Noninvasive Measures of Reproductive Function and Disturbance in the Barred Owl, Great Horned Owl, and Northern Spotted Owl

Validation of Fecal Glucocorticoid Metabolites as Non-Invasive Markers for Monitoring Stress in Common Buzzards (Buteo buteo)

For wild animals, being in captivity in wildlife centers can cause considerable stress. Therefore, it is necessary to establish and validate non-invasive tools to measure chronic stress during rehabilitation. Eight Common Buzzards which lived in permanent husbandry were placed individually into prepared aviaries and their feces were collected before, during and after a stress event for biological validation over a period of seven days. The extracted fecal glucocorticoid metabolites (fGCMs) were analyzed with three different enzyme immune assays (EIA) to find the most suitable one. Additionally, we aimed to investigate the stability of fGCM levels after defecation because further metabolization by bacterial enzymes can lead to changed results. The Cortisone-EIA performed best in males and females and showed that the stress event led to an fGCM increase of 629% (557% in females and 702% in males) in relation to basal values. We found no significant differences between the sexes, but observed significant differences between different times of day. FGCM concentration significantly changed after eight hours at room temperature. Our study successfully validated the non-invasive measurement of fGCM as a stress indicator in Common Buzzards and could therefore lay the foundation for future studies providing new insights for animal welfare research in Buzzards.

Validation of enzyme immunoassays for quantifying sex steroid hormones in tropical screech owls (Megascops choliba)

Androgens and estrogens are steroid hormones that regulate reproductive processes in both males and females. Monitoring plasma levels of these steroids or their metabolites present in feces, offers diagnostic support for assessing the reproductive status of animals. Immunoassays are commonly used methods for quantifying these hormones, but their protocols require species-specific validation to ensure reliability. The objective of this study was to perform analytically and biologically validation of enzyme immunoassay (EIA) kits for measuring testosterone (T), estradiol (E2), faecal androgen metabolites (fAM), and faecal estrogenic metabolites (fEM) in the tropical screech owl (Megascops choliba). Serum and fecal samples were collected from six adult females and six males both before and during breeding season, with males' gonadal activity assessed using electroejaculation (EE). The parallelism test confirmed the immunogenic similarity of the antigens in the estradiol and testosterone standards and the antigens in the serum samples and fecal extracts of M. choliba. Additionally, the EIA kits displayed nearly 100% recovery rates, and showed coefficients of variation ranging from 8% to 14% at the intra-assay level and from 10% to 16% at the inter-assay level, underscoring result reliability and consistency. In males, the highest serum T and fAM levels were recorded concurrently with the presence of spermatozoa in samples collected via EE. Although females did not exhibit oviposition events, significantly higher E2 and fEM levels were observed in August compared to May, suggesting potential seasonal variations in estrogenic hormone production. Fecal androgen and estrogen levels were significantly different between sexes in August, with males having higher fAM and females having higher fEM levels. Overall, the immunoassays validated in this study were found to be efficient in diagnosing reproductive activity in owls.

Glucocorticoid metabolites in an ex situ nocturnal bird, the tropical screech owl Megascops choliba: effects of sex, activity period and inter-individual variation

Glucocorticoids mediate physiological processes to obtain energy, presenting daily variation in basal levels that may be related to behavioural activity pattern. Identification of plasticity in the secretion of these hormones is essential to understand their effects on physiology and behaviour of wild birds and, therefore, their success in their natural or artificial environment. Serial endocrine evaluations are facilitated by implementing non-invasive methodologies that minimize possible effects of manipulation on the animal's physiological variables. However, non-invasive endocrine-behavioural studies in nocturnal birds, such as owls, are immature. The present work aimed to validate an enzyme immunoassay (EIA) to quantify glucocorticoid metabolites (MGC) in Megascops choliba as well as to evaluate differences in their production at the individual, sexual or daily level. We recorded the behaviour of nine owls during three continuous days to establish activity budget under captive conditions and aiming to correlate with daily MGC variation. The EIA proved to be effective in analytical assays and in pharmacological testing with synthetic ACTH, validating this immunoassay for the species. Additionally, individual differences in MGC production were confirmed in relation to the time of day, especially at 1700 and 2100, but not in relation to sex. During night hours, the owls showed greater behavioural activity, positively related to MGC values. Higher MGC concentrations were significantly related to greater expressions of active behaviours, such as maintenance, while lower MGC concentrations were recorded during moments of higher alertness and resting. The results presented show daily MGC variation to be inversed in this nocturnal species. Our findings can aid future theoretical studies of daily rhythm and evaluations of challenging and/or disturbing situations that result in changes in behaviour or hormonal cascades of these changes in ex situ populations of owls.

Fecal glucocorticoid analysis as a health monitoring tool for endangered African penguins (Spheniscus demersus)

African penguins (Spheniscus demersus) are an endangered species, with approximately 70,000 mature adults remaining in the wild. Population loss is linked to a combination of environmental and anthropogenic stressors. The aim of the study was to validate a commercially available enzyme immunoassay (EIA) to assess adrenal activity and measure the response to stressors in the feces of African penguins. Fecal samples (n = 609) were collected from 12 African penguins housed at Mystic Aquarium throughout their natural lifecycle, including breeding and molt, where measurable changes in fecal glucocorticoid metabolite (FGM) levels are predicted to occur. Fecal samples collected post-veterinary exam were used for biological validation. Longitudinal analysis shows a significant difference (p = <0.0001) between the average FGM levels during baseline and breeding season, 33.97 ± 1.30 ng/g and 50.21 ± 3.18 ng/g, respectively. Females displayed significantly higher FGM levels than males during both baseline (p = 0.0386; females = 38.80 ± 2.19 ng/g; males = 29.34 ± 1.37 ng/g) and breeding periods (p = 0.0175; females = 57.53 ± 4.84 ng/g; males = 42.69 ± 3.95 ng/g). Average FGM levels decreased significantly over the three-week molting period, from 85.40 ± 20.35 ng/g at week one to 20.23 ± 5.30 ng/g at week three. A seasonal difference in FGM levels was observed in both male and female fecal samples, with Fall having the highest average FGM levels, 54.38 ± 3.64 ng/g, and Summer the lowest, 30.87 ± 2.21 ng/g. General linear mixed model analysis determined that lifecycle (females) and visitor presence (males) were the two factors which best explained the variation in FGM levels observed, however neither factor was found to be significant. These results show FGM analysis can detect physiologically meaningful changes in endocrine activity in African penguins and can be used to monitor health for penguins in aquaria and in the wild, thus contributing to conservation efforts for the survival of the species.

Physiological and behavioural assessments of stress levels in owls housed at owl cafes

Owl cafes, where customers view and interact with owls, have become popular in Japan. There are multiple aspects of the environment which may be stressful to nocturnal owls, including lighting, tethering and frequent interactions with humans but, to date, welfare has not been investigated. This preliminary study examines the effects of owl cafes and customers on the physiological stress (faecal corticosterone levels [FCL]) and behaviour of the owls. Seven eagle owls (Bubo bubo ) and two African scops owls (Ptilopsis leucotis), in two cafes, were studied over an eight-day period. Cafe A (n = 5) was closed for one day per week, whilst cafe B (n = 4) was open every day. In cafe A there was higher FCL in owls during open days than closed days suggesting that the conditions on open days increase stress in owls. Eight of nine owls showed evidence of some aversion or avoidance of humans, whilst no affiliative behaviours were observed. The number of visitor interactions was not associated with the level of physiological stress; and when comparing owls, there was a tendency for individual owls with a higher percentage of aversive responses to customers to also have higher FCL. Close human interactions of a negative nature, that result in aversion, may be a significant stressor, but further research is required.

Effects of faecal inorganic content variability on quantifying glucocorticoid and thyroid hormone metabolites in large felines: Implications for physiological assessments in free-ranging animals

Faecal glucocorticoid (GC) and triiodothyronine (T3) metabolites and their interactions are increasingly used to monitor perceived stress and nutritional challenges in free-ranging animals. However, a number of extrinsic and intrinsic factors including hormone-inert dietary materials, inorganic matters etc. are known to affect reliable hormone metabolite quantifications. In this study, the impacts of inorganic matter (IOM) on faecal GC (fGCMs) and T3 (fT3Ms) metabolite measure were addressed in wild tiger (n = 193 from Terai Arc landscape, India) and captive lion (n = 120 from Sakkarbaug Zoological Garden, Gujarat, India) and possible corrective measures were evaluated. The wild tiger samples contained highly variable IOM content (9-98%, mostly with > 40% IOM) compared to captive Asiatic lion (17-57%, majority with < 40% IOM). Significant correlations were observed between IOM content and tiger fGCM (r = -0.46, p = 0.000), fT3M (r = -0.58, p = 0.000) and lion fT3M measures (r = -0.43, p = 0.003). Two corrective measures viz. removing samples with ≥ 80% IOM and subsequently expressing concentrations as per gram of organic dry matter (instead of total dry matter) reduced IOM influence on tiger fGCM, fT3M and lion fT3M, without affecting lion fGCM measures. The corrective measures changed the interpretations of fT3M data of field-collected tiger samples with no significant changes in fGCM (both tiger and lion) and fT3M (lion) data. As faecal IOM content is common in many wild species, the results emphasize the need to reduce IOM-driven hormone data variation for ecologically relevant interpretations towards species conservation.

Investigation of keratinase digestion to improve steroid hormone extraction from diverse keratinous tissues

Monitoring the physiology of wild populations presents many technical challenges. Blood samples, long the gold standard of wildlife endocrinology studies, cannot always be obtained. The validation and use of non-plasma samples to obtain hormone data have greatly improved access to more integrated information about an organism's physiological state. Keratinous tissues like skin, hair, nails, feathers, or baleen store steroid hormones in physiologically relevant concentrations, are stable across decades, and can be used to retrospectively infer physiological state at prior points in time. Most protocols for steroid extraction employ physical pulverization or cutting of the sample, followed by mixing with a solvent. Such methods do produce repeatable and useful data, but low hormone yield and detectability issues can complicate research on small or rare samples. We investigated the use of keratinase, an enzyme that breaks down keratin, to improve the extraction and yield of corticosterone from vertebrate keratin tissues. Corticosterone content of keratinase-digested extracts were compared to non-keratinase extracts for baleen from three species of whale (blue, Balaenoptera musculus; bowhead, Balaena mysticetus; southern right, SRW; Eubalaena australis), shed skin from two reptiles (tegu lizard, Salvator merianae; narrow-headed garter snake, Thamnophis rufipunctatus), hair from arctic ground squirrel (AGS; Urocitellus parryii), feathers from Purple Martins (PUMA; Progne subis), and spines from the short-beaked echidna (Tachyglossus aculeatus). We tested four starting masses (10, 25, 50, 100 mg) for each sample; digestion was most complete in the 10 and 25 mg samples. A corticosterone enzyme immunoassay (EIA) was validated for all keratinase-digested extracts. In all sample types except shed skin from reptiles, keratinase digestion improved hormone yield, with PUMA feathers and blue whale baleen having the greatest increase in apparent corticosterone content (100% and 66% more hormone, respectively). The reptilian shed skin samples did not benefit from keratinase digestion, actually yielding less hormone than controls. With further optimization and refinement, keratinase digestion could greatly improve yield of steroid hormones from various wildlife epidermal tissue types, allowing more efficient use of samples and ultimately improving understanding of the endocrine physiology of wild populations.

Scales of our lives: Sex identification of Temminck's pangolin (Smutsia temminckii) using scales retrieved out of the illegal wildlife trade

Pangolins are the most trafficked wild mammals, with their scales in high demand. Scales are often the only part of the animal confiscated from the trade, but they represent accessible material for forensic investigations, including for sexing. This study aimed to develop a sexing tool for Temminck's pangolin, using scales for hormone quantification. Scales from males and females were liquidised using keratinase and the resulting suspension analysed for progestagen and androgen metabolite (scPM and scAM) concentrations. Scale PM and scAM concentrations were compared between sexes, while overall median values for scPM and scAM, as well as a ratio of scPM to scAM (P/A) were used as boundary values for sex identification. Neither scPM nor scAM concentrations were significantly different between the sexes and concentrations of a juvenile and sub-adult male overlapped with females, possibly indicating later sexual maturity in males. Boundary values for scAM concentrations and the P/A ratio predicted sex with 100% accuracy for females and 78% for males, while the accuracies for the scPM boundary value were lower. When only adult individuals are considered, scAM and P/A ratio boundaries are 100% accurate for both sexes. Therefore, scale hormone ratios show promise as a sex identification tool for Temminck's pangolin, particularly applicable in forensic investigations on the pangolin trade.

Fecal stress, nutrition and reproductive hormones for monitoring environmental impacts on tigers (Panthera tigris)

Non-invasive stress and nutritional hormone analysis in relation to ecological and other biological indices have tremendous potential to address environmental disturbance impacts on wildlife health. To this end, we examined the relation between glucocorticoid (GC) and thyroid (T3) hormone indices of disturbance and nutritional stress in response to ACTH and TSH challenges in captive tigers, as well as how reproductive hormones vary by sex and reproductive condition. Glucocorticoid, thyroid, progesterone and androgen assays conducted on high-performance liquid chromatography separated fractions of biologically relevant fecal extracts revealed high cross-reactivity of these assays for their respective biologically relevant fecal hormone metabolites. Both adrenal and thyroid hormone metabolites were elevated in response to ACTH and TSH challenges. However, the adrenal and thyroid hormone responses to ACTH challenge were concurrent, whereas the adrenal response to TSH challenge was delayed relative to thyroid hormone elevation in both males and females. The concurrently elevated T3 in response to ACTH may serve to raise metabolic rate to maximize use of GC-mobilized glucose, whereas the relatively delayed GC rise following TSH challenge may be a response to glucose depletion due to increased metabolic rate associated with elevated T3. Progesterone, testosterone and androstenedione hormone metabolites were significantly elevated during gestation compared to lactation in a female monitored from conception through early lactation. Results suggest that the glucocorticoid, thyroid and reproductive hormone assays we tested can accurately measure the stress, nutrition and reproductive response from tiger feces, providing useful non-invasive tools to assess physiological responses to environmental stressors and their reproductive consequences in the wild.

Female gonadal hormones and reproductive behaviors as key determinants of successful reproductive output of breeding whooping cranes (Grus americana)

Reproductive success of endangered whooping cranes (Grus americana) maintained ex situ is poor. As part of an effort to identify potential causes of poor reproductive success in a captive colony, we used non-invasive endocrine monitoring to assess gonadal and adrenal steroids of bird pairs with various reproductive outcomes and evaluated the relationships of hormones and behaviors to reproductive performance. Overall, reproductively successful (i.e., egg laying) females had significantly higher mean estrogen levels but lower mean progestogen concentrations than did unsuccessful females. Other hormones, including glucocorticoids and androgens, were not significantly different between successful and unsuccessful individuals. Observations of specific behaviors such as unison calling, marching, and the number of copulation attempts, along with overall time spent performing reproductive behaviors, were significantly higher in successful pairs. Our findings indicate that overall reproductive performance of whooping crane pairs is linked to female gonadal hormone excretion and reproductive behaviors, but not to altered adrenal hormone production.

Physiology in conservation translocations

Conservation translocations aim to restore species to their indigenous ranges, protect populations from threats and/or reinstate ecosystem functions. They are particularly important for the conservation and management of rare and threatened species. Despite tremendous efforts and advancement in recent years, animal conservation translocations generally have variable success, and the reasons for this are often uncertain. We suggest that when little is known about the physiology and wellbeing of individuals either before or after release, it will be difficult to determine their likelihood of survival, and this could limit advancements in the science of translocations for conservation. In this regard, we argue that physiology offers novel approaches that could substantially improve translocations and associated practices. As a discipline, it is apparent that physiology may be undervalued, perhaps because of the invasive nature of some physiological measurement techniques (e.g. sampling body fluids, surgical implantation). We examined 232 publications that dealt with translocations of terrestrial vertebrates and aquatic mammals and, defining 'success' as high or low, determined how many of these studies explicitly incorporated physiological aspects into their protocols and monitoring. From this review, it is apparent that physiological evaluation before and after animal releases could progress and improve translocation/reintroduction successes. We propose a suite of physiological measures, in addition to animal health indices, for assisting conservation translocations over the short term and also for longer term post-release monitoring. Perhaps most importantly, we argue that the incorporation of physiological assessments of animals at all stages of translocation can have important welfare implications by helping to reduce the total number of animals used. Physiological indicators can also help to refine conservation translocation methods. These approaches fall under a new paradigm that we term 'translocation physiology' and represent an important sub-discipline within conservation physiology generally.

Enzyme immunoassays as a method for quantifying hair reproductive hormones in two felid species

Non-invasive monitoring of wild felid reproductive states is important, given that many species reproduce poorly in captivity. Despite extensive work in faecal hormone analysis in felids, continued development of techniques is necessary, particularly with wild populations. In this study, our aims were as follows: (i) biochemical validation of enzyme immunoassays for estrogen, testosterone and progesterone in Canada lynx and domestic cat hair extracts; (ii) assessment of the use of hair reproductive hormones to differentiate between reproductive states (intact, estrus, pregnant and spayed/neutered), using domestic cats as a model; and (iii) assessment of the use of hair reproductive hormones to differentiate between age and sex, accounting for potential regional variability in wild lynx populations. Analysis of hair hormone levels showed prospective value in detecting pregnancy states, with pregnant domestic cats having higher levels of progesterone than spayed females. However, intact and pregnant cats did not differ in progesterone levels. Yet, two female domestic cats had higher levels of hair progesterone following a 38-day oral progestin treatment, perhaps providing a preliminary pharmacological validation of the method. Estrogen and testosterone did not differ statistically according to reproductive states of domestic cats, although intact males had higher levels of hair testosterone than neutered males. When we applied these techniques to lynx fur, we determined that hormone levels were not sufficiently precise to differentiate age classes. Hair reproductive hormone ratios differed between sexes, with the estrogen-to-progesterone ratio demonstrating the highest accuracy in differentiating males from females. Hair hormone levels differed regionally for wild lynx, indicating that spatial variability should be a consideration in wildlife hormone studies spanning large spatial scales. We conclude that use of hair hormone analysis by enzyme immunoassay may hold promise for differentiating sex in felids, but the technique will require further refinement and validation before it can be applied broadly and reliably.

Longitudinal monitoring of sex steroid hormones in excrement of spectacled eiders (Somateria fischeri)

From the 1970s to the 1990s, the breeding population of spectacled eiders (Somateria fischeri) in western Alaska declined by 96%, which led to the listing of this species as threatened under the Endangered Species Act in 1993. Since then, the population has stabilized, but has not recovered to pre-decline numbers. While little is known about reproductive endocrinology in spectacled eiders, in other avian species, estrogen and testosterone are known to initiate and modulate various reproductive processes including yolk protein synthesis, reproductive behaviors and secondary sex characteristics. Measurement of the metabolites of estrogen and testosterone (EM and TM, respectively) in excrement reflect circulating hormone concentrations and provide a non-invasive method to monitor reproductive physiology. We measured concentrations of excreted EM in captive females and TM in males to (1) determine the efficacy of commercially available radioimmunoassay kits to detect EM and TM, (2) describe annual profiles of EM and TM concentrations, and (3) define the reproductive season of captive spectacled eiders using endocrine status. Excrement samples were collected from captive female and male spectacled eiders three times per week throughout 1 year. Female EM and male TM levels were quantified using radioimmunoassay. Mean female EM profile exhibited values exceeding the threshold for "peak" values (EM>193.3 ng/g) from mid-February to early July, and again in September. Additionally, the highest average concentrations of EM were seen in March, May and September. Elevated TM concentrations occurred in mid March, mid May and late June. These data suggest that levels of excreted sex steroids reflect patterns predicted by breeding landmarks in the annual cycle and will assist in field monitoring and captive breeding programs for spectacled eiders.

The effect of ACTH upon faecal glucocorticoid excretion in the koala

Environmental changes result in physiological responses of organisms, which can adversely affect population dynamics and reduce resistance to disease. These changes are expressed in chronic levels of stress. The measurement of glucocorticoid (GC) concentrations in faeces is a non-invasive method for monitoring stress in wildlife. The metabolism and excretion of steroids differ significantly between species and, as a consequence, non-invasive methods must be physiologically validated for each species. Koalas (Phascolarctos cinereus) are declining in numbers through much of their range. The role of chronic stress in koala populations has not been identified. Prior to the assessment of faecal GC concentrations in wild koala populations, the excretion timing and concentrations of GCs need to be determined. In this study, we assessed a method for identifying and measuring the concentrations of GC metabolites in faecal pellets of captive koalas following ACTH treatment. The results show that an elevation of plasma cortisol concentrations, using sustained release of ACTH, results in elevated concentrations of faecal cortisol/cortisol metabolites. Taking into account the excretion time lag, an increase in faecal cortisol metabolite concentrations corresponds to the release of GCs from the adrenal cortex as early as 36 h before faecal pellet collection. The calculations of steroid partitioning of plasma cortisol showed that the ACTH-stimulated values were significantly different from the control values for the concentrations of free, corticosteroid-binding globulin-bound and albumin-bound cortisol. This study validates the use of faecal cortisol analysis to assess the activity of the hypothalamo-pituitary-adrenocortical axis in freshly collected koala faecal pellets and indicates that the method should be suitable to assess the adrenocortical status of koalas in wild populations.

Non-invasive monitoring of glucocorticoid physiology within highland and lowland populations of native Australian Great Barred Frog (Mixophyes fasciolatus)

This study used non-invasive endocrinology to examine baseline corticosterone at different altitudes in a free-living Australian amphibian: the Great Barred Frog (Mixophyes fasciolatus). An enzyme immunoassay (EIA) was performed on urine samples and validated biologically using an adrenocorticotropic hormone (ACTH) challenge. Frogs were injected with ACTH on day 0 and recaptures occurred 1-10days post injection. Urine samples and body condition measurements were collected from lowland (60m) and highland (660m and 790m) sub-populations of M. fasciolatus in South East Queensland (SEQ), close to their post-breeding period during autumn 2011. We simultaneously sampled these sub-populations for Batrachochytrium dendrobatidis (Bd), a pathogenic fungus responsible for mass mortalities of amphibians worldwide. The ACTH challenge successfully validated the urinary corticosterone EIA in M. fasciolatus, with a peak urinary corticosterone response to ACTH injection on day 2 and a return to baseline levels by day 6. Polymerase chain reaction (PCR) analysis of 50 individuals returned only 1 positive result for Bd. Simple linear regression showed a strong positive relationship between baseline urinary corticosterone concentrations and altitude and no relationship with body condition. We hypothesize that higher baseline corticosterone concentrations within highland sub-populations of male M. fasciolatus could be associated with increased environmental challenge at high altitudes and geographic range limits. Whether this pattern is an indication of chronic stress in highland populations or life-time fitness and survival, warrants future investigation.

Using detection dogs to conduct simultaneous surveys of northern spotted (Strix occidentalis caurina) and barred owls (Strix varia)

State and federal actions to conserve northern spotted owl (Strix occidentalis caurina) habitat are largely initiated by establishing habitat occupancy. Northern spotted owl occupancy is typically assessed by eliciting their response to simulated conspecific vocalizations. However, proximity of barred owls (Strix varia)–a significant threat to northern spotted owls–can suppress northern spotted owl responsiveness to vocalization surveys and hence their probability of detection. We developed a survey method to simultaneously detect both species that does not require vocalization. Detection dogs (Canis familiaris) located owl pellets accumulated under roost sites, within search areas selected using habitat association maps. We compared success of detection dog surveys to vocalization surveys slightly modified from the U.S. Fish and Wildlife Service’s Draft 2010 Survey Protocol. Seventeen 2 km ×2 km polygons were each surveyed multiple times in an area where northern spotted owls were known to nest prior to 1997 and barred owl density was thought to be low. Mitochondrial DNA was used to confirm species from pellets detected by dogs. Spotted owl and barred owl detection probabilities were significantly higher for dog than vocalization surveys. For spotted owls, this difference increased with number of site visits. Cumulative detection probabilities of northern spotted owls were 29% after session 1, 62% after session 2, and 87% after session 3 for dog surveys, compared to 25% after session 1, increasing to 59% by session 6 for vocalization surveys. Mean detection probability for barred owls was 20.1% for dog surveys and 7.3% for vocal surveys. Results suggest that detection dog surveys can complement vocalization surveys by providing a reliable method for establishing occupancy of both northern spotted and barred owl without requiring owl vocalization. This helps meet objectives of Recovery Actions 24 and 25 of the Revised Recovery Plan for the Northern Spotted Owl.

Variation in the Extraction Efficiency of Estradiol and Progesterone in Moist and Lyophilized Feces of the Black Howler Monkey (Alouatta pigra): Alternative Methods

Several fecal steroid extraction techniques have been developed to measure the ovary function in different species of mammals. However, regardless of the method of extraction and the sample type chosen, it has been observed that they can yield results with different percentages of recuperation. The objective of this study was to determine whether the type of substratum, solvent and extraction method used have any influence on the extraction efficiency in the feces of Alouatta pigra (black howler monkey). For this purpose we used two methods: agitation and ebullition. With each method, we utilized moist and lyophilized feces. The validation of radioimmunoassay method was accurate and precise for quantify estradiol and progesterone in lyophilized feces of A. pigra. To both of which ethanol and methanol, absolute and at 80%, were added, besides the hormones (125)I-Estradiol and (125)I-Progesterone. The extraction efficiency for (125)I-Estradiol was from 87.72 ± 3.97 to 41.24 ± 2.67%, and for (125)I-Progesterone from 71.15 ± 4.24 to 42.30 ± 1.19% when we used the agitation method. Whereas with the ebullition method, the extraction efficiency for (125)I-Estradiol ranged from 86.89 ± 2.66 to 71.68 ± 3.02% and for (125)I-Progesterone from 98.31 ± 1.26 to 85.40 ± 1.98%. Due to the differences found in these assays, which depend on the method used, the type of feces employed and the type of solvent added to them, we recommend the ebullition method and the lyophilized feces of A. pigra for extracting the hormones, since in moist feces there may exist variables which might interfere in the quantification of (125)I-Estradiol and (125)I-Progesterone.

Relationships between physiological characteristics and trace metal body burdens of banded garden spiders Argiope trifasciata (Araneae, Araneidae)

Banded garden spiders (Argiope trifasciata) were collected at the Ballona Wetlands, a metal contaminated salt marsh. The relationship between spider body size and individual metal loads was investigated. Biochemical markers were identified in spider fecal material and found to correlate to body metal levels. Body metal dry weight concentrations of Cd, Cr, Cu, Zn and total metals in female A. trifasciata exhibited distinct patterns of spatial and annual variation during 2006 and 2007. Spider body size was homogeneous across sites in both years, while increased Cd and Cr concentrations were sometimes associated with a reduction in spider size, though the influence of Cr was quite minor. Spiders with higher body Cu levels showed a reduction in peak area for hypoxanthine and an un-identified component in fecal material chromatograms. Spatial and annual differences in metal bioaccumulation are likely mediated by variation in site-specific environmental parameters and rainfall, while the negative relationships between body size and metal levels are presumably a consequence of a spider's expenditure of energy for metal tolerance mechanisms vs. foraging and growth. Finally, correlating body metal levels with excreta products constitutes a novel method to non-invasively predict metal levels in spiders.

Does environmental enrichment reduce stress? An integrated measure of corticosterone from feathers provides a novel perspective

Enrichment is widely used as tool for managing fearfulness, undesirable behaviors, and stress in captive animals, and for studying exploration and personality. Inconsistencies in previous studies of physiological and behavioral responses to enrichment led us to hypothesize that enrichment and its removal are stressful environmental changes to which the hormone corticosterone and fearfulness, activity, and exploration behaviors ought to be sensitive. We conducted two experiments with a captive population of wild-caught Clark's nutcrackers (Nucifraga columbiana) to assess responses to short- (10-d) and long-term (3-mo) enrichment, their removal, and the influence of novelty, within the same animal. Variation in an integrated measure of corticosterone from feathers, combined with video recordings of behaviors, suggests that how individuals perceive enrichment and its removal depends on the duration of exposure. Short- and long-term enrichment elicited different physiological responses, with the former acting as a stressor and birds exhibiting acclimation to the latter. Non-novel enrichment evoked the strongest corticosterone responses of all the treatments, suggesting that the second exposure to the same objects acted as a physiological cue, and that acclimation was overridden by negative past experience. Birds showed weak behavioral responses that were not related to corticosterone. By demonstrating that an integrated measure of glucocorticoid physiology varies significantly with changes to enrichment in the absence of agonistic interactions, our study sheds light on potential mechanisms driving physiological and behavioral responses to environmental change.

Measuring stress in wildlife: techniques for quantifying glucocorticoids

Stress responses play a key role in allowing animals to cope with change and challenge in the face of both environmental certainty and uncertainty. Measurement of glucocorticoid levels, key elements in the neuroendocrine stress axis, can give insight into an animal's well-being and can aid understanding ecological and evolutionary processes as well as conservation and management issues. We give an overview of the four main biological samples that have been utilized [blood, saliva, excreta (feces and urine), and integumentary structures (hair and feathers)], their advantages and disadvantages for use with wildlife, and some of the background and pitfalls that users must consider in interpreting their results. The matrix of choice will depend on the nature of the study and of the species, on whether one is examining the impact of acute versus chronic stressors, and on the degree of invasiveness that is possible or desirable. In some cases, more than one matrix can be measured to achieve the same ends. All require a significant degree of expertise, sometimes in obtaining the sample and always in extracting and analyzing the glucocorticoid or its metabolites. Glucocorticoid measurement is proving to be a powerful integrator of environmental stressors and of an animal's condition.

Eliminating the artificial effect of sample mass on avian fecal hormone metabolite concentration

Avian endocrinology is a productive field that could benefit from increased application of non-invasive techniques. Although assay protocols vary, most studies that measure hormone metabolites in avian feces struggle with an artificial effect of sample mass on steroid metabolite concentration. Hormone metabolite concentrations measured in small samples are consistently higher than concentrations in larger samples, and this appears to be due to multiple methodological problems. We systematically tested several causal hypotheses for the mass effect. Based on results from these tests, we modified and validated our assay protocol to effectively eliminate the mass effect. Future studies should implement the following procedures when measuring hormone metabolites from small fecal samples (particularly of birds and reptiles): (1) remove urates from the fecal sample as completely as possible; (2) lyophilize the sample prior to extraction; (3) maximize accuracy of small mass measurements; (4) increase the volume of ethanol in the extraction to 15 ml per 0.05-0.1g of dried feces; and (5) eliminate ethanol from all samples prior to radioimmunoassay by drying down extract solutions and rehydrating in buffer. By applying these precautions we successfully eliminated the mass effect from fecal samples ranging in mass from 0.001 to 0.1 g using a radioimmunoassay commonly employed for studies of fecal glucocorticoid metabolites. These corrections also resulted in a more than 3-fold increase in effect size in glucocorticoid concentrations from a controlled test of the effects of 1h motorcycle exposure on northern spotted owls. These methods have important implications not only for avian studies, but for any study measuring hormone metabolites from small fecal samples.

The adrenocortical response of greater sage grouse (Centrocercus urophasianus) to capture, ACTH injection, and confinement, as measured in fecal samples

Investigators of wildlife populations often utilize demographic indicators to understand the relationship between habitat characteristics and population viability. Assessments of corticosterone may enable earlier detection of populations at risk of decline because physiological adjustments to habitat disturbance occur before reproductive diminutions. Noninvasive methods to accomplish these assessments are important in species of concern, such as the greater sage grouse (GRSG). Therefore, we validated a radioimmunoassay that measures immunoreactive corticosterone metabolites (ICM) in fecal samples and used it to characterize the adrenocortical response of 15 GRSG exposed to capture, intravenous injection of 50 IU/kg adrenocorticotrophic hormone (ACTH) or saline, and 22 h of confinement. Those animals injected with ACTH exhibited a more sustained (P = 0.0139) and less variable (P = 0.0012) response than those injected with saline, indicating different levels of adrenocortical activity. We also found that potential field-collection protocols of fecal samples did not alter ICM concentrations: samples held at 4 degrees C for up to 16 h contained similar levels of ICM as those frozen (-20 degrees C) immediately. This study demonstrates a multiphasic adrenocortical response that varied with the level of stimulation and indicates that the assay used to measure this phenomenon is applicable for studies of wild GRSG.

Fecal glucocorticoid metabolites of experimentally stressed captive and free-living starlings: implications for conservation research

Fecal glucocorticoid metabolite (FGM) analysis has received considerable attention in conservation biology because it has potential to be used as a noninvasive measure of stress in animals. There has been a recent and extensive literature describing the importance of technical, physiological, and biological validations of this technique, yet surprisingly little is known about how FGM concentrations change during chronic stress. Therefore, we experimentally induced chronic stress in both captive and free-living European starlings (Sturnus vulgaris). Chronic stress was elicited using a rotation of four different 30 min acute stressors for 16 days in the laboratory and 8 days in the field. Exogenous ACTH, the primary glucocorticoid secretagog, significantly increased FGM concentrations in approximately 2 h, and our assay detected endogenous diel glucocorticoid rhythms similar to those of other birds. Thus, our assay was both physiologically and biologically validated. However, experimentally induced chronic stress did not alter daytime or nighttime FGM concentrations in captive starlings. In contrast, chronically stressed adult female starlings had higher FGM concentrations than unstressed female starlings in the field. Our field data support the general assumption that higher FGM concentrations indicate chronic stress, but our captive data do not. Overall, our results suggest that more research is need before FGM analysis can be used as a reliable measure of stress in animals, especially those kept in captivity.

Fecal steroid monitoring for assessing gonadal and adrenal activity in the golden eagle and peregrine falcon

We examined the efficacy of noninvasive monitoring of endocrine function via fecal steroid immunoassays in the golden eagle and peregrine falcon. High-pressure liquid chromatography analyses of fecal glucocorticoid metabolites (fGCM) revealed that minor percentages of immunoreactive fGCM co-eluted with [(3)H]corticosterone in both sexes of the eagle (2.5-2.7%) and falcon (7.5-11.9%). In contrast, most fecal estrogen metabolites in eagle and falcon females co-eluted with radiolabeled estradiol-17beta ([(3)H]; 57.6, 64.6%, respectively) or estrone ([(3)H]; 26.9, 4.1%, respectively). Most fecal progestin metabolite immunoreactivity in the female eagle (24.8%) and falcon (21.7%) co-eluted with progesterone ([(14)C]). Most fecal androgen metabolite immunoreactivity in eagle (55.8%) and falcon (63.7%) males co-eluted with testosterone ([(14)C]). Exogenous adrenocorticotropin hormone induced increased fGCM excretion above pre-treatment in both species, but only significantly (P < 0.05) in the eagle. Both species showed increased fGCM after saline administration, suggesting the detection of 'handling stress.' Both species exhibited enterohepatic and renal recirculation of administered steroids as demonstrated by biphasic and triphasic excretion patterns. Thus, noninvasive fecal hormone monitoring is a valid and promising tool for assessing gonadal and adrenal status in rare and threatened birds-of-prey.

Low ambient temperature increases food intake and dropping production, leading to incorrect estimates of hormone metabolite concentrations in European stonechats

Non-invasive methods to measure steroid hormone metabolites in bird droppings or mammalian feces have become very popular. However, the accuracy of these measurements may be affected by many factors. Here, we use the stonechat (Saxicola torquata) as a passerine bird model to test whether differences in ambient temperature affect food intake and dropping production and whether these changes lead to measurement artefacts in hormone metabolite concentrations. In addition, we tested for diurnal patterns in hormone metabolites. We held European stonechats in climate chambers and subjected them to two different long-term ambient temperature regimes, +5 degrees C and +22 degrees C. As expected, food intake and dropping production was higher at +5 degrees C than at +22 degrees C. Plasma concentrations of corticosterone and testosterone did not differ between different ambient temperature regimes. However, corticosterone and testosterone metabolite concentrations (in ng/g) were significantly lower at +5 degrees C than at +22 degrees C. When we measured the rate of hormone metabolite excretion (in picogram per hour) instead of the concentration, there was no difference between treatment groups. Thus, the measurement of hormone metabolite concentrations can be flawed because, depending on the treatment, similar amounts of hormone metabolites can be excreted into very different amounts of droppings. In conclusion, hormone metabolite concentration measurements are sensitive to changes in ambient temperature and probably any other factor that alters metabolic rates. Any study involving systematic changes in metabolism--i.e., during molt, migration, hibernation, egg production, or seasonal comparisons--needs to take these caveats into account.

Measuring fecal steroids: guidelines for practical application

During the past 20 years, measuring steroid hormone metabolites in fecal samples has become a widely appreciated technique, because it has proved to be a powerful, noninvasive tool that provides important information about an animal's endocrine status (adrenocortical activity and reproductive status). However, although sampling is relatively easy to perform and free of feedback, a careful consideration of various factors is necessary to achieve proper results that lead to sound conclusions. This article aims to provide guidelines for an adequate application of these techniques. It is meant as a checklist that addresses the main topics of concern, such as sample collection and storage, time delay extraction procedures, assay selection and validation, biological relevance, and some confounding factors. These issues are discussed briefly here and in more detail in other recent articles.