The historical development of zoo elephant survivorship

Liver and Let Die? A Retrospective Analysis of Secretarybird Mortality in European Zoos

The secretarybird (Sagittarius serpentarius) is a threatened African raptor species, and as such requires conservation attention. While the species is managed under a European Association of Zoos and Aquaria (EAZA) Ex-situ Programme (EEP), no studies of mortality are currently available. A retrospective mortality project was therefore conducted to identify the most common causes of death in captive secretarybirds, with a view to informing management decisions. Data were collected by requesting the postmortem reports from zoos where secretarybirds had died and combining this with the existing data recorded in the Zoological Information Management System. Overall, 167 birds were recorded as having died within the EEP population, of which post-mortem information was available for 51 (30.54%) individuals. Trauma was the most common cause of death identified (22 birds, 13.17%), with infection appearing as the second most prevalent cause (15 birds, 8.98%). One incidental finding at postmortem was that many (9) birds showed evidence of liver damage, with reports of bacterial hepatitis, staphylococcal infection, lesions, and dark coloration. Further research into liver complications and diet composition for secretarybirds may therefore have value in reducing mortality. Similarly, investigating strategies to reduce trauma caused by other enclosure occupants or conspecifics may have value in lengthening lifespans for this endangered species.

Comparison of animal welfare assessment tools and methodologies: need for an effective approach for captive elephants in Asia

Welfare is a fundamental aspect of animal management and conservation. In light of growing public awareness and welfare concerns about captive elephants, there is an urgent need for comprehensive, globally coordinated efforts for Asian elephants (Elephas maximus) that participate in religious, logging, or tourist activities in range countries where the majority reside, and where welfare issues have been identified but not addressed. This review provides a comparative analysis of available animal assessment tools. Each offers distinct features for assessment that allow institutions to select criteria for specific needs and available resources. Most are applied to general animal welfare assessments, although some are tailored to particular species, including elephants. The tools span diverse formats, from digital to primarily paper-based assessments. Assessments operate at individual and institutional levels and across multiple welfare domains. Methodologies rely on keeper ratings or expert evaluations, incorporate numerical scoring and Likert scales for welfare grading, and encompass inputs including behaviors, health, and physiological indicators. For tourist camp elephants, one challenge is that the tools were developed in zoos, which may or may not have application to non-zoological settings. Digital tools and assessment methodologies such as keeper ratings face logistical challenges when applied across tourist venues. As with any tool, reliability, validity, and repeatability are essential and must address the unique welfare challenges of diverse captive settings. We propose that a holistic, context-specific, evidence-based, and practical tool be developed to ensure high elephant welfare standards in non-zoological facilities throughout Asia.

Putting zoo animal cancer into perspective

As part of a comparative research agenda that promises insights that help extend the human lifespan and combat cancer, cancer prevalence in zoo animals has received recent attention. Here, we want to draw attention to a principle of cancer research that was introduced into the zoo world as early on as 1933, but that seems to have gone somewhat forgotten: Cancer is mainly a disease of old age, and therefore studies aiming at identifying taxa that are particularly susceptible or resistant to cancer must control for whether the respective zoo populations are 'old.' In a comparative context, 'old age' cannot be measured in absolute terms (e.g., years), but only in relation to a species' maximum lifespan: Species that achieve, across zoos, a higher mean lifespan as a percent of their maximum lifespan are 'older.' When applying this metric to former as well as more recently published data on cancer prevalence, it appears that those species that become relatively old in zoos-in particular, the carnivores-have a relatively high cancer prevalence. Any improvement in animal husbandry-which reduces premature deaths-should, by default, lead to more cancer. Cancer in zoo animals, like any other old-age condition, might therefore be embraced as a proxy for good husbandry. Rather than following a sensationalist approach that dramatizes disease and death per se, zoos should be clear about what their husbandry goals are, what relative longevities they want to achieve for which species, and what old-age diseases they should therefore expect: in the end, one has to die of something.

What is the role of the studbook in zoo and aquarium research?

In zoos and aquariums globally, studbooks provide a format by which threatened or important species populations can be carefully managed. These documents can be used to answer complex questions about animal population demographics, animal husbandry, breeding success and mortality. Given the time-intensive nature of studbook collation, only a subset of all animal species held in zoological facilities are managed using these programs. The purpose of this project was to identify how studbooks are being used by researchers, the topics being investigated, and the taxa being covered. To achieve this, data were collected on the types of research paper being produced using studbook information. A literature search, covering several zoo and aquarium journals, was utilized. Data on the types of studbook available were additionally collected for three international zoo organizations. A Poisson regression was run to determine the predictive power of taxonomic class, animal threat status and studbook type on a studbook featuring in published research. Overall, the study identified that taxonomic class and threat status were significant predictors of the number of published studbook papers, with threatened species being more likely to appear in papers. Additionally, population demography was the most common use of studbook data, followed by genetics and reproduction. Not all taxonomic groups were featured in the literature, with mammals featuring much more frequently than would be expected based on the types of studbook available.

Historical development of the survivorship of zoo rhinoceroses-A comparative historical analysis

Zoo animal husbandry is a skill that should be developing constantly. In theory, this should lead to an improvement of zoo animal survivorship over time. Additionally, it has been suggested that species that are at a comparatively higher risk of extinction in their natural habitats (in situ) might also be more difficult to keep under zoo conditions (ex situ). Here, we assessed these questions for three zoo-managed rhinoceros species with different extinction risk status allocated by the IUCN: the "critically endangered" black rhino (Diceros bicornis), the "vulnerable" greater one-horned (GOH) rhino (Rhinoceros unicornis), and the "near threatened" white rhino (Ceratotherium simum). Comparing zoo animals ≥1 year of age, the black rhino had the lowest and the white rhino the highest survivorship, in congruence with their extinction risk status. Historically, the survivorship of both black and white rhino in zoos improved significantly over time, whereas that of GOH rhino stagnated. Juvenile mortality was generally low and decreased even further in black and white rhinos over time. Together with the development of population pyramids, this shows increasing competence of the global zoo community to sustain all three species. Compared to the continuously expanding zoo population of GOH and white rhinos, the zoo-managed black rhino population has stagnated in numbers in recent years. Zoos do not only contribute to conservation by propagating ex situ populations, but also by increasing species-specific husbandry skills. We recommend detailed research to understand specific factors responsible for the stagnation but also the general improvement of survivorship of zoo-managed rhinos.

Losing the forest for the tree? On the wisdom of subpopulation management

Animal habitats are changing around the world in many ways, presenting challenges to the survival of species. Zoo animal populations are also challenged by small population sizes and limited genetic diversity. Some ex situ populations are managed as subpopulations based on presumed subspecies or geographic locality and related concerns over genetic purity or taxonomic integrity. However, these decisions can accelerate the loss of genetic diversity and increase the likelihood of population extinction. Here I challenge the wisdom of subpopulation management, pointing out significant concerns in the literature with delineation of species, subspecies, and evolutionarily significant units. I also review literature demonstrating the value of gene flow for preserving adaptive potential, the often-misunderstood role of hybridization in evolution, and the likely overstated concerns about outbreeding depression, and preservation of local adaptations. I argue that the most effective way to manage animal populations for the long term be they in human care, in the wild, or if a captive population is being managed for reintroduction, is to manage for maximum genetic diversity rather than managing subpopulations focusing on taxonomic integrity, genetic purity, or geographic locale because selection in the future, rather than the past, will determine what genotypes and phenotypes are the most fit. Several case studies are presented to challenge the wisdom of subpopulation management and stimulate thinking about the preservation of genomes rather than species, subspecies, or lineages because those units evolved in habitats that are likely very different from those habitats today and in the future.

Hormonal variation and temporal dynamics of musth in Asian elephants (Elephas maximus) are associated with age, body condition and the social environment

The sustainability of endangered Asian elephants in human care is threatened in part by low breeding success and concerns over individual animal wellbeing. Male elephants have received less research attention compared to females, yet males deserve special consideration due to their unique reproductive biology (particularly the sexual state of "musth") and the complex interaction of physiological, environmental, and social pressures they face. We measured fecal androgen metabolites (FAMs), fecal glucocorticoid metabolites (FGMs), and fecal triiodothyronine metabolites (FT3s) collected weekly over approximately 12 months from 26 male Asian elephants housed in zoos across the US, hypothesizing that FAM, FGM, and FT3 concentrations would be associated with temporal correlates of musth and would vary further with intrinsic (musth status, age, body condition) and extrinsic (social environment) factors. The duration of each musth episode was positively associated with exposure to male conspecifics and negatively associated with body condition. Further, elevated FAM concentrations were associated with social exposure, age, and body condition, and FGM concentrations also varied with age and body condition. FT3 concentrations were not associated with any factor we measured. We also identified periods of lower FAM concentration than confirmed musth episodes (but still higher than baseline FAM concentrations) that we termed "elevated FAM episodes." The durations of these episodes were negatively correlated with exposure to other male elephants. Together, these results provide evidence that hormone profiles (including those that are predicted to change around musth) vary significantly between male Asian elephants in a way that may be attributed to intrinsic and extrinsic factors. Studies like these serve to enhance the sustainability of ex-situ populations by providing wildlife managers with information to enhance the health, welfare, and reproduction of threatened species like Asian elephants.