosure was positively correlated with fGC concentrations on the following day, with variation in the visitor numbers having the opposite effect. Our results are consistent with the hypothesis that there is an optimum group size which minimizes physiological stress in meerkats, and that zoo meerkats at most risk of physiological stress are those kept in small groups and small enclosures and are exposed to consistently high numbers of visitors.

Effect of weather conditions and presence of visitors on adrenocortical activity in captive African penguins (Spheniscus demersus)

A number of potential stressors are present in captive environments and it is critically important to identify them in order to improve health and welfare in ex situ animal populations. In this study, we investigated the adrenocortical activity of a colony of African penguins hosted in an immersive zoo in Italy, with respect to the presence of visitors and local microclimatic conditions, using the non-invasive method of assessing faecal glucocorticoid metabolites (FGMs). The penguins' exhibit is a large naturalistic outdoor enclosure, which closely reproduces the natural habitat of this species. Data collection took place from the beginning of June to the end of August 2014, during the period of maximum flow of visitors. We carried out 12 sampling periods, each involving 2 consecutive days; during the first day we counted the visitors and we registered the meteorological data, and on the second day, we collected the faecal samples, which amounted to a total of 285 faecal samples. Our results showed that the number of visitors did not influence the adrenocortical activity of the African penguins. Conversely, the local microclimatic conditions did influence the physiological stress on these birds. We found that an increase of the daily mean temperature induced a significant increase in FGM concentrations, although humidity and wind speed had a moderating effect on temperature and reduced the heat-induced stress. Moreover, we calculated two climatic indices, commonly used to assess the thermal discomfort in animals, namely the THI (Temperature-Humidity Index) and WCI (Wind Chill Index), and we detected a positive relationship between their values and the FGM levels, demonstrating that these indices could be useful indicators of weather discomfort in African penguins. Our study shows that the simulating naturalistic conditions could have significant benefits for zoo animals, such as reducing the negative effect of visitors. Nevertheless, it should be taken into account where the zoological facility is located and if the local microclimatic conditions are compatible with the hosted species, to ensure that they do not differ greatly from their natural habitat.

Tailored Enrichment Strategies and Stereotypic Behavior in Captive Individually Housed Macaques (Macaca spp.)

The welfare of nonhuman animals in captivity is widely dependent on the natural psychological, physical, and behavioral needs of the animals and how adequately these needs are met. Inability to engage in natural behaviors can lead to chronic stress and expression of stereotypic behavior. The majority of research on decreasing stereotypic behavior in captivity addresses problems at the group level and does not account for individual variability in each animal's needs, history, and preferences. This study combined physiological and behavioral measures of well being to comprehensively assess the unique needs of individually housed captive macaques (Macaca spp.) with the aim of developing tailored welfare strategies. Behavioral and hormonal data were collected under 2 conditions: baseline and individualized enrichment. The results showed a significant decrease in stereotypic behavior under the enrichment condition. Additionally, 7 out of 9 individuals showed a decrease in fecal glucocorticoid (stress hormone) levels, indicating a reduction in hypothalamic-pituitary-adrenal activity. Addressing welfare on an individual, rather than group, level allows for a better overall characterization of well being and maximizes the probability of improving the welfare of each animal.

Evaluating capture stress in wild gray mouse lemurs via repeated fecal sampling: method validation and the influence of prior experience and handling protocols on stress responses

Reliable measurements of physiological stress are increasingly needed for eco-physiological research and for species conservation or management. Stress can be estimated by quantifying plasma glucocorticoid levels, but when this is not feasible, glucocorticoid metabolites are often measured from feces (FGCM). However, evidence is accumulating on the sensitivity of FGCM measurements to various nuisance factors. Careful species- and context-specific validations are therefore necessary to confirm the biological relevance and specificity of the method. The goals of this study were to: (1) establish and validate sampling methods and an enzymeimmunoassay to measure FGCM in the gray mouse lemur (Microcebus murinus); (2) explore causes of variability in the FGCM measurements, and; (3) assess the consequences of capturing and handling for free-living individuals by quantifying their stress responses via repeated fecal sampling within capture sessions. We further assessed the influence of different handling protocols and the animals' previous capture experience on the magnitude of the physiological response. Our validations identified the group-specific measurement of 11ß-hydroxyetiocholanolone as the most suitable assay for monitoring adrenocortical activity. The sample water content and the animal's age were found to significantly influence baseline FGCM-levels. Most captured animals exhibited a post-capture FGCM-elevation but its magnitude was not related to the handling protocol or capture experience. We found no evidence for long-term consequences of routine capturing on the animals' stress physiology. Hence the described methods can be employed to measure physiological stress in mouse lemurs in an effective and relatively non-invasive way.

Cues to androgens and quality in male gibbon songs

Animal vocal signals may provide information about senders and mediate important social interactions like sexual competition, territory maintenance and mate selection. Hence, it is important to understand whether vocal signals provide accurate information about animal attributes or status. Gibbons are non-human primates that produce loud, distinctive and melodious vocalizations resembling more those of birds than of other non-human primates. Wild gibbons are characterized by flexibility in social organization (i.e., pairs and multimale units) as well as in mating system (i.e., monogamy and polyandry). Such features make them a suitable model to investigate whether the physiology (hormonal status) and socio-demographic features find their correspondence in the structure of their songs. By combining male solo song recordings, endocrine outputs using non-invasive fecal androgen measures and behavioral observations, we studied 14 groups (10 pair-living, 4 multimale) of wild white-handed gibbons (Hylobates lar) residing at Khao Yai National Park, Thailand. We collected a total of 322 fecal samples and recorded 48 songs from 18 adult animals. Our results confirmed inter-individuality in male gibbon songs, and showed a clear correlation between androgen levels and song structures. Gibbons with higher androgen levels produced calls having higher pitch, and similarly adult individuals produced longer calls than senior males. Thus, it is plausible that gibbon vocalizations provide receivers with information about singers' attributes.

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.

Non-invasive monitoring of physiological stress in the Western lowland gorilla (Gorilla gorilla gorilla): validation of a fecal glucocorticoid assay and methods for practical application in the field

Enzymeimmunoassays (EIAs) allow researchers to monitor stress hormone output via measurement of fecal glucocorticoid metabolites (FGCMs) in many vertebrates. They can be powerful tools which allow the acquisition of otherwise unobtainable physiological information from both captive animals and wild animals in remote forest habitats, such as great apes. However, methods for hormone measurement, extraction and preservation need to be adapted and validated for field settings. In preparation for a field study of Western lowland gorillas (Gorilla gorilla gorilla) in the Central African Republic we used samples from captive gorillas collected around opportunistic stressful situations to test whether four different glucocorticoid EIAs reflected adrenocortical activity reliably and to establish the lag-time from the stressor to peak excretion. We also validated a field extraction technique and established a simple, non-freezer-reliant method to preserve FGCMs in extracts long-term. We determined the rate of FGCM change over 28 days when samples cannot be extracted immediately and over 12h when feces cannot be preserved immediately in alcohol. Finally, we used repeat samples from identified individuals to test for diurnal variation in FGCM output. Two group-specific assays measuring major cortisol metabolites detected the predicted FGCM response to the stressor reliably, whereas more specific cortisol and corticosterone assays were distinctly less responsive and thus less useful. We detected a lag time of 2-3 days from stressor to peak FGCM excretion. Our field extraction method performed as well as an established laboratory extraction method and FGCMs in dried extracts stored at ambient temperatures were as stable as those at -20 °C over 1 yr. Hormones in non-extracted feces in alcohol were stable up to 28 days at ambient temperatures. FGCMs in un-fixed gorilla feces deteriorated to almost 50% of the original values within 6h under field conditions. We detected no diurnal variation in FGCMs in samples from wild gorillas. Our study highlights the importance of thorough biological and immunological validation of FGCM assays, and presents validated, practical methods for the application of non-invasive adrenocortical monitoring techniques to field conservation contexts where it is crucially needed.