American Zoos Research Articles

Inactivated Toxoplasma gondii nanovaccine boosts T-cell memory response in a seropositive Yellow-footed rock wallaby (Petrogale xanthopus) – a case report from Copenhagen Zoo

Toxoplasma gondii is a ubiquitous parasite causing significant mortality in captive wildlife, especially marsupials. Historically, treatment has been unrewarding and no vaccine was available. An intranasal vaccine based on purified inactivated T. gondii was developed for toxoplasmosis prevention. A vaccination campaign started in early 2017 and was successful in preventing toxoplasma-related mortality in marsupials in many European and South American zoos. Amongst the vaccinated wallabies, about 30% were T. gondii seropositive before the vaccination, and no toxoplasma-related deaths were observed since the administration of the vaccine. The objective of this case study was to assess the potential effect of the vaccination on a seropositive wallaby. It is important to note that this vaccine doesn’t induce any humoral response in sheep, and squirrel monkeys but induces a strong T-cell response. A T. gondii seropositive Yellow-footed rock wallaby (Petrogale xanthopus) from Copenhagen Zoo received two doses of the aforementioned intranasal vaccine. Blood samples were collected before each vaccination and used for peripheral blood mononuclear cell isolation. The impact of the vaccination on the lymphocyte phenotype was characterized by flow cytometry. Cell size, represented by forward scatter, and granularity, represented by side scatter parameters were analyzed. Two doses of the vaccine induced a respective 30.1 and 25.6% increase in cell size and granularity in lymphocytes stimulated with T. gondii antigens, as assessed by flow cytometry. These changes were likely correlated with T-cell activation, which indicates that two doses of the vaccine might have boosted the already-existing T-cell memory response against T. gondii in a seropositive animal. No morphological changes were observed in lymphocytes from an unvaccinated seronegative wallaby. This is the first documented case of boosting an already-existing cellular immune response against toxoplasmosis by the vaccine in a seropositive Yellow-footed rock wallaby.

SARS-CoV-2 morbidity, treatment interventions, and vaccination practices in tigers (Panthera tigris ssp) in North American zoos.

Evaluate SARS-CoV-2 morbidity, mortality, clinical signs, treatment interventions, and vaccination practices in tigers under professional care. Amur (Panthera tigris altaica), Sumatran (Panthera tigris sumatrae), and Malayan (Panthera tigris jacksoni) tigers managed under the Tiger Species Survival Plan (SSP). A retrospective, voluntary online survey was sent to all North American zoos holding SSP tigers between January 2020 and June 2023. Responses were received from 55 of 108 institutions (51%) housing 162 tigers in total, and SARS-CoV-2 infection was diagnosed in 39 tigers from 15 institutions (20 Amur, 8 Sumatran, and 11 Malayan [1 to 18 years old; 17 males and 22 females]). This corresponds to a minimum study group infection incidence of 24% over 42 months. Clinical signs included dry cough (82%), inappetence (64%), lethargy (62%), nasal discharge (46%), wheezing (31%), wet cough (18%), and ocular discharge (15%). Most cases were characterized as mild (n = 22) or moderate (14). A single case was characterized as severe. Two cases were asymptomatic. Seventeen positive tigers had been vaccinated once (n = 8) or twice (9) for SARS-CoV-2 prior to infection. No deaths due to SARS-CoV-2 were reported in the study group. Treatment interventions included antibiotics (49%), NSAIDs (18%), antiemetics (15%), and fluids (13%). No treatments were administered in 19 of 39 cases (49%). Amongst participating institutions, 69% reported fully vaccinating tigers for SARS-CoV-2 (≥ 2 doses). Most SARS-CoV-2-infected tigers presented with mild to moderate clinical signs and recovered with limited to no treatment interventions. Asymptomatic SARS-CoV-2 infections can occur in tigers and may be underreported. Tigers vaccinated for SARS-CoV-2 remain susceptible to infection.

Nursing Behavior of Bottlenose Dolphin (Tursiops truncatus) Calves from 1990-2014 at Brookfield Zoo Chicago, USA

While the common bottlenose dolphin (Tursiops truncatus) population under managed care in North American zoos and aquariums is self-sustaining, understanding normal nursing behavior can help management make informed care decisions for neonates and future births. This study examined behavioral data from the first 30 days of life collected from 14 dolphin calves born between 1990-2014 at Brookfield Zoo Chicago in Brookfield, IL. We hypothesized that surviving calves showed significantly different patterns of nursing than those that did not survive. There were no significant differences in average nursing rates or average nursing frequency between calves that did and did not survive up to 17 days old. Surviving calves up to eight days old had significantly longer average nursing performance (s/hr), and significantly longer average nursing durations (s/bout) than non-surviving calves. Shorter nursing duration early in the life of the calf may be indicative of developmental problems and may be a useful metric to inform staff when supplemental care may be needed. Calf survival improved from the first half to the second half of the study period by 150%, most likely due to improvements in animal care, medical intervention, and experience of the dams. Understanding normal nursing behavior is essential to learning when human intervention is necessary to help survival and can help guide future care and management of dolphin births under professional care.

PROSPECTIVE POSTMORTEM ASSESSMENT OF THE INCIDENCE OF MAMMARY NEOPLASIA IN CHIMPANZEES (PAN TROGLODYTES).

When evaluating the last 25 yr of morbidity and mortality from adult chimpanzees managed within the Association of Zoo and Aquarium Chimpanzee Species Survival Plan® for North American zoos, only two female chimpanzees were diagnosed with mammary neoplasia: one incidentally antemortem and one with a terminal metastatic neoplasia. When comparing this observation of prevalence of mammary neoplasia to humans, a substantial disparity is apparent. Mammary neoplasia is the second most common cancer in adult female humans, with a lifetime risk of 1:8 in the United States. The reason for the disparity between humans and chimpanzees, as closely related species, is unknown. The true prevalence in chimpanzees may be higher than currently noted, because routine examination of mammary tissue in chimpanzees is generally less complete than for other tissues postmortem, and antemortem assessment is generally limited to mammary palpation. This study was performed on intact, bilateral mammary glands harvested at postmortem examination of adult female chimpanzees (n = 7) from six institutions. With mammography, complete histopathologic sectioning, and genetic evaluation, the risk of mammary neoplasia was evaluated more thoroughly than during a typical postmortem exam in zoo populations during 2017-2019. No chimpanzees in the study were diagnosed with mammary neoplasia. Overall, this study supports the previous impression that chimpanzees do not develop mammary neoplasia at a similar rate as humans, even when comparable diagnostic modalities for evaluation are used.

Geckos in zoos: A global approach on distribution patterns of threatened geckos (Gekkota) in zoological institutions

According to the One Plan Approach to Conservation, proposed by the IUCN SSC Conservation Planning Specialist Group (CPSG), there is, besides in situ conservation measures, also increased need for ex situ conservation breeding of threatened taxa. To gain a better overview of the current situation, we have compiled information from the zoo databases ZIMS (Zoological Information Management System) and ZTL (Zootierliste) on the husbandry of gecko species (suborder Gekkota) worldwide. Only 9.3 % (n = 201) of the 2151 currently recognized gecko species from seven families were kept according to ZIMS, of which about 20.4 % (n = 41) were classified as threatened. Most species were kept in European, North American and Australian zoos. Many of the species were kept outside the natural distributional range hotspots of geckos. However, institutions in Oceania kept mainly native geckos. The species richness of the natural distributional ranges of zoo-kept geckos was highest in Australia, Southeast Asia, Madagascar and lowest in South America. About 38.0 % (n = 25) of zoo-kept species with a successful breeding record were threatened, and most reproductive successes of threatened species have been recorded from only one institution per species. Although Gekkota is the most species-rich group among lizards (Sauria), they are still relatively poorly represented in zoological institutions, and most of the kept species are not threatened. Zoos inside and outside the distributional range can play a key role in conservation (breeding) programs, when they continue to provide their expertise and resources for the buildup of insurance colonies for threatened taxa. Preferably this is carried out in cooperation with experts and conservation centers from the species’ range countries and also in cooperation with Citizen Conservation programs.

Genomic resources for Asian (Elephas maximus) and African savannah elephant (Loxodonta africana) conservation and health research.

We provide novel genomic resources to help understand the genomic traits involved in elephant health and to aid conservation efforts. We sequence 11 elephant genomes (5 African savannah, 6 Asian) from North American zoos, including 9 de novo assemblies. We estimate elephant germline mutation rates and reconstruct demographic histories. Finally, we provide an in-solution capture assay to genotype Asian elephants. This assay is suitable for analyzing degraded museum and noninvasive samples, such as feces and hair. The elephant genomic resources we present here should allow for more detailed and uniform studies in the future to aid elephant conservation efforts and disease research.

Abnormal prolactin secretion is associated with changes in metabolic health biomarkers in acyclic female African elephants (Loxodonta africana)

Circulating prolactin aberrations (chronically high or low concentrations) have been shown to have strong associations with ovarian dysfunction in African female elephants. However, despite the well-established pleiotropic role that prolactin plays in human health, comprehensive metabolic effects from chronically elevated or suppressed prolactin have yet to be investigated in this species. In humans, in addition to amenorrhea, hyperprolactinemic women have shown increased risks for accelerated atherosclerosis, hyperandrogenemia, lowered metabolism, and insulin resistance. The aim of the study was to determine if elephants with long-term abnormal prolactin secretion were also experiencing alterations in metabolic biomarkers. One year of serum samples, collected biweekly, were obtained from female African elephants (n = 74) housed in North American zoos and categorized based on ovarian cyclicity and prolactin status: normal cycling, normal prolactin (NORMAL, n = 25), acyclic, high prolactin (HIGH, n = 25), or acyclic, low prolactin (LOW, n = 24). Each sample was further analyzed for measures of metabolic function, glucose metabolism, and cardiovascular health. Overall, thyroid hormones were significantly lower in both HIGH (TSH, T3, T4) and LOW (TSH) prolactin elephants compared to NORMAL counterparts. Additionally, HIGH prolactin elephants exhibited lower glucose, G:I ratios, and low-density lipoprotein values, but higher cholesterol concentrations compared to normal cycling females. Overall, LOW prolactin elephants exhibited higher body condition scores and G:I ratios, and higher concentrations of insulin, high-density lipoproteins, cortisol and testosterone, but decreased triglyceride values compared to NORMAL elephants in the study. Data suggest that HIGH prolactin elephants may be experiencing hypothyroidism as a comorbidity, whereas LOW prolactin elephants may be exhibiting aspects of insulin resistance, albeit different from human clinical data. Specific studies are suggested that would help elucidate the underlying mechanisms at play and increase our understanding of prolactin’s role in elephant physiology.

“I Don’t Need Your Help! I’m a Scientist!” Biotechnology, Digital Visual Effects, and (the Lack of) Human Control of Life in Zoo

This article explores the American television series Zoo (CBS, 2015–2017). The show’s convoluted narrative revolves around mutations that are put into motion by genetic engineering. These mutations first affect animals and later humans The article argues that the biotechnological control of life, which takes center stage narratively, is mirrored in the television show’s use of digital visual effects to create animals. More importantly, Zoo suggests that this control of life is nothing but an illusion, as the mutation quickly gets out of hand and leads to unexpected consequences. Thus, the television series reflects the Anthropocene condition, which is characterized by the emergence of humankind as a planetary force; however, the planetary effects of anthropogenic activities have been largely unwanted. While Zoo seems to expose these processes of our age, the article also stresses that as a television show, Zoo must reach a broad audience. Thus, the critique of human fantasies of planetary control are, somewhat paradoxically, accompanied by an anthropocentrism which arguably undermines the show’s ecological subtexts.

Examining the representation of locally threatened species in North American zoos

AbstractA perceived dissonance exists between the stated conservation mission of modern zoos and the composition of species in their care. A bias toward charismatic taxa over threatened ones has been demonstrated in several studies. However, these prior examinations have principally relied on species threat status derived from global lists, and threat status reported for species on national and subnational lists often differ from global assessments. It has been suggested that some globally non‐threatened species maintained in zoos might fulfill local conservation priorities. In this study, we compare local threat status and zoo population size for native bird, mammal, reptile and amphibian species in North American zoos to assess the representation of locally threatened taxa. We found that native locally threatened species were kept in North American zoos slightly less than would be expected by chance; however, of the species that were represented in zoos, those that were threatened in more of the subnational regions where they occurred averaged larger populations within zoos. This suggests that the direct contribution from zoo animals to the conservation of locally threatened species is relatively limited with respect to taxonomic coverage, but this contribution may be underestimated by strictly counting the threatened species kept in 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 challenge of assisted reproduction for conservation of wild felids - A reality check

Threats to the Earth's biodiversity are increasing exponentially, driven by human population growth and resource consumption. As many as one million wildlife species may disappear within the next few decades due to this human-induced extinction event. This represents our current reality and has profound implications for wildlife conservation. Within this context, application of assisted reproductive technology (ART) to conservation management is unlikely to mitigate broad-scale species loss, but for select species, such as wild cats, ART may determine if populations survive or disappear. In North American and European zoos, 20 of the world's 38 wild felid species are managed within structured breeding programs, but most are not sustainable with natural breeding alone. Zoo-based breeding programs are facing tenuous futures due to triage-based responses to this growing sustainability crisis. Theoretically, ART could benefit conservation management, but only by recognizing and addressing its present challenges. The application of ART to wildlife has been rarely successful, with only 62 mammal species (including 15 cat species) ever propagated by AI, and just 35 of these species (6 cats) reproduced following frozen semen AI. Even this most basic form of ART has a minimal impact on wildlife sustainability. The drivers of this deficit include lack of species-specific reproductive knowledge and limited access to animals for study, but also is exacerbated by a science-conservation disconnect that attempts to apply advanced reproductive technologies to species in which basic ART remains unproven. For a few felid species, these scientific challenges have been overcome and AI with frozen semen is becoming feasible as a practical management tool; for other felids, further research is needed. Non-scientific issues also impair our ability to use ART to implement global management plans. Political dysfunction, regulatory barriers and societal indifference create inertia that interferes with achieving meaningful progress in applying ART to wildlife. Collectively, these challenges may seem insurmountable but human resiliency is essential if we are to resolve these issues in a systematic manner. It will require expanding collaborative efforts substantially and intensifying efforts to conserve wildlife species that are literally running out of time. Our goal is to create a new reality that includes a sustainable future for wild felids and other imperiled wildlife species.

Zooscape ecology: a conceptual analysis of zoos and landscape ecology.

ContextZoos are a unique landscape with fascinating connections to the principles of landscape ecology. These ‘zooscapes’ have a focus on managing wild species.ObjectivesThis article examines the multiple scales of zoos as urban green spaces, exhibit landscapes, and resources for resilience. I identify that landscape ecology can inform zoo evolution and note how zoos may provide a novel research site for landscape ecology.MethodsI provide a brief history of American zoos and insight into lingering questions within zoos, including their representations of animals and humans. Additionally, I note conceptual overlap between zoo design/function and landscape ecology literature.ResultsZoos provide habitat for native species and valued cultural ecosystem services. Zoo exhibits developed a landscape focus as modern landscape ecology emerged in the 1980s. Patches, corridors, and matrices exist within a zoo, and these facilities have value for the genetic support of fragmented populations. Zoos’ strategies for disease management are increasingly relevant for global health. Simultaneously, zoos must exhibit sustainable landscapes, not just ecological simulacrums for threatened species.ConclusionsZoos must promote humanity’s continued coexistence with other species. A landscape view is essential to achieving this goal. Zoos need to model sustainable landscapes of our present and future.

Soft tissue sarcomas in 2 zoo-housed Alaskan moose.

Soft tissue sarcomas (STSs) are common well-described cutaneous neoplasms in many domestic species. Few cutaneous neoplasms have been reported in cervids, other than papilloma virus-induced benign cutaneous fibromas (BCFs). Two wild-caught Alaskan moose (Alces alces), housed at different North American zoos, were both presented with lameness and a mass. The gross appearance of each mass varied greatly; case 1 had a distinct, exophytic, ulcerated mass near the right carpal joint similar in appearance to a BCF, and case 2 had a pronounced swelling over the left hip. Based on histologic evaluation, both masses were diagnosed as STS. The clinical presentation of these masses included rapid growth and associated lameness; however, gross appearance was markedly different. Histopathology revealed characteristics typical of STS in other species, including spindle-shaped cells arranged in streaming sheets with ovoid nuclei. STS should be included as a differential diagnosis for moose with a cutaneous or subcutaneous soft tissue mass or swelling.

Social Behavior and Group Formation in Male Asian Elephants (Elephas maximus): The Effects of Age and Musth in Wild and Zoo-Housed Animals.

Simple SummaryThe conservation of wild and zoo-housed Asian elephants partly depends on developing our understanding of male elephant social behavior. Once thought to be solitary, we now know that male elephants can display rich social exchanges with both males and females. However, these interactions are expected to change with age and around the sexually active state of “musth.” We used behavioral data from wild and zoo-housed elephant populations to investigate how age, musth, and environmental factors influence how male elephants socialize and associate with group members. In Sri Lanka, only male elephants of older age (>20 years) exhibited signs of musth, but even some of the youngest zoo-housed elephants underwent musth (as young as 11 years). Additionally, we found that age and musth status predicted whether a wild male elephant associated with females, other males or was alone, as well as the number of conspecifics (males and females) in the same group with which a male was observed. Finally, rates of aggression, prosocial behavior (affiliative behaviors that promote positive social bonds between elephants), and submissive behavior exhibited by wild and zoo-housed male elephants were associated with age, musth status, the number of elephants presented, and group type (all-male or mixed sex). These results provide motivation for future studies of social behavior in male Asian elephants, as they will contribute to the reproduction and conservation of this endangered species.Asian elephants are endangered, and the long-term viability of the species depends on integrative approaches to address the sustainability of in-situ and ex-situ populations. Growing evidence shows that male elephants exhibit extensive and flexible social behavior that rivals the complexity of that of females. Male elephant sociality is expected to change dramatically around the unique sexual state of musth. However, data related to male Asian elephant sociality is lacking. Here, we conducted complementary observations in Wasgamuwa National Park, Sri Lanka, and North American zoos of male Asian elephant social behavior. Age and musth status, along with other factors, were associated with variation in social behavior and group formation of males. In wild male elephants, both musth status and age impacted elephant associations within all-male and mixed-sex groups: non-musth elephants were generally sighted less often in mixed-sex groups as they aged, while the inverse occurred with musth elephants. Musth status interacted with age to predict the number of conspecifics with which a wild male elephant associated: younger males were observed with more females during non-musth (but the opposite was true during musth), and male elephants between 20 and 30 years were observed with the highest number of male conspecifics except during musth. Finally, we found variation in aggression, prosocial behavior, and submissive behavior was influenced by intrinsic (age and musth status) and extrinsic factors (group size and type) in similar ways in both populations; prosocial behavior was most common and was influenced by the number of conspecifics present (both populations), and age, group type, and musth status (zoo population), while aggression was rare, especially among older elephants. We suggest that longitudinal studies of this threatened species will be particularly helpful to promote the reproduction and conservation of Asian elephants in in-situ and ex-situ environments.

Maximum longevity and juvenile mortality in zoo-housed mangabeys.

Little is known about the biology of grey-cheeked and black crested mangabeys (Lophocebus albigena and Lophocebus aterrimus, respectively). As these primates face threats in the wild, well-monitored zoo-housed populations with up to date registries are becoming increasingly valuable to acquire species knowledge and to support conservation efforts. We used international studbooks to extract demographic and genetic information on 519 mangabeys to investigate how life history and parent-related variables influence maximum longevity and juvenile mortality. Generalized linear mixed models, as well as survival analyses, were applied. Results showed that females lived significantly longer than males, which is not uncommon in primates. Furthermore, our results indicated that the maximum longevity is lower for individuals living in European zoos versus individuals from North American zoos, which may be due to a combination of environmental differences and potential founder effects. We also show that the maternal maximum longevity is positively related to the maximum longevity of the offspring, which may be explained by the inheritance of "good genes". However, the age of the mother at the moment of birth was negatively related to the maximum longevity of the offspring, which contradicts literature that states that, in primates, more experienced and thus older mothers will raise their offspring better than less experienced mothers. Instead, it is more likely that an "optimal age range" exists for breeding mothers. Our study provides insights into the population biology of captive mangabeys and may be helpful for identifying future research priorities to optimize primate health and welfare directly ex situ, and indirectly in situ.

Impacts of Socialization on Bull Asian Elephant (Elephas maximus) Stereotypical Behavior

There is a growing need for animal care institutions to house multiple bull elephants as the population increases due to transfers from private ownership and the births of male offspring in managed care. Elephants in North American, European, and Latin American zoos exhibit stereotypies—repetitive, fixed behaviors. Previous research demonstrated that housing Asian elephants alone increased stereotypic behavior. Therefore, for animals in managed care, social restriction can contribute to stereotypy and, by extension, reduce welfare. In this study, we examine how being alone affects stereotypic behavior by monitoring pacing and head-bobbing in individual bull Asian elephants at Denver Zoo when housed alone as well as with other bulls. Two young males arrived at Denver Zoo in September 2018 and joined an existing all-male group of three elephants that were previously socialized and housed together. From July 2018 to December 2019, we used instantaneous scan sampling to collect data on stereotypic behavior of focal bulls when they were housed alone and socially. The frequency of pacing and head-bobbing significantly decreased when the elephants were housed socially compared to when they were housed alone; these stereotypies were lower when elephants were housed with at least one other bull and were in close proximity to a conspecific. Additionally, pacing decreased as the proportion of affiliative behaviors increased, and the amount of agonistic behavior did not significantly affect stereotypic behavior. When housed alone, bulls in musth engaged in significantly more pacing behavior than when they were out of musth. Our results indicate that housing bull Asian elephants in all-male groups substantially improves their welfare by reducing stereotypies and provides a basis for future evidence-based management.

Survey of current group demographics and management practices of bachelor groups of western lowland gorillas (Gorilla gorilla gorilla) across North America.

Recommendations for the successful management and maintenance of bachelor groups of western lowland gorillas (Gorilla gorilla gorilla) in zoological settings have been an increasingly prevalent focus within the zoological community. Over the past two decades, studies have examined the impact of various environmental factors on the stability of bachelor groups, proposed management strategies for bachelor groups, and compared behavioral trends between bachelor and mixed-sex groups. These studies have clearly demonstrated that bachelor groups are complex social units that require specialized management approaches. In this study, we aimed to assess the extent to which bachelor group management across North American zoos accredited by the Association of Zoos and Aquariums aligns with established recommendations. We distributed a comprehensive survey broadly encompassing habitat and housing, aggression and wounding, group demographics, feeding, and training to the 22 zoos housing bachelor groups as of 2019. We received completed surveys from 19 zoos, representing a total of 21 social units and 59 individual gorillas. We used descriptive statistics to represent the range of current management strategies across the surveyed population and ANOVAs to assess significant variation in key demographic variables. Our results demonstrate that a majority of zoos have adopted the best practices for the formation of social groups established by Stoinski et al. in 2004. However, there is much less standardization across zoos in protocols surrounding training and feeding. Additionally, important variables in the assessment of wounding, such as time of day and location, are often unknown or not observed by animal care professionals. We highlight these two areas as being of particular focus in developing and adhering to consistent protocols across institutions.

The assessment of African penguin (Spheniscus demersus (Linnaeus, 1758)) management performances at the Underwater World Langkawi, Malaysia

A Malaysian Aquaria, the Underwater World Langkawi (UWL), has brought in 14 African penguins ( Spheniscus demersus ) for their ex-situ conservation. Following The Penguin Husbandry Manual produced by the American Zoo Aquarium Association (AZA), the UWL has adopted the population as their management regime and, as a result, has successfully bred the population from a total of 14 individuals to 40 individuals. This study aims to evaluate the captive management of penguins at the UWL and increase the efficiency of the management regime at the UWL. Environmental data were collected in this study, including the size of the Enclosure 13, temperature, lighting, seawater quality, and feeding data. The results showed that the showcase areas fulfilled the minimum requirements of the penguin, and no significant difference was found between morning and the evening temperatures. However, it differed significantly from the six lighting spots, and the pool's water was within the comfort zones. The diet provided for the African penguins at UWL follows their requirements. However, the amount of food supplied to each penguin at UWL is low compared to the food intake of the same individual penguin in the wild. Overall, the management of UWL is excellent practice. However, some weaknesses need further improvement.

MORTALITY TRENDS FOR BUDGERIGARS (MELOPSITTACUS UNDULATUS) HOUSED IN A WALK-THROUGH AVIARY IN A ZOO IN NORTH AMERICA, 2009–2019

Many zoos in North America feature walk-through exhibits that allow members of the public to interact with psittacine species, as these exhibits are popular with guests and can generate additional revenue. There is limited research available on the life expectancy and common causes of mortality of psittacines when group-housed in aviaries. This study compiled data on 496 budgerigar (Melopsittacus undulatus) mortalities at a walk-through aviary at a North American zoo from March 2009 to March 2019, including histopathology on 62 tissue sets collected post mortem, and gross necropsy data for 163 birds deceased from March 2015 to March 2019. The mean age at death or euthanasia of all fledged birds from 2015 to 2019 was 3.57 ± 1.58 yr. The most common causes of death or euthanasia found on gross necropsy were granulomatous disease (39.2%), trauma (16.0%), and Macrorhabdus ornithogaster (13.5%). The most common histologic finding was M. ornithogaster, described as the primary pathologic finding in 31.7% of submitted tissue sets, and recorded as a secondary pathologic finding in 53.2% of submitted tissue sets. Mycobacterial disease was the primary pathologic finding in 25.3% of submitted tissue sets, and was recorded as an additional pathologic finding in 35.4% of submitted tissue sets.

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

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