Pteropus Livingstonii Research Articles

Thirty years of conservation breeding: Assessing the genetic diversity of captive Livingstone's fruit bats.

Fruit bats (genus Pteropus) are typically island-endemic species important in seed dispersal and reforestation that are vulnerable to increased extinction risk. An effective method of reducing extinction risk in vulnerable species that cannot be conserved in their native habitat is establishing an ex-situ captive breeding programme. Due to anthropogenic threats and low population numbers, in the early 1990s, a captive breeding programme was established at Jersey Zoo, British Isles, for Critically Endangered Livingstone's fruit bats (Pteropus livingstonii). Here we use six polymorphic microsatellite loci to assess genetic diversity in the captive breeding population of Livingstone's fruit bats (P. livingstonii), 30 years after the programme's establishment, investigating change over generations and comparing our findings with published data from the wild population. We found no significant difference between the genetic diversity in the captive and wild populations of Livingstone's fruit bats (P. livingstonii), in both expected heterozygosity and allelic richness. The captive population has retained a comparable level of genetic diversity to that documented in the wild, and there has been no significant decline in genetic diversity over the last 30 years. We advise that a full pedigree of the paternal lineage is created to improve the management of the captive breeding programme and further reduce the possibility of inbreeding. However, it appears that the captive breeding programme is currently effective at maintaining genetic diversity at levels comparable to those seen in the wild population, which suggests reintroductions could be viable if genetic diversity remains stable in captivity.

In Absentia—Can a Lack of Behaviour Be a Useful Welfare Indicator? An Application to the Captive Management of Livingstone’s Fruit Bats, Pteropus livingstonii

Non-invasive behavioural indicators of welfare can be particularly useful for managing captive breeding populations of endangered species; these allow individual welfare to be monitored and reproductive success maximised without the need for capture and restraint methods. However, most studies focus on the behaviours whose presence or frequency can predict welfare issues; the absence of a behaviour is less frequently considered an indicator of welfare. Here, we investigate potential behavioural correlates with welfare-related health states in captive Livingstone’s fruit bats (Pteropus livingstonii), a critically endangered species that can become obese due to restricted space and reduced activity rates compared with wild populations. In this study, behavioural data were collected on males (which are particularly prone to obesity). Hurdle models were used to separately determine the factors predicting the presence or absence of behaviour and the frequency of observed behaviours. Whilst significantly lower levels of vigilance were observed in males with a larger body mass, those with diagnosed health issues were significantly more likely to show an absence of locomotion and foraging behaviour. Males with a lower body mass were also more likely to show an absence of foraging behaviour. Our study demonstrates how the absence of a behaviour can be informative as to an individual’s welfare state. This study has identified behavioural profiles that can be used to flag at-risk individuals, reducing the need for potentially stressful handling and improving our ability to safeguard the welfare of individuals within a large captive group.

Seasonal trends and population status of the highly threatened Pteropus livingstonii in the Comoros archipelago

Flying foxes of the genus Pteropus, especially those inhabiting islands, face increasing pressure from anthropogenic threats. A first step to implementing effective conservation actions is to establish monitoring projects to understand a species’ population status and trend. Pteropus species are highly affected by seasonality which further requires regular, repeated, and long-term data to understand population trends, and reactions to severe weather events. In the present case study, a regular, bi-annual population census was implemented on Comoros between 2016 and 2023 for the highly threatened Livingstone’s fruit bat, Pteropus livingstonii, and compared the results of standardized monitoring to historical population data. Seasonality had a large impact on the number of bats found at roost sites, with more bats present in the wet season, but the data over the past eight years revealed no significant in- or decrease in the number of bats counted on the island Anjouan. We estimated around 1,200–1,500 bats on Anjouan and 300–400 bats on Mohéli, and found that landcover type has no measurable effect on population distribution at roost sites. Our study highlights the need for long-term surveys to understand past population trends and that single counts are not sufficient to draw final conclusions of a species’ status.

Weight as an indicator of enclosure suitability in Livingstone's fruit bats (Pteropus livingstonii).

Obesity is common in zoo animals, and both dietary management and the provision of adequate opportunities for exercise are needed to tackle it. We used 30 years of records from Jersey Zoo to compare the weight and forearm length of wild and captive-born Livingstone's fruit bats (Pteropus livingstonii), and to assess the impact on weight of enclosure space. The mean capture weight of wild-caught male Livingstone's bats was 657 g, significantly higher than that of females (544 g). In both wild and captive-born bats, males had significantly longer forearms than females, but there was no effect of birth location. Males weighed more in the mating season than at other times of year. Both sexes gained more weight during development if born in enclosures that restricted flight rather than a large aviary; this was particularly noticeable in females. After reaching maturity at 3 years, weights of bats born in restricted enclosures continued to increase, reached a peak of over 1000 g at 8-10 years, and then declined in both sexes. The weight of bats born in the aviary remained more stable after the age of three. Like wild bats, adult females born in the aviary weighed less than males. However, females born in restricted enclosures weighed more than males born in the same enclosures. Enclosure designs that maximize opportunities for flight can limit excessive weight gain in captive fruit bats and may therefore improve fitness and health, essential in planning for future reintroduction programs.

Habitat fragmentation increases genetic distance between fruit bat subpopulations

AbstractLivingstone's fruit bat (Pteropus livingstonii) is among the most threatened bats worldwide. As the species is an important pollinator and seed disperser of Comoros plants with a crucial role in forest regeneration, it is critical to understand how human‐induced habitat disturbance impacts genetic structure at fine spatial scales in order to define conservation strategies. In this study, we assessed the level of genetic structure between eight colonies of the species and found that this was strong genetic structures between roosts that can be explained by isolation due both to distance and habitat fragmentation. Mitigation measures should aim to restore population connectivity.

Predictors of dominance rank and agonistic interactions in captive Livingstone's fruit bats.

Male dominance hierarchies have been studied in many animals but rarely in bats (Chiroptera). The dominance rank of social animals may dictate access to resources and mates; therefore, it has important implications for an individual's fitness and is crucial for successful captive management. Between January and December 2018, at both Bristol Zoo Gardens (Bristol, UK) and Jersey Zoo (Jersey, British Isles), we observed 19 male Livingstone's fruit bats Pteropus livingstonii using focal follows for 345 h overall, noting the outcome of all agonistic interactions. We recorded instigators of interactions, along with winners and losers, and analyzed these data using the R-package "EloRating" to create Elo-rating temporal plots of dominance ranks. We used generalized linear mixed models and multiple linear regression to analyze interaction data and test hypotheses regarding predictors of dominance rank, frequency of agonistic interaction, and choice of interaction partner. Age was positively correlated with dominance rank up to around year 9, when an asymptote was attained. Highly ranked bats instigated the most agonistic interactions, and largely directed these interactions at bats with much lower rankings than themselves. Hierarchies were extremely stable throughout the data collection period at both sites. We conclude that Livingstone's fruit bats have a stable linear dominance hierarchy, with high-ranking, typically older males instigating the most interactions with lowest ranking males to secure dominance rank. This study adds to the limited discourse on Pteropus social behaviors, indicating that some bat species may have social systems similar in complexity to some nonhuman primates.

Staphylococcus aureus lineages associated with a free-ranging population of the fruit bat Pteropus livingstonii retained over 25 years in captivity

Conservation of endangered species has become increasingly complex, and costly interventions to protect wildlife require a robust scientific evidence base. This includes consideration of the role of the microbiome in preserving animal health. Captivity introduces stressors not encountered in the wild including environmental factors and exposure to exotic species, humans and antimicrobial drugs. These stressors may perturb the microbiomes of wild animals, with negative consequences for their health and welfare and hence the success of the conservation project, and ultimately the risk of release of non-native organisms into native ecosystems. We compared the genomes of Staphylococcus aureus colonising critically endangered Livingstone’s fruit bats (Pteropus livingstonii) which have been in a captive breeding programme for 25 years, with those from bats in the endemic founder population free ranging in the Comoros Republic. Using whole genome sequencing, we compared 47 isolates from captive bats with 37 isolates from those free ranging in the Comoros Republic. Our findings demonstrate unexpected resilience in the bacteria carried, with the captive bats largely retaining the same two distinctive lineages carried at the time of capture. In addition, we found evidence of genomic changes which suggest specific adaptations to the bat host.

Social roles influence cortisol levels in captive Livingstone's fruit bats (Pteropus livingstonii)

A critical component of conserving and housing species ex situ is an explicit scientific understanding of the physiological underpinnings of their welfare. Cortisol has been repeatedly linked to stress, and therefore used as an indicator of welfare for many species. In order to measure cortisol in the Livingstone's fruit bat (Pteropus livingstonii; a critically endangered keystone species) without disturbing the captive population, we have developed and validated a non-invasive, novel hormone extraction procedure and faecal glucocorticoid assay. A total of 92 faecal samples, 73 from the P. livingstonii breeding colony at Jersey Zoo, Channel Islands and 19 samples from P. livingstonii housed at Bristol Zoological Gardens, UK, have been collected and analyzed. Mixed-effect modelling of the influence of physiological state variables on cortisol concentration revealed that lactating females had higher cortisol levels than non-lactating females, indicating that our assay is measuring biologically relevant hormone concentrations. Males and older bats also had higher cortisol than non-lactating females and younger individuals. Further analysis applied social network methodology to compare the cortisol levels of bats with different social roles. We found that individuals that linked social groups possessed higher than average cortisol levels and conversely, individuals with high-quality, positive relationships had lower cortisol levels. These results demonstrate, for the first time in a bat species, social mediation of stress hormones. Lastly, the frequency of vocalisation was found to positively correlate with cortisol concentration in males, suggesting that this behaviour may be used by animal management as a visual indicator of a bat's hormonal status. Hence, this research has provided unique insights and empirical scientific knowledge regarding the relationship between the physiology and social behaviour of P. livingstonii, therefore allowing for recommendations to be made to optimise bat welfare at the individual level.

Principal Component Analysis as a novel method for the assessment of the enclosure use patterns of captive Livingstone’s fruit bats (Pteropus livingstonii)

The Spread of Participation Index (SPI) is a standard tool for assessing the suitability of enclosure design by measuring how captive animals access space. This metric, however, lacks the precision to quantify individual-level space utilization or to determine how the distribution of resources and physical features within an enclosure might influence space use. Here we demonstrate how Principal Component Analysis (PCA) can be employed to address these aims and to therefore facilitate both individual-level welfare assessment and the fine-scale evaluation of enclosure design across a range of captive settings. We illustrate the application of this methodology by investigating enclosure use patterns of the Livingstone’s fruit bat (Pteropus livingstonii) population housed at Jersey Zoo. Focal sampling was used to estimate the time each of 44 individuals in the first data collection period and 50 individuals in the second period spent in each of 42 theoretical enclosure sections. PCA was then applied to reduce the 42 sections to five and seven ecologically relevant “enclosure dimensions” for the first and second data collection periods respectively. Individuals were then assigned to the dimension that most accurately represented their enclosure use patterns based on their highest dimensional eigenvalue. This assigned dimension is hereafter referred to as the individual’s Enclosure Use Style (EUS). Sex was found to be significantly correlated with an individual’s EUS in the second period, whilst age was found to significantly influence individual fidelity to assigned EUS. When assessing the effect of resource location on group-level preference for certain sections, the presence of feeders and proximity to public viewing areas in period one, and feeders and heaters in period two, were positively correlated with space use. Finally, individual EUS remained consistent between both data collection periods. We interpret these results for this species in the context of its observed behavioural ecology in the wild and evaluate the degree to which the current captive enclosure for this population allows for optimal individual welfare through the facilitation of spatial choice. We then explore how these methods could be applied to safeguard captive animal welfare across a range of other scenarios.

Noninvasive genetic sampling for flying foxes: a valuable method for monitoring demographic parameters

AbstractEstablishing effective wildlife conservation measures requires accurate demographic information such as population size and survival probability: parameters that can be extremely difficult to obtain. This is especially the case for threatened species, which are often rare and sometimes occupy inaccessible areas. While noninvasive genetic sampling (NIGS) techniques are promising tools for providing demographic data, these methods may be unreliable in certain situations. For instance, fecal samples of frugivorous species in tropical areas degrade rapidly, affecting the usability of the genetic material. In this study, we compared (1) NIGS capture–mark–recapture (NIGS‐CMR) with conventional CMR to determine their potential in estimating demographic parameters of fruit bats, and (2) the precision of these demographic parameters and the associated costs given varying sampling designs through simulations. Using Livingstone’s fruit bats (Pteropus livingstonii) fecal samples, microsatellite markers were tested and genotyping success and error rates were assessed. The average genotyping success rate was 77%, and the total genotyping error rate for all loci was low (allelic dropout rate = 0.089, false alleles rate = 0.018). Our results suggested that five loci were required to identify individuals. Simulations showed that monitoring the species over a 9‐yr period with a recapture rate of 0.20 or over a 6‐yr period with a recapture rate of 0.30 seems appropriate to obtain valuable demographic parameters. Overall, in comparison to conventional CMR, NIGS‐CMR offers a better method for estimating demographic parameters and subsequently for conducting long‐term population monitoring in flying foxes due to the fact that (1) sample collection is easy and the level of genotyping errors in the laboratory is low and (2) it is cheaper, less time‐consuming, and less disturbing to individual animals. We strongly advocate an approach that couples a pilot study with simulations as done in this study in order to choose the most efficient monitoring method for a given species or context.

Using GPS tracking for fruit bat conservation

AbstractUnderstanding the ecology of species is key to the development of effective conservation measures. For many fruit bat species, however, even baseline knowledge of ecology and behaviour is lacking. To identify feeding sites of the Critically Endangered Livingstone's flying fox Pteropus livingstonii on the island of Anjouan, Comoros, we piloted the use of GPS loggers. Two bats (one female, one male) were tagged in early 2019, and data collected for 217 and 35 days, respectively. Acceleration data facilitated the classification of location points into behavioural categories. Potential feeding sites were located by cluster analysis of all location points that were attributed to a behavioural category in which feeding could occur. One important feeding site was located in an agricultural area. This is the first time quantitative behavioural data have been collected for Livingstone's flying foxes, providing insight into the ecological needs of this threatened species. These findings have the potential to inform applied conservation management decisions for protecting the resources required for the survival of this species.

Closed genome sequences of Staphylococcus lloydii sp. nov. and Staphylococcus durrellii sp. nov. isolated from captive fruit bats (Pteropus livingstonii).

The increasing availability of whole genome sequencing of bacteria has accelerated the discovery of novel species which may not have been easy to discriminate using standard phenotypic or single gene methods. Phylogenomic analysis of genome sequences from a collection of coagulase-negative staphylococcal species isolated from captive fruit bats revealed two clusters which were close to Staphylococcus kloosii. To assess the relatedness of the strains we used digital DNA–DNA hybridization (dDDH) and two methods for average nucleotide identity (ANI) computation which predicted two novel species having dDDH less than 70 % and ANI less than 95%. We propose these species as Staphylococcus lloydii sp. nov. (type strain 23_2_7_LYT=NCTC 14453T=DSM 111639T) and Staphylococcus durrellii sp. nov (type strain 27_4_6_LYT=NCTC 14454T=DSM 111640T).

Social Experience of Captive Livingstone's Fruit Bats (Pteropus livingstonii).

Simple SummaryThe maintenance and stability of social experience is an especially important element of the captive welfare of zoo-housed species. The population of critically endangered Livingstone’s fruit bats (Pteropus livingstonii) resident at Jersey Zoo display a complex social structure of affiliative and aggressive interactions. Subgroups defined by individual characteristics contribute in different ways to this structure. Social information, illuminated through the use of social network analysis techniques, could be used in the future to promote social stability and safeguard individual welfare when making evidence-based husbandry decisions.Social network analysis has been highlighted as a powerful tool to enhance the evidence-based management of captive-housed species through its ability to quantify the social experience of individuals. We apply this technique to explore the social structure and social roles of 50 Livingstone’s fruit bats (Pteropus livingstonii) housed at Jersey Zoo, Channel Islands, through the observation of associative, affiliative, and aggressive interactions over two data collection periods. We implement binomial mixture modelling and characteristic-based assortment quantification to describe the complexity and organisation of social networks, as well as a multiple regression quadratic assignment procedural (MRQAP) test to analyse the relationship between network types. We examine the effects of individual characteristics (i.e., sex, age, and dominance rank) on social role by fitting models to explain the magnitude of node metrics. Additionally, we utilize a quadratic assignment procedural (QAP) test to assess the temporal stability of social roles over two seasons. Our results indicate that P. livingstonii display a non-random network structure. Observed social networks are positively assorted by age, as well as dominance rank. The frequency of association between individuals correlates with a higher frequency of behavioural interactions, both affiliative and aggressive. Individual social roles remain consistent over ten months. We recommend that, to improve welfare and captive breeding success, relationships between individuals of similar ages and dominance levels should be allowed to persist in this group where possible, and separating individuals that interact frequently in an affiliative context should be avoided.

DIVERSITY OF STAPHYLOCOCCAL SPECIES CULTURED FROM CAPTIVE LIVINGSTONE'S FRUIT BATS (PTEROPUS LIVINGSTONII) AND THEIR ENVIRONMENT.

Livingstone's fruit bats (Pteropus livingstonii) are critically endangered and a captive population has been established as part of the International Union for Conservation of Nature Species Action Plan. The largest colony, in Jersey Zoo, was sampled for staphylococcal carriage and at infection sites, as disease associated with staphylococci had previously been found. Staphylococci were cultured from swabs from 44 bats (skin, oropharynx, mouth ejecta, skin lesions) and from their enclosure. The isolates were identified by matrix-assisted laser desorption-ionization time of flight mass spectrometry; antimicrobial susceptibility testing was performed by disc diffusion and screening for mecA and mecC. Seventeen species of coagulase-negative staphylococci including Staphylococcus xylosus, S. kloosii, S. nepalensis, and S. simiae were isolated. Staphylococcus aureus was identified from both carriage and lesional sites. These findings suggest S. nepalensis may be part of the normal carriage flora of bats. Antimicrobial resistance rates were low and methicillin-resistant Staphylococcus aureus (MRSA) was not identified. Sampling of mouth ejecta for staphylococci may provide results representative for carriage sites.

Flight patterns in zoo‐housed fruit bats (Pteropus spp.)

Maintaining the capacity for sustained flight in captivity is a key goal for the management of threatened fruit bats. We developed quantifiable descriptions of flight complexity and used them to assess the suitability of an enclosure for two species of fruit bat of differing size, the large Livingstone's fruit bat, Pteropus livingstonii, and the smaller Rodrigues fruit bat, Pteropus rodricensis, in a two-part study. In Phase 1, Rodrigues fruit bats flew more often than Livingstone's fruit bats and although the majority of flights in both species were linear, Rodrigues fruit bats were more likely to display complex flight paths involving turns, while flights by Livingstone's fruit bats were more likely to end in a crash-landing than Rodrigues fruit bat flights. The enclosure may therefore not have been large enough for Livingstone's fruit bats to display a full range of flight behavior over longer distances. In Phase 2, juvenile Livingstone's fruit bats ( < 3 years old) flew more than twice as often as younger adults (3-10 years old) did. Older adult Livingstone's fruit bats over the age of 10 years were not observed to fly. We could not separate out the effects of age, weight and environment during development as these factors were strongly correlated in our study; future work in this area will be very important in understanding the factors that affect flight in captive bats, and how it can be encouraged by appropriate enclosure design.

The contrasting genetic patterns of two sympatric flying fox species from the Comoros and the implications for conservation

Pteropus livingstonii and Pteropus seychellensis comorensis are endemic fruit bat species that are among the most threatened animals in the Comoros archipelago. Both species are pollinators and seed dispersers of native and cultivated plants and are thus of crucial importance for the regeneration of natural forests as well as for cultivated plantations. However, these species are subject to strong anthropogenic pressures and face one of the highest rates of natural habitat loss reported worldwide. Yet little is known about the population genetic structure of these two species, making it difficult to define relevant conservation strategies. In this study, we investigated for the two flying fox species (1) the level of genetic diversity within islands, as well as across the archipelago and (2) the genetic structure between the two islands (Anjouan and Moheli) for P. livingstonii and between the four islands of the archipelago (Anjouan, Moheli, Grande Comore and Mayotte) for P. s. comorensis using mitochondrial and microsatellite markers. The results revealed contrasting patterns of genetic structure, with P. s. comorensis showing low genetic structure between islands, whereas P. livingstonii exhibited high levels of inter-island genetic differentiation. Overall, the genetic analyses showed low genetic diversity for both species. These contrasting genetic patterns may be the result of different dispersal patterns and the populations’ evolutionary histories. Our findings lead us to suggest that in terms of conservation strategy, the two populations of P. livingstonii (on Anjouan and Moheli islands) should be considered as two separate management units. We recommend focusing conservation efforts on the Anjouan population, which is the largest, exhibits the highest genetic diversity, and suffers the greatest anthropogenic pressure. As for P. s. comorensis, its four populations could be considered as a single unit for conservation management purposes. For this species, we recommend protecting roosting trees to reduce population disturbance.

A habitat suitability analysis at multi-spatial scale of two sympatric flying fox species reveals the urgent need for conservation action

In this study we used a multi-spatial scale approach to investigate habitat suitability, roosting characteristics, and ecological niche in two flying fox species on the Comoros Islands—Pteropus livingstonii and Pteropus seychellensis comorensis. At a broad scale, we assessed the ecological niche and habitat suitability for both species using the Species Distribution Modeling method based on the recent ensembles of small models (ESM) approach. At a fine scale, Ecological Niche Factor Analysis (ENFA) was applied to assess habitat selection by each species. Direct observation was used at each roost to estimate the total number of individuals and to identify the roost characteristics. At both broad and fine scales, the analyses highlighted clear niche partitioning by the two species. We found that P. livingstonii has a very limited distribution, restricted to steep, high-elevation slopes of the islands’ remaining natural forests, and the patterns were the same for roosting, foraging sites and the entire habitat. By contrast, P. s. comorensis has a relatively large geographic range that extends over low-elevation farmlands and villages and it was negatively correlated to natural forest across the entire area and all roosting sites, but its foraging areas were positively correlated to natural forest and high elevation areas. Both species selected large, tall trees for roosting. The total number of individuals in the studied area was estimated to be 1243 P. livingstonii and 11,898 P. s. comorensis. The results of our study demonstrated that these two species use different habitat types and ensure different ecosystem services in pollination and seed dispersion and thus are both critical for maintaining overall ecosystem dynamics. However, the currently high level of hunting pressure and roost disturbance makes them vulnerable to extinction. To ensure the viability of both species, conservation measures need to be taken by the Comoros government.

MEDICAL MANAGEMENT OF DILATED CARDIOMYOPATHY IN LIVINGSTONE FRUIT BATS ( PTEROPUS LIVINGSTONII).

Eleven cases of dilated cardiomyopathy have been diagnosed and treated in captive Livingstone fruit bats ( Pteropus livingstonii) in the United Kingdom over the past 7 yr. All but one case received treatment with a diuretic plus an angiotensin-converting enzyme inhibitor (ACEI), and, or pimobendan. One case is still under treatment with pimobendan alone, following diagnosis before onset of clinical signs. Diuretic treatment consisted of furosemide at a dose rate of 0.5-5 mg/kg, one to three times daily, and, or spironolactone at a dose rate of 1-4 mg/kg, once or twice daily. When used, the ACEI imidapril was given at a dose rate of 0.24-0.38 mg/kg q 24 hr, and pimobendan at a dose rate of 0.2-0.5 mg/kg bid. This report is intended to provide anyone seeking to medically manage heart failure in Pteropus species, particularly P. livingstonii, with a review of drugs and doses that have been used.

An exploratory investigation of echocardiographic parameters and the effects of posture on cardiac structure and function in the Livingstone's fruit bat (Pteropus livingstonii).

There is growing evidence that dilated cardiomyopathy may be a major cause of death in captive Livingstone's fruit bats (Pteropus livingstonii). Therefore, the primary aim of this prospective, exploratory study was to examine whether a systematic cardiac ultrasound protocol is feasible in this critically endangered species and to report basic measures of cardiac structure and function from a cohort of apparently healthy bats. A secondary aim was to test the effect posture (dorsal recumbency vs. roosting) has upon cardiac function in this species. Transthoracic echocardiograms, including 2D, Doppler, and tissue Doppler measures of cardiac structure and function were completed as part of routine health examinations for bats at a single center (n = 19). Bats were then grouped by age and disease status and the mean and range data reported for each group. In healthy adult bats, with the exception of a reduction in heart rate (P ≤0.05), right atrial systolic area (P ≤0.05), and right ventricular velocity during atrial contraction, there were no significant changes in cardiac structure or function in response to the roosting position. However, in the bats presenting with dilated cardiomyopathy the current data suggest that left ventricular ejection fraction is improved while roosting. Further work is required to confirm our initial findings, generate diagnostic reference intervals, and explore the causes of dilated cardiomyopathy in this species.

RADIOGRAPHIC CARDIAC SILHOUETTE MEASUREMENT IN CAPTIVE LIVINGSTONE'S FRUIT BATS (PTEROPUS LIVINGSTONII).

Cardiomyopathies have been increasingly noted in the captive population of Livingstone's fruit bat ( Pteropus livingstonii ). The aim of this study was to produce a set of repeatable quantitative reference measurements that could be used to assess the cardiac size during radiographic examination of this species. Ventro-dorsal and lateral radiographs (n = 129) from a total of 42 individual Livingstone's fruit bats were examined. The control group radiographs (n = 102) consisted of 34 healthy individuals. Radiographic measurements were taken of structures within the thorax and then converted into ratios. These ratios from radiographs (n = 27) were also calculated for eight individuals with diagnosed cardiomyopathy. Vertebral Heart Scores (VHS) were calculated from right lateral radiographs and compared between the two groups. From all the data, only the width of the cardiac silhouette to the width of the thorax (the W : T ratio) in the ventro-dorsal view and the VHS were found to be significantly different between both groups (P < 0.05). The group with cardiomyopathies had a mean W : T ratio of 0.59 (±0.005) and a VHS of 9.77 (±0.89), while a mean W : T ratio of 0.54 (±0.004) and a VHS of 8.71 (±0.93) was established for healthy specimens.