The effect of pre‐release captivity on the stress physiology of a reintroduced population of wild eastern bettongs

Biological validation of faecal corticosterone metabolites as a non-invasive stress assessment in translocated California valley quail (Callipepla californica)

US quail species are vulnerable to population declines as a result of climate change, habitat loss and habitat fragmentation, all of which can result in physiological stress. Additionally, population restoration techniques (PRTs), like translocations, also induce stress. Traditional assessments of avian stress hormone levels include capturing and handling birds to extract blood, methods that are inherently stressful and can compound stress analyses. However, the stress hormone corticosterone (CORT) is metabolized from the blood and excreted in faeces as faecal corticosterone metabolites (FCMs). FCMs have been used as a non-invasive measurement of stress hormone levels in a variety of species, but must be validated for each species. The objective of this study was to biologically validate the use of FCMs as a non-invasive measurement of CORT levels in California valley quail (Callipepla californica). Reference and treatment quail were acclimated for 3 weeks in an outdoor aviary. Subsequently, treatment quail were subjected to a simulated 48-h translocation, a common and stress hormone-inducing PRT. Faecal samples were collected every 4 h and processed using an enzyme immunoassay. Mean FCM concentrations of treatment quail (41.50 ± 16.13 ng/g) were higher than reference FCM concentrations (24.07 ± 10.4 ng/g). These results biologically validate the use of FCMs as a non-invasive method to assess CORT levels in California valley quail, demonstrate diurnal variation in quail CORT levels, and confirm that quail translocations are a stress-inducing PRT. Ultimately, this research validates a new non-invasive tool for stress response measurement to advance quail research, management and conservation.

Review of hyperdispersal in wildlife translocations

Species translocation is a common tool to reverse biodiversity loss, but it has a high failure rate. One factor that contributes to failure is postrelease hyperdispersal, which we define as the long-distance movement of individuals resulting in their failure to contribute to population establishment. We reviewed reported incidences of hyperdispersal and compared rates of hyperdispersal among taxa, population demographics, release cohorts, and success of mitigation techniques. Of 151 conservation translocations (reinforcements and reintroductions) in which animals were tracked, hyperdispersal was confirmed in 52.1% of programs. The prevalence of hyperdispersal (percentage of studies) was relatively consistent across taxa (42.9-60%), but hyperdispersal rates in birds were likely underestimated because 76.9% of bird translocations showed incidences in which birds could not be located after release, but hyperdispersal was unable to be confirmed. Eutherians exhibited a higher average incidence of hyperdispersal (percentage of hyperdispersing individuals in a cohort) of 20.2% than birds, reptiles, and marsupials (10.4%, 15.7%, and 10.3%, respectively). No significant trends were observed for sex, source population, or translocation type, but there were nonsignificant trends for males to hyperdisperse more than females and for higher incidences of hyperdispersal in reinforcements relative to reintroduction programs. Mitigation techniques included temporary confinement, supplementation of resources, and releasing animals in social groups, but only half of studies examining mitigation techniques found them useful. Hyperdispersal incidence was variable within taxa, and we advise against forming translocations strategies based on results from other species. Hyperdispersal is a significant welfare, economic, and conservation issue in translocations, and we suggest definitions, reporting, and experimental strategies to address it.

Return to 1616: Multispecies Fauna Reconstruction Requires Thinking Outside the Box

Conservation translocations have become increasingly popular for 'rewilding' areas that have lost their native fauna. These multispecies translocations are complex and need to consider the requirements of each individual species as well as the influence of likely interactions among them. The Dirk Hartog Island National Park Ecological Restoration Project, Return to 1616, aspires to restore ecological function to Western Australia's largest island. Since 2012, pest animals have been eradicated, and conservation translocations of seven fauna species have been undertaken, with a further six planned. Here, we present a synthesis of the innovative approaches undertaken in restoring the former faunal assemblage of Dirk Hartog Island and the key learnings gathered as the project has progressed.

Assessing stress physiology within a conservation breeding program for an endangered species

Conservation breeding programs typically involve the management of individuals both in and ex situ, so it is vital to understand how the physiology of managed species changes in these environments to maximize program outcomes. The Vancouver Island marmot (VIM; Marmota vancouverensis) is one species that has been managed in a conservation breeding program to recover the critically low wild population. Previous research has shown there are differences in hair glucocorticoid concentrations for VIMs in different managed groups in the program. Therefore, we used >1000 blood samples collected since the program's inception to assess the neutrophil to lymphocyte (N:L) ratio among captive, pre-release, post-release and wild populations as another metric of stress. In situ VIM populations were found to have a significantly higher N:L ratio than ex situ populations, suggesting that the wild is a more physiologically challenging environment than managed care. Moreover, the effect of age, sex and the month of sampling on the N:L ratio were found to be different for each population. Age had the greatest magnitude of effect in the wild population, and sex was only significant in ex situ populations. This study provided previously unknown insights into the physiology of VIMs and increased post-release monitoring will be useful in the future to fully understand how physiology may be contributing to differences in survival of VIMs in the program.

Successful acclimatization of mandrills (Mandrillus sphinx) translocated to Conkouati-Douli National Park, Republic of Congo, as measured by fecal glucocorticoid metabolites

Translocation and reintroduction are common tools in conservation management and can be very successful. However, translocation can be stressful for the animals involved, and stress is implicated as a major cause of failure in release programs. Conservation managers should therefore seek to understand how the stages of translocation impact stress physiology in the animals involved. We quantified fecal glucocorticoid metabolites (fGCMs) as a noninvasive measure of response to potential stressors during a translocation of 15 mandrills (Mandrillus sphinx) into Conkouati-Douli National Park, Republic of Congo. The mandrills were initially housed in a sanctuary, transferred to a pre-release enclosure in the National Park and then released into the forest. We collected repeated fecal samples (n = 1101) from known individuals and quantified fGCMs using a previously validated enzyme immunoassay. Transfer from the sanctuary to the pre-release enclosure correlated with a significant 1.93-fold increase in fGCMs, suggesting that transfer was a stressor for the mandrills. fGCM values decreased over time in the pre-release enclosure, suggesting that the mandrills recovered from the transfer and acclimatized to the enclosure. Release to the forest was not linked to a significant increase in fGCMs over the final values in the enclosure. Following release, fGCMs continued to decrease, fell below sanctuary values after just over a month and were about half the sanctuary values after 1 year. Overall, our results suggest that the translocation, although initially presenting a physiological challenge to the animals, was not detrimental to the well-being of the animals over the timescale of the study and, in fact, may have been beneficial. Our findings show the value of non-invasive physiology in monitoring, evaluating and designing wildlife translocations and, ultimately, contributing to their success.

Captivity and Animal Microbiomes: Potential Roles of Microbiota for Influencing Animal Conservation

During the ongoing biodiversity crisis, captive conservation and breeding programs offer a refuge for species to persist and provide source populations for reintroduction efforts. Unfortunately, captive animals are at a higher disease risk and reintroduction efforts remain largely unsuccessful. One potential factor in these outcomes is the host microbiota which includes a large diversity and abundance of bacteria, fungi, and viruses that play an essential role in host physiology. Relative to wild populations, the generalized pattern of gut and skin microbiomes in captivity are reduced alpha diversity and they exhibit a significant shift in community composition and/or structure which often correlates with various physiological maladies. Many conditions of captivity (antibiotic exposure, altered diet composition, homogenous environment, increased stress, and altered intraspecific interactions) likely lead to changes in the host-associated microbiome. To minimize the problems arising from captivity, efforts can be taken to manipulate microbial diversity and composition to be comparable with wild populations through methods such as increasing dietary diversity, exposure to natural environmental reservoirs, or probiotics. For individuals destined for reintroduction, these strategies can prime the microbiota to buffer against novel pathogens and changes in diet and improve reintroduction success. The microbiome is a critical component of animal physiology and its role in species conservation should be expanded and included in the repertoire of future management practices.

Adapting reintroduction tactics in successive trials increases the likelihood of establishment for an endangered carnivore in a fenced sanctuary

Threatened species recovery programs are increasingly turning to reintroductions to reverse biodiversity loss. Here we present a real-world example where tactics (techniques which influence post-release performance and persistence) and an adaptive management framework (which incorporates feedback between monitoring and future actions) improved reintroduction success. Across three successive trials we investigated the influence of tactics on the effective survival and post-release dispersal of endangered eastern quolls (Dasyurus viverrinus) reintroduced into Mulligans Flat Woodland Sanctuary, Australian Capital Territory. Founders were monitored for 42 days post-release, and probability of survival and post-release dispersal were tested against trial, origin, sex, den sharing and presence of pouch young. We adopted an adaptive management framework, using monitoring to facilitate rapid learning and to implement interventions that improved reintroduction success. Founders released in the first trial were less likely to survive (28.6%, n = 14) than those founders released the second (76.9%, n = 13) and third trials (87.5%, n = 8). We adapted several tactics in the second and third trials, including the selection of female-only founders to avoid elevated male mortality, and post-mating releases to reduce stress. Founders that moved dens between consecutive nights were less likely to survive, suggesting that minimising post-release dispersal can increase the probability of survival. The probability of moving dens was lower in the second and third trials, for females, and when den sharing with another founder. This study demonstrates that, through iterative trials of tactics involving monitoring and learning, adaptive management can be used to significantly improve the success of reintroduction programs.

BASELINE HEALTH AND DISEASE ASSESSMENT OF FOUNDER EASTERN QUOLLS (DASYURUS VIVERRINUS) DURING A CONSERVATION TRANSLOCATION TO MAINLAND AUSTRALIA

We evaluated the health of 31 (eight males, 23 females) founder eastern quolls (Dasyurus viverrinus), translocated to a fenced reserve in the Australian Capital Territory between February 2016 and July 2017. Quolls were wild caught in Tasmania (16 animals) or captive bred at Mount Rothwell Biodiversity Interpretation Centre, Victoria (15 animals). Quolls were assessed for the presence of selected potential pathogens (Toxoplasma gondii, herpesviruses, Salmonella serovars, hemoprotozoa, and ectoparasites). We assessed the relationships among sex, provenance (captive or free ranging), T. gondii or herpesvirus infection, weight, and hematologic and biochemical variables. Six of 21 quolls (29%) tested were seropositive for antibodies to T. gondii. Seropositive quolls weighed significantly more and had significantly lower potassium levels, anion gaps, and urea and triglyceride levels than seronegative quolls had. Eighteen of 31 (58%) combined conjunctival-pharyngeal-cloacal swabs collected from quolls were PCR positive for a newly identified gammaherpesvirus, tentatively named dasyurid gammaherpesvirus 3. There were no significant differences among hematologic and biochemical variables or body weights from PCR-positive and PCR-negative quolls. Eighteen of 18 (100%) of rectal-swab samples were culture negative for Salmonella serovars. Three species of tick (Ixodes tasmani, Ixodes fecialis, and Ixodes holocyclus), two species of mite (Andreacus radfordi, one unidentified), and four species of flea (Pygiopsylla hoplia, Acanthopsylla rothschildi rothschildi, Uropsylla tasmanica, and Stephanocircus dasyuri), were detected on wild-caught quolls, whereas a fifth species of flea, Echidnophaga myremecobii, was detected only on captive-bred quolls. Five of 15 blood samples (33%) were positive for hemoprotozoan DNA via PCR, a novel Hepatozoon species, a novel Theileria species, Theileria paparinii, and Trypanosoma copemani were detected. Despite the presence of several potential pathogens known to be associated with disease in other marsupials, the quolls were considered to be in good general health, suitable for translocation, and a viable population was subsequently established.

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.

Effects of handling and short-term captivity: a multi-behaviour approach using red sea urchins, Mesocentrotus franciscanus

Understanding the effects of captivity-induced stress on wild-caught animals after their release back into the wild is critical for the long-term success of relocation and reintroduction programs. To date, most of the research on captivity stress has focused on vertebrates, with far less attention paid to invertebrates. Here, we examine the effect of short-term captivity (i.e., up to four days) on self-righting, aggregation, and predator-escape behaviours in wild-caught red sea urchins, Mesocentrotus franciscanus, after their release back into the wild. Aggregation behaviour, which has been linked to feeding in sea urchins, was not affected by handling or captivity. In contrast, the sea urchins that had been handled and released immediately, as well as those that were handled and held captive, took longer to right themselves and were poorer at fleeing from predators than wild, unhandled sea urchins. These results indicate that handling rather than captivity impaired these behaviours in the short term. The duration of captivity did not influence the sea urchin behaviours examined. Longer-term monitoring is needed to establish what the fitness consequences of these short-term behavioural changes might be. Our study nevertheless highlights the importance of considering a suite of responses when examining the effects of capture and captivity. Our findings, which are based on a locally abundant species, can inform translocation efforts aimed at bolstering populations of ecologically similar but depleted invertebrate species to retain or restore important ecosystem functions.

Chronic captivity stress in wild animals is highly species-specific

Wild animals are brought into captivity for many reasons-conservation, research, agriculture and the exotic pet trade. While the physical needs of animals are met in captivity, the conditions of confinement and exposure to humans can result in physiological stress. The stress response consists of the suite of hormonal and physiological reactions to help an animal survive potentially harmful stimuli. The adrenomedullary response results in increased heart rate and muscle tone (among other effects); elevated glucocorticoid (GC) hormones help to direct resources towards immediate survival. While these responses are adaptive, overexposure to stress can cause physiological problems, such as weight loss, changes to the immune system and decreased reproductive capacity. Many people who work with wild animals in captivity assume that they will eventually adjust to their new circumstances. However, captivity may have long-term or permanent impacts on physiology if the stress response is chronically activated. We reviewed the literature on the effects of introduction to captivity in wild-caught individuals on the physiological systems impacted by stress, particularly weight changes, GC regulation, adrenomedullary regulation and the immune and reproductive systems. This paper did not review studies on captive-born animals. Adjustment to captivity has been reported for some physiological systems in some species. However, for many species, permanent alterations to physiology may occur with captivity. For example, captive animals may have elevated GCs and/or reduced reproductive capacity compared to free-living animals even after months in captivity. Full adjustment to captivity may occur only in some species, and may be dependent on time of year or other variables. We discuss some of the methods that can be used to reduce chronic captivity stress.