Chester Zoo

To manage ex situ breeding populations effectively, it is important to understand the factors that may lead to reproductive failure. In this study, we aim to understand factors associated with reproductive success in zoo-housed bush dogs (Speothos venaticus), and form evidence-based recommendations for their breeding management. We distributed a survey to global institutions housing bush dogs to collect data on factors which may affect litter survival. Responses were obtained from 30 zoos across 13 countries, providing data on 125 litter births between 2012 and 2022. Information from the Zoological Information Management System (ZIMS) and studbook records supplemented this dataset. We found that within northern temperate regions, the number of pups reared to the age of 1 month in bush dog litters (n = 112 litters) is linked to the ages of breeding individuals, prior breeding experience of females and birth season. The number of pups reared per litter declines with advancing maternal age, but this decline can be reduced by pairing with an older male; experienced females rear more pups per litter than inexperienced females, and litters born in the summer have better survival outcomes than other seasons. Sharing data between zoos provides greater statistical power to identify challenges associated with breeding lesser-researched species, allowing zoos to overcome these challenges through evidence-based management changes.

Assessing the welfare of zoo-housed great apes is essential to ensure high standards of care, maintain zoos' ethical and educational credibility, and support their conservation roles. However, welfare assessment remains challenging due to the complex cognitive, social, and behavioural needs of great apes and the limitations of existing evaluation methods. Many zoos rely on resource-based measures, which are easy to collect but lack the specificity needed to assess welfare accurately. In this study, we developed and tested a new standardized, evidence-based approach that integrated resource-based data with ecological and behavioural insights. This Ape Welfare Assessment, Resources and Ecology (AWARE) Tool was developed through collaboration with the Great Ape Welfare group (GAWg) and aimed to: (1) collect a holistic suite of resource and husbandry data that measures the constraints on the apes opportunities to express key naturalistic behaviours, (2) contextualize results within species-specific research on wild and captive great ape behavioural ecology and welfare, and (3) extend beyond existing zoo accreditation standards to support zoos aspirations for higher levels of welfare. Using data from zoo-housed chimpanzees, we tested whether this approach enhanced the validity of resource-based welfare assessments. Results demonstrate that the approach strengthens welfare evaluations and provides a more nuanced understanding of captive great ape wellbeing. We also propose a new validation framework for holistic welfare assessment tools such as this, where validating all individual indicators is neither feasible nor informative. Ultimately, we aim for the AWARE Tool to serve as a web-based resource for independent zoo use and formal welfare assessments. Future research will expand its application to gorillas and orangutans. This study represents a major leap towards establishing robust, species-informed and validated welfare assessment methodologies for zoo-housed great apes.

Abstract Private residential gardens provide habitats for many species of conservation concern, and often particular garden features are promoted to benefit biodiversity or particular faunal groups and species. However, quantifying and evidencing the benefits of garden features to particular species is challenging because the density and distribution of any feature varies between and within gardens and across wider urban landscapes. Here we present findings from a citizen science project that gathered information from 415 gardens across the City of Chester in the UK, to identify which garden features were related to garden use by Western European hedgehogs ( Erinaceus europaeus ) which is a species of conservation concern across Europe. Anthropogenic supplementary food was the only significant predictor of hedgehog occupancy, with 77.5% (95% CI: 68.8%, 84.3%) of gardens where food was supplied being used, compared to 49.9% (95% CI: 43.8%, 56.0%) in gardens without. Our findings show that no garden features were influential in predicting hedgehog occupancy. This included those features considered “wildlife-friendly” and promoted by conservation charities as being beneficial, such as log piles and bug hotels, illustrating the over-riding effects of supplementary food provisioning influencing garden use by hedgehogs.

ABSTRACTSinging is an ecologically important behaviour for songbirds. Syllables function as the building blocks of birdsong, so changes to their production will have implications for overall song structure. It is well established that anthropogenic disturbance can influence syllable production in wild songbird populations, but the effect of anthropogenic disturbance on syllable production in ex situ populations has not been studied. We set out to fill this gap by comparing the syllable production of Chester Zoo's Bali myna (Leucopsar rothschildi) population during a period of zoo closure in 2020 (due to the COVID‐19 lockdown) to a period of normal zoo opening in 2019. The number of syllables per song, the rate at which syllables were produced and the diversity of syllables all showed evidence of plasticity across days and years. However, only the number of syllables per song responded significantly to anthropogenic disturbance. Changes in syllable number due to anthropogenic disturbance could mitigate potential signal masking from unpredictable noise, although communication efficacy may still be affected. As a result, changes in vocal communication could impact conservation breeding programmes by altering the way that individuals interact with conspecifics.

ABSTRACT Acoustic indices are promising tools for ecoacoustic studies and may be useful in zoos for passive acoustic monitoring of enclosures and their inhabitants. To validate their suitability for these applications, it is important to understand how different sounds in the environment affect them. Zoos have unique soundscapes with anthropogenic sounds such as human voices and mechanical noises often prevalent alongside high levels of animal-produced sounds; however, the influence of these sounds on acoustic indices in zoos has yet to be studied. This study investigates how different sound types recorded in aviaries at Chester Zoo in 2019 and 2020 affected three widely used acoustic indices: the Sonic Heterogeneity Index (SHI), the Acoustic Entropy Index (H), and the Normalised Difference Soundscape Index (NDSI). All three indices increased with avian vocalisations; H and SHI increased with human voices; only H increased with non-vocal anthropophonic sounds; SHI and NDSI increased with non-vocal biophonic sounds; and SHI increased but H decreased with the sound of wind. Because each index captures sound types in different ways, using all three in conjunction may provide researchers and practitioners with a more detailed understanding of the acoustic environments in zoos and other anthropogenically dominated environments.

Neoplastic diseases are poorly documented in Suidae species. This report describes a 15-year-old female common warthog (Phacochoerus africanus) with multicentric lymphoma, phaeochromocytoma and C-cell carcinoma. The animal had multiple episodes of weakness and epistaxis in the months before death, until it was euthanized for acute lethargy and recumbency. Post-mortem examination revealed haemoabdomen originating from enlarged lymph nodes at the mesenteric root. The warthog had generalized lymphadenopathy, consistent with B-cell lymphoma based on CD20 immunohistochemistry. The adrenal glands were bilaterally enlarged, one by an ovoid mass arising from the medulla that effaced the cortex, consistent with a well-differentiated phaeochromocytoma, based on histomorphology and chromogranin A immunopositivity. This animal also had a unilateral, encapsulated thyroid nodule characterized by abundant interstitial calcitonin-positive amyloid and irregular tubular structures, similar to human medullary thyroid carcinoma. There was moderate metastatic calcification of the lungs and upper respiratory mucosa, presumably part of a paraneoplastic syndrome. The combination of phaeochromocytoma and an amyloid-rich thyroid carcinoma in this animal is suggestive of multiple endocrine neoplasia type 2 syndrome which, although well described in humans, is rarely reported in animals. Further investigations of genetic aspects are recommended.

Unsustainable wild meat hunting poses a significant threat to wildlife and tropical forest ecosystems. While high levels of extraction linked to commercial trade have received significant attention, the sustainability of subsistence hunting by Indigenous Peoples in Africa has been less studied. Understanding how changing lifestyles, particularly the sedentarisation of former hunter-gatherers, have affected the use of forest resources is crucial for wildlife conservation and livelihoods. The spatial management of hunting through the establishment of no-take zones, which act as sources for adjacent hunting areas, offers promise for the sustainability of Indigenous livelihoods. We conducted an extensive camera trap study in hunting areas subject to source-sink dynamics used by 10 sedentarised Baka communities. We compared species richness, occupancy, abundance, and community composition to a relatively non-hunted reference area in the adjacent Dja Faunal Reserve. Subsistence hunting by the Baka had a limited impact on species richness but significantly altered community composition and the abundance of carnivores, seed dispersers and granivores. These changes highlight that even the spatial management of hunting may have consequences for the sustainability of hunting systems and the functional ecology of tropical forests.

Abstract A geriatric, 16‐year‐9‐month‐old, male snow leopard ( Panthera uncia ) under human care was necropsied after euthanasia over concerns for worsening chronic kidney disease and bilateral blindness. Gross and histological examinations revealed necrotising frontal sinusitis and osteomyelitis with mixed‐cellular rhinotracheitis, affecting the right frontal sinus, right nasal cavity and trachea, respectively, with intralesional and cilia‐associated Gram‐negative bacilli detected. Microbiological cultures were inconclusive, although Bordetella bronchiseptica and feline herpesvirus 1 were positive on PCR analysis. Immunohistochemistry, however, refuted active feline herpesvirus 1 involvement. Marked, chronic, bilateral, renal degeneration and fibrosis (chronic kidney disease), mild hepatic cirrhosis, bilateral chronic degenerative stifle joint disease and testicular intratubular seminoma were also detected on postmortem examination. No gross ocular or optic nerve lesions were identified; however, histology indicated bilateral diffuse outer retinal atrophy and retinal detachment, supportive of clinical blindness at time of death. This case represents the first report of chronic rhinosinusitis and osteomyelitis in a snow leopard.

Maintaining a diverse gene pool is important in the captive management of zoo populations, especially in endangered species such as the pink pigeon (Nesoenas mayeri). However, due to the limited number of breeding individuals and relaxed natural selection, the loss of variation and accumulation of harmful variants is inevitable. Inbreeding results in a loss of fitness (i.e., inbreeding depression), principally because related parents are more likely to transmit a copy of the same recessive deleterious genetic variant to their offspring. Genomics-informed captive breeding can manage harmful variants by artificial selection, reducing the genetic load by avoiding the inheritance of two copies of the same harmful variant. To explain this concept in an interactive way to zoo visitors, we developed a sonification game to represent the fitness impacts of harmful variants by detuning notes in a familiar musical melody (i.e., Beethoven's Für Elise). Conceptually, zoo visitors play a game aiming to create the most optimal pink pigeon offspring in terms of inbreeding depression. They select virtual crosses between pink pigeon individuals and listen for the detuning of the melody, which represents the realised load of the resultant offspring. Here we present the sonification algorithm and the results of an online survey to see whether participants could identify the most and least optimal offspring from three potential pink pigeon offspring. Of our 98 respondents, 85 (86.7%) correctly identified the least optimal offspring, 73 (74.5%) correctly identified the most optimal, and 62 (63.3%) identified both the most and least optimal offspring using only the sonification.

Songs play an important role in mate choice for many bird species. Females of some species prefer mates with song characteristics such as familiarity, complexity, or specific temporal or note features. Different song characteristics may provide distinct information about the birds that produced those songs. For example, familiarity may be a signal of local adaptation, locally relevant information or learned behaviours, or genetic compatibility, while song complexity may be a signal of overall genetic quality. However, how song characteristics combine to affect female preferences remains poorly understood. We examined female preference for song familiarity and complexity using the Java sparrow (Padda oryzivora) as a model species. Females were presented with pairs of song stimuli; familiar and unfamiliar songs in familiarity trials, and songs differing in note repertoire or linearity in complexity trials. Females preferred their fathers' songs over unfamiliar songs, but we did not find strong evidence that females generalized this preference to other socially related individuals. Females also preferred complex songs, specifically those with larger note repertoires and with lower linearity, even when controlling for familiarity. Our results suggest that female song preference in Java sparrows is multi-faceted, with different song characteristics potentially offering different information to choosy females.