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David A Westcott - One of the best experts on this subject based on the ideXlab platform.
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Impacts of an invasive ant species on roosting behavior of an island endemic Flying‐Fox
Biotropica, 2019Co-Authors: Annabel Dorrestein, David A Westcott, Christopher M Todd, John M Martin, Justin A WelbergenAbstract:Introduced species can cause major disruptions to ecosystems, particularly on islands. On Christmas Island, the invasive yellow crazy ant (Anoplolepis gracilipes) has detrimental impacts on many animals ranging from the iconic red crabs (Gecarcoidea natalis) to the Christmas Island Thrush (Turdus poliocephalus erythropleurus). However, the full extent of its effects on the island's fauna is not yet known. In this study, we investigated the impact of the yellow crazy ants on the island's last native mammal: the Christmas Island Flying‐Fox (Pteropus natalis). This species has been described as a keystone species, but has recently experienced substantial population decline to the extent that it is now listed as Critically Endangered. We examined the impacts of the yellow crazy ants on the roosting behavior of the Christmas Island Flying‐Fox, and on its local and island‐wide distribution patterns. We showed that the crazy ants increased behaviors in the Flying‐Foxes that were associated with avoidance of noxious stimuli and decreased behaviors associated with resting. Roost tree selection and roost site location were not related to variation in the abundance of crazy ants on the island. Our results indicate that the crazy ants interfere with the activity budgets of the Flying‐Foxes. However, the Flying‐Foxes failed to relocate to ant‐free roost trees or roost sites when confronted with the noxious ant, suggesting that the Flying‐Foxes are either not sufficiently disturbed to override strong cultural attachment to roosts, or, are behaving maladaptively due to ecological naivete.
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impacts of an invasive ant species on roosting behavior of an island endemic Flying Fox
Biotropica, 2019Co-Authors: David A Westcott, Annabel Dorrestein, Christopher M Todd, John M Martin, Justin A WelbergenAbstract:Introduced species can cause major disruptions to ecosystems, particularly on islands. On Christmas Island, the invasive yellow crazy ant (Anoplolepis gracilipes) has detrimental impacts on many animals ranging from the iconic red crabs (Gecarcoidea natalis) to the Christmas Island Thrush (Turdus poliocephalus erythropleurus). However, the full extent of its effects on the island's fauna is not yet known. In this study, we investigated the impact of the yellow crazy ants on the island's last native mammal: the Christmas Island Flying‐Fox (Pteropus natalis). This species has been described as a keystone species, but has recently experienced substantial population decline to the extent that it is now listed as Critically Endangered. We examined the impacts of the yellow crazy ants on the roosting behavior of the Christmas Island Flying‐Fox, and on its local and island‐wide distribution patterns. We showed that the crazy ants increased behaviors in the Flying‐Foxes that were associated with avoidance of noxious stimuli and decreased behaviors associated with resting. Roost tree selection and roost site location were not related to variation in the abundance of crazy ants on the island. Our results indicate that the crazy ants interfere with the activity budgets of the Flying‐Foxes. However, the Flying‐Foxes failed to relocate to ant‐free roost trees or roost sites when confronted with the noxious ant, suggesting that the Flying‐Foxes are either not sufficiently disturbed to override strong cultural attachment to roosts, or, are behaving maladaptively due to ecological naivete.
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slow growth and delayed maturation in a critically endangered insular Flying Fox pteropus natalis
Journal of Mammalogy, 2018Co-Authors: Christopher M Todd, Karrie Rose, David A Westcott, John M Martin, Justin A WelbergenAbstract:: Flying Foxes (family Pteropodidae) have distinct life histories given their size, characterized by longevity, low reproductive output, and long gestation. However, they tend to decouple the age at which sexual maturity is reached from the age at which they reach adult dimensions. We examined growth, maturation, and reproduction in the Critically Endangered Christmas Island Flying Fox (Pteropus natalis) to determine the timing of sex-specific life cycle events and patterns of growth. We estimated that juvenile growth in forearm length and body mass increased at a mean rate of 0.029 ± 0.005 mm/day and 0.33 ± 0.07 g/day for both males and females alike. Using these growth rates, we determined that the birth of pups occurs between December and March, with young becoming volant between June and August. The age at maturation for P. natalis is one of the oldest among all bat species. Juvenile males began to mature 15 months after birth and reached maturity 27 months after birth. Females reached maturity 24 months after birth at a significantly smaller body mass (3.6%) and forearm length (1.4%) than males. Significant sexual dimorphism and bimaturation was observed, with juvenile males being 1.5% and adult males being 1.9% larger on average than females for skeletal dimensions only. Growth and maturation are even slower in P. natalis than in the few other Pteropus species studied to date. The slow growth and delayed maturation of P. natalis imply slower potential population growth rates, further complicating the recovery of this Critically Endangered single-island endemic.
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a state space modelling approach to wildlife monitoring with application to Flying Fox abundance
Scientific Reports, 2018Co-Authors: David A Westcott, Peter Caley, Daniel K Heersink, Adam MckeownAbstract:Monitoring Flying-Foxes is challenging as their extreme mobility produces highly dynamic population processes, considerable logistic difficulty, and variability in estimated population size. We report on methods for inferring population trend for the population of the spectacled Flying-Fox (Pteropus conspicillatus) in Australia. Monthly monitoring is conducted at all known roost sites across the species’ range in the Wet Tropics Region. The proportion of animals in camps varies seasonally and stochastic environmental events appear to be influential. We develop a state-space model that incorporates these processes and enables inference on total population trends and uses early warning analysis to identify the causes of population dynamics. The model suggests that population growth rate is stable in the absence of cyclones, however, cyclones appear to impact on both survival and reproduction. The population recovered after two cyclones but declined after a third. The modelling estimates a population decline over 15 years of c. 75% (mean r = − 0.12yr−1 and belief of negative trend is c. 83%) suggesting that conservation action is warranted. Our work shows that a state-space modelling approach is a significant improvement on inference from raw counts from surveys and demonstrates that this approach is a workable alternative to other methods.
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are Flying Foxes coming to town urbanisation of the spectacled Flying Fox pteropus conspicillatus in australia
PLOS ONE, 2014Co-Authors: Jessica Tait, Humberto L Perottobaldivieso, Adam Mckeown, David A WestcottAbstract:Urbanisation of wildlife populations is a process with significant conservation and management implications. While urban areas can provide habitat for wildlife, some urbanised species eventually come into conflict with humans. Understanding the process and drivers of wildlife urbanisation is fundamental to developing effective management responses to this phenomenon. In Australia, Flying-Foxes (Pteropodidae) are a common feature of urban environments, sometimes roosting in groups of tens of thousands of individuals. Flying-Foxes appear to be becoming increasingly urbanised and are coming into increased contact and conflict with humans. Flying-Fox management is now a highly contentious issue. In this study we used monitoring data collected over a 15 year period (1998–2012) to examine the spatial and temporal patterns of association of spectacled Flying-Fox (Pteropus conspicillatus) roost sites (camps) with urban areas. We asked whether spectacled Flying-Foxes are becoming more urbanised and test the hypothesis that such changes are associated with anthropogenic changes to landscape structure. Our results indicate that spectacled Flying-Foxes were more likely to roost near humans than might be expected by chance, that over the period of the study the proportion of the Flying-Foxes in urban-associated camps increased, as did the number of urban camps. Increased urbanisation of spectacled Flying-Foxes was not related to changes in landscape structure or to the encroachment of urban areas on camps. Overall, camps tended to be found in areas that were more fragmented, closer to human habitation and with more urban land cover than the surrounding landscape. This suggests that urbanisation is a behavioural response rather than driven by habitat loss.
John R Speakman - One of the best experts on this subject based on the ideXlab platform.
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soaring behaviour in the samoan Flying Fox pteropus samoensis
Journal of Zoology, 2006Co-Authors: S C Thomson, Anne P Brooke, John R SpeakmanAbstract:Bats seldom soar because it is behaviour generally associated with the use of thermals, which are normally of insufficient strength at night to support the behaviour. Daylight Flying bats, however, such as the Samoan Flying Fox Pteropus samoensis may be able to exploit thermals for soaring. This may give the bats one of two advantages. It may reduce the energy costs of transport because gliding flight is much cheaper than active flapping flight. However, because less endogenous heat is generated by soaring, a second advantage may be that it reduces the thermal stress placed on these bats. Thermal stress is a factor that we have shown previously probably constrains the daylight Flying behaviour of this species. Observations of the patterns of soaring behaviour at two sites on American Samoa in March and October 1995 supported the predictions of the energy saving but not the hyperthermia avoidance hypothesis. Soaring was a common behaviour under all conditions and was used extensively when conditions did not pose a threat of hyperthermia. In March, the bats also adopted flight patterns over time that exposed them to areas of the valleys where insolation was greatest, presumably increasing their risk of hyperthermia but bringing energy saving benefits. Modelling the expected heat flows during soaring and flapping flight using an established model revealed that soaring reduced the risk of hyperthermia, when Flying in the shade of clouds, because of the energy savings resulting from reduced endogenous heat production. However, when soaring in sunlight, these savings are more than offset by the increased exogenous heat uptake, because a greater proportion of the wing surface is exposed when soaring. Despite its low endogenous energy cost, soaring in sunlight is not thermally advantageous, and the behaviour of the bats reflected this fact.
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diurnal activity in the samoan Flying Fox pteropus samoensis
Philosophical Transactions of the Royal Society B, 1998Co-Authors: S C Thomson, Anne P Brooke, John R SpeakmanAbstract:Speakman and co-workers suggested the diurnal Samoan Flying Fox, Pteropus samoensis, may be at risk of hyperthermia when Flying during the day, particularly at high levels of insolation. We monitored activity of this bat and climate simultaneously at two different sites and four times of year in American Samoa. Flight activity varied significantly with time of day, between days, study sites and seasons. Out of the six data sets collected, the four with the highest mean levels of insolation showed a significant decrease in bat numbers with increasing temperature and sunlight. When each individual activity count was directly compared to the predictions of Speakman and co-workers' biophysical model, 85 to 95% of bat flight activity was found to be in conditions the model suggested would not pose a risk of hyperthermia. This supports the suggestion that in extreme conditions the animals would not fly as they risked overheating. The 5 to 15% of counts in which animals were seen to fly in conditions the model predicted they should not may be explained by erroneous assumptions underlying the model predictions.
M B Calford - One of the best experts on this subject based on the ideXlab platform.
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interhemispheric connections of somatosensory cortex in the Flying Fox
The Journal of Comparative Neurology, 1998Co-Authors: Leah Krubitzer, Janine C Clarey, Rowan Tweedale, M B CalfordAbstract:The interhemispheric connections of somatosensory cortex in the gray- headed Flying Fox (Pteropus poliocephalus) were examined. Injections of anatomical tracers were placed into five electrophysiologically identified somatosensory areas: the primary somatosensory area (SI or area 3b), the anterior parietal areas 3a and 1/2, and the lateral somatosensory areas SII (the secondary somatosensory area) and PV (pairetal ventral area). In two animals, the hemisphere opposite to that containing the injection sites was explored electrophysiologically to allow the details of the topography of interconnections to be assessed. Examination of the areal distribution of labeled cell bodies and/or axon terminals in cortex sectioned tangential to the pial surface revealed several consistent findings. First, the density of connections varied as a function of the body part representation injected. For example, the area 3b representation of the trunk and structures of the face are more densely interconnected than the representation of distal body parts (e.g., digit 1, D1). Second, callosal connections appear to be both matched and mismatched to the body part representations injected in the opposite hemisphere. For example, an injection of retrograde tracer into the trunk representation of area 3b revealed connections from the trunk representation in the opposite hemisphere, as well as from shoulder and forelimb/wing representations. Third, the same body part is differentially connected in different fields via the corpus callosum. For example, the D1 representation in area 3b in one hemisphere had no connections with the area 3b D1 representation in the opposite hemisphere, whereas the D1 representation in area 1/2 had relatively dense reciprocal connections with area 1/2 in the opposite hemisphere. Finally, there are callosal projections to fields other than the homotopic, contralateral field. For example, the D1 representation in area 1/2 projects to contralateral area 1/2, and also to area 3b and SII.
Michelle L. Baker - One of the best experts on this subject based on the ideXlab platform.
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seroprevalence of three paramyxoviruses hendra virus tioman virus cedar virus and a rhabdovirus australian bat lyssavirus in a range expanding fruit bat the grey headed Flying Fox pteropus poliocephalus
PLOS ONE, 2020Co-Authors: Wayne Boardman, Michelle L. Baker, Gary Crameri, Victoria Boyd, Grantley R Peck, Terry Reardon, Ian Smith, Charles G B Caraguel, Thomas A A ProwseAbstract:Habitat-mediated global change is driving shifts in species’ distributions which can alter the spatial risks associated with emerging zoonotic pathogens. Many emerging infectious pathogens are transmitted by highly mobile species, including bats, which can act as spill-over hosts for pathogenic viruses. Over three years, we investigated the seroepidemiology of paramyxoviruses and Australian bat lyssavirus in a range-expanding fruit bat, the Grey-headed Flying Fox (Pteropus poliocephalus), in a new camp in Adelaide, South Australia. Over six, biannual, sampling sessions, we quantified median florescent intensity (MFI) antibody levels for four viruses for a total of 297 individual bats using a multiplex Luminex binding assay. Where appropriate, florescence thresholds were determined using finite mixture modelling to classify bats’ serological status. Overall, apparent seroprevalence of antibodies directed at Hendra, Cedar and Tioman virus antigens was 43.2%, 26.6% and 95.7%, respectively. We used hurdle models to explore correlates of seropositivity and antibody levels when seropositive. Increased body condition was significantly associated with Hendra seropositivity (Odds ratio = 3.67; p = 0.002) and Hendra virus levels were significantly higher in pregnant females (p = 0.002). While most bats were seropositive for Tioman virus, antibody levels for this virus were significantly higher in adults (p < 0.001). Unexpectedly, all sera were negative for Australian bat lyssavirus. Temporal variation in antibody levels suggests that antibodies to Hendra virus and Tioman virus may wax and wane on a seasonal basis. These findings suggest a common exposure to Hendra virus and other paramyxoviruses in this Flying Fox camp in South Australia.
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Disease Risk Perception and Safety Practices: A Survey of Australian Flying Fox Rehabilitators.
PLOS Neglected Tropical Diseases, 2016Co-Authors: Cecilia A. Sánchez, Michelle L. BakerAbstract:Interactions with Flying Foxes pose disease transmission risks to volunteer rehabilitators (carers) who treat injured, ill, and orphaned bats. In particular, Australian bat lyssavirus (ABLV) can be transmitted directly from Flying Foxes to humans in Australia. Personal protective equipment (PPE) and rabies vaccination can be used to protect against lyssavirus infection. During May and June 2014, active Australian Flying Fox carers participated in an online survey (SOAR: Survey Of Australian Flying Fox Rehabilitators) designed to gather demographic data, assess perceptions of disease risk, and explore safety practices. Responses to open-ended questions were analysed thematically. A logistic regression was performed to assess whether rehabilitators’ gender, use of PPE, threat perception, and years of experience predicted variation in their odds of being bitten or scratched. Eligible responses were received from 122 rehabilitators located predominantly on the eastern coast of Australia. Eighty-four percent of respondents were female. Years of experience ranged from
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disease risk perception and safety practices a survey of australian Flying Fox rehabilitators
PLOS Neglected Tropical Diseases, 2016Co-Authors: Cecilia A. Sánchez, Michelle L. BakerAbstract:Interactions with Flying Foxes pose disease transmission risks to volunteer rehabilitators (carers) who treat injured, ill, and orphaned bats. In particular, Australian bat lyssavirus (ABLV) can be transmitted directly from Flying Foxes to humans in Australia. Personal protective equipment (PPE) and rabies vaccination can be used to protect against lyssavirus infection. During May and June 2014, active Australian Flying Fox carers participated in an online survey (SOAR: Survey Of Australian Flying Fox Rehabilitators) designed to gather demographic data, assess perceptions of disease risk, and explore safety practices. Responses to open-ended questions were analysed thematically. A logistic regression was performed to assess whether rehabilitators’ gender, use of PPE, threat perception, and years of experience predicted variation in their odds of being bitten or scratched. Eligible responses were received from 122 rehabilitators located predominantly on the eastern coast of Australia. Eighty-four percent of respondents were female. Years of experience ranged from <1 to 30 years (median 5 years). Respondents were highly educated. All rehabilitators were vaccinated against rabies and 94% received a rabies titre check at least every two years. Sixty-three percent of carers did not perceive viruses in Flying Foxes as a potential threat to their health, yet 74% of carers reported using PPE when handling Flying Foxes. Eighty-three percent of rehabilitators had received a Flying Fox bite or scratch at some point during their career. Carers provide an important community service by rescuing and rehabilitating Flying Foxes. While rehabilitators in this study have many excellent safety practices, including a 100% vaccination rate against rabies, there is room for improvement in PPE use. We recommend 1) the establishment of an Australia-wide set of guidelines for safety when caring for bats and 2) that the responsible government agencies in Australia support carers who rescue potentially ABLV-infected bats by offering compensation for PPE.
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the immune gene repertoire of an important viral reservoir the australian black Flying Fox
BMC Genomics, 2012Co-Authors: Michelle L. Baker, Anthony T Papenfuss, Zhiping Feng, Mary Tachedjian, Gary Crameri, Christopher Cowled, Justin H J NgAbstract:Background Bats are the natural reservoir host for a range of emerging and re-emerging viruses, including SARS-like coronaviruses, Ebola viruses, henipaviruses and Rabies viruses. However, the mechanisms responsible for the control of viral replication in bats are not understood and there is little information available on any aspect of antiviral immunity in bats. Massively parallel sequencing of the bat transcriptome provides the opportunity for rapid gene discovery. Although the genomes of one megabat and one microbat have now been sequenced to low coverage, no transcriptomic datasets have been reported from any bat species. In this study, we describe the immune transcriptome of the Australian Flying Fox, Pteropus alecto, providing an important resource for identification of genes involved in a range of activities including antiviral immunity.
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molecular characterisation of toll like receptors in the black Flying Fox pteropus alecto
Developmental and Comparative Immunology, 2011Co-Authors: Christopher Cowled, Linfa Wang, Michelle L. Baker, Mary Tachedjian, Peng Zhou, Dieter M BulachAbstract:Abstract Bats are believed to be reservoir hosts for a number of emerging and re-emerging viruses, many of which are responsible for illness and mortality in humans, livestock and other animals. In other vertebrates, early responses to viral infection involve engagement of Toll-like receptors (TLRs), which induce changes in gene expression collectively leading to an “antiviral state”. In this study we report the cloning and bioinformatic analysis of a complete set of TLRs from the black Flying Fox Pteropus alecto , and perform quantitative tissue expression analysis of the nucleic acid-sensing TLRs 3, 7, 8 and 9. Full-length mRNA transcripts from TLRs homologous to human TLRs 1–10 were sequenced, as well as a nearly intact TLR13 pseudogene that was spliced and polyadenylated. This prototype data can now be used to design functional studies of the bat innate immune system.
Anne P Brooke - One of the best experts on this subject based on the ideXlab platform.
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soaring behaviour in the samoan Flying Fox pteropus samoensis
Journal of Zoology, 2006Co-Authors: S C Thomson, Anne P Brooke, John R SpeakmanAbstract:Bats seldom soar because it is behaviour generally associated with the use of thermals, which are normally of insufficient strength at night to support the behaviour. Daylight Flying bats, however, such as the Samoan Flying Fox Pteropus samoensis may be able to exploit thermals for soaring. This may give the bats one of two advantages. It may reduce the energy costs of transport because gliding flight is much cheaper than active flapping flight. However, because less endogenous heat is generated by soaring, a second advantage may be that it reduces the thermal stress placed on these bats. Thermal stress is a factor that we have shown previously probably constrains the daylight Flying behaviour of this species. Observations of the patterns of soaring behaviour at two sites on American Samoa in March and October 1995 supported the predictions of the energy saving but not the hyperthermia avoidance hypothesis. Soaring was a common behaviour under all conditions and was used extensively when conditions did not pose a threat of hyperthermia. In March, the bats also adopted flight patterns over time that exposed them to areas of the valleys where insolation was greatest, presumably increasing their risk of hyperthermia but bringing energy saving benefits. Modelling the expected heat flows during soaring and flapping flight using an established model revealed that soaring reduced the risk of hyperthermia, when Flying in the shade of clouds, because of the energy savings resulting from reduced endogenous heat production. However, when soaring in sunlight, these savings are more than offset by the increased exogenous heat uptake, because a greater proportion of the wing surface is exposed when soaring. Despite its low endogenous energy cost, soaring in sunlight is not thermally advantageous, and the behaviour of the bats reflected this fact.
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threats from overhunting to the Flying Fox pteropus tonganus chiroptera pteropodidae on niue island south pacific ocean
Biological Conservation, 2002Co-Authors: Anne P Brooke, Marco TschapkaAbstract:Abstract Flying Fox fruit bats are hunted in an annual 2-month season in Niue, a small and isolated South Pacific island nation. The sustainability of this hunt has been questioned because of an obvious recent decline. We estimated the island-wide Flying Fox population to be between 2040 and 4080 bats, 2 months prior to the 1998–1999 hunt. Sixty hunters interviewed after the hunt had shot 1555 bats, an unsustainable number. Many Niueans believe that an infinite quantity of Flying Foxes live in two small taboo or forbidden areas that originally acted as wildlife sanctuaries to safeguard animal resources for times of famine. However, our surveys suggest only a small colony roosts in one taboo area. Niueans' belief that taboo areas shelter an unlimited number of bats cannot be refuted as the areas may not be visited. Consequently, few people believe that the population is being overharvested.
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diurnal activity in the samoan Flying Fox pteropus samoensis
Philosophical Transactions of the Royal Society B, 1998Co-Authors: S C Thomson, Anne P Brooke, John R SpeakmanAbstract:Speakman and co-workers suggested the diurnal Samoan Flying Fox, Pteropus samoensis, may be at risk of hyperthermia when Flying during the day, particularly at high levels of insolation. We monitored activity of this bat and climate simultaneously at two different sites and four times of year in American Samoa. Flight activity varied significantly with time of day, between days, study sites and seasons. Out of the six data sets collected, the four with the highest mean levels of insolation showed a significant decrease in bat numbers with increasing temperature and sunlight. When each individual activity count was directly compared to the predictions of Speakman and co-workers' biophysical model, 85 to 95% of bat flight activity was found to be in conditions the model suggested would not pose a risk of hyperthermia. This supports the suggestion that in extreme conditions the animals would not fly as they risked overheating. The 5 to 15% of counts in which animals were seen to fly in conditions the model predicted they should not may be explained by erroneous assumptions underlying the model predictions.