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.

Population trends in the vulnerable Grey-headed flying-fox, Pteropus poliocephalus; results from a long-term, range-wide study

Monitoring is necessary for the management of any threatened species if its predicament and status are to improve. Monitoring establishes baseline data for tracking trends in distribution and abundance and is a key tool for informing threatened species management. Across much of the Old World, bats in the genus Pteropus (Pteropodidae, Chiroptera) face significant threats from habitat loss, conflict with humans, and hunting. Despite conflict with humans and their threatened status, few Pteropus are being monitored. Often, this is because of difficulties associated with their high mobility, large and easily disturbed aggregations, and their use of unknown or remote habitat. Here we describe 10 years of results from the National Flying-fox Monitoring Program (NFFMP) for the grey-headed flying-fox, (Pteropus poliocephalus) in Australia. Range-wide quarterly surveys were conducted over a three-day period since November 2012 using standardized methods appropriate to conditions encountered at each roost. For our analysis of the population and its trend, we used a state-space model to account for the ecology of the grey-headed flying-fox and the errors associated with the surveying process. Despite the general perception that the species is in decline, our raw data and the modelled population trend suggest the grey-headed flying-fox population has remained stable during the NFFMP period, with the range also stable. These results indicate that the species' extreme mobility and broad diet bestow it with a high level of resilience to various disturbance events. Long-term, range-wide studies such as this one, are crucial for understanding relatively long-lived and highly nomadic species such as the grey-headed flying-fox. The outcomes of this study highlight the need for such systematic population monitoring of all threatened Pteropus species.

Reproduction, seasonal morphology, and juvenile growth in three Malagasy fruit bats

The island nation of Madagascar is home to three endemic species of Old World fruit bat in the family Pteropodidae: Pteropus rufus, Eidolon dupreanum, and Rousettus madagascariensis, all three of which are IUCN Red Listed under some category of threat. Delineation of seasonal limits in the reproductive calendar for threatened mammals can inform conservation efforts by clarifying parameters used in population viability models, as well as elucidate understanding of the mechanisms underpinning pathogen persistence in host populations. Here, we define the seasonal limits of a staggered annual birth pulse across the three species of endemic Madagascar fruit bat, known reservoirs for viruses of high zoonotic potential. Our field studies indicate that this annual birth pulse takes place in September/October for P. rufus, November for E. dupreanum, and December for R. madagascariensis in central-eastern Madagascar where the bulk of our research was concentrated. Juvenile development periods vary across the three Malagasy pteropodids, resulting in near-synchronous weaning of pups for all species in late January-February at the height of the fruiting season for this region. We here document the size range in morphological traits for the three Malagasy fruit bat species, with P. rufus and E. dupreanum among the larger of pteropodids globally and R. madagascariensis among the smaller. All three species demonstrate subtle sexual dimorphism with males being larger than females. We explore seasonal variation in adult body condition by comparing observed body mass with body mass predicted by forearm length, demonstrating that pregnant females add weight during staggered gestation periods and males lose weight during the nutritionally deficit Malagasy winter. Finally, we quantify forearm, tibia, and ear length growth rates in juvenile bats, demonstrating both faster growth and more protracted development times for P. rufus as compared with E. dupreanum and R. madagascariensis. The longer development period for the already-threatened P. rufus further undermines the conservation status of this species as human hunting is particularly detrimental to population viability during reproductive periods. Our work highlights the importance of longitudinal field studies in collecting critical data for mammalian conservation efforts and human public health alike.

Make flying-fox hunting sustainable again: Comparing expected demographic effectiveness and hunters' acceptance of more restrictive regulations

Hunting is a major threat to many species of wildlife. However, managing hunting systems to ensure their sustainability requires a thorough demographic knowledge about the impact of hunting. Here we develop a framework integrating ecological, modelling and sociological data to achieve a sustainability assessment of flying-fox hunting in New Caledonia and assess the relative merits of alternative management policies. Using age-specific stochastic population models, we found that the current annual hunting rate [5.5-8.5%] is likely to lead to a severe decline (- 79%) of Pteropus populations over the next 30 years. However, a majority of hunters surveyed (60%) were willing to soften their practices, offering an opportunity for adaptive management. Recurrent temporary hunting ban (at least 1 year out of 2) in combination with protected areas (≥ 25%) appears as the most effective and most accepted management option. Our integrative approach appears to be a promising method for ensuring that traditional hunting systems can remain sustainable in a rapidly changing world.

Human-modified landscapes provide key foraging areas for a threatened flying mammal: The grey-headed flying-fox

Urban expansion is a major threat to natural ecosystems but also creates novel opportunities that adaptable species can exploit. The grey-headed flying-fox (Pteropus poliocephalus) is a threatened, highly mobile species of bat that is increasingly found in human-dominated landscapes, leading to many management and conservation challenges. Flying-fox urbanisation is thought to be a result of diminishing natural foraging habitat or increasing urban food resources, or both. However, little is known about landscape utilisation of flying-foxes in human-modified areas, and how this may differ in natural areas. Here we examine positional data from 98 satellite-tracked P. poliocephalus for up to 5 years in urban and non-urban environments, in relation to vegetation data and published indices of foraging habitat quality. Our findings indicate that human-modified foraging landscapes sustain a large proportion of the P. poliocephalus population year-round. When individuals roosted in non-urban and minor-urban areas, they relied primarily on wet and dry sclerophyll forest, forested wetlands, and rainforest for foraging, and preferentially visited foraging habitat designated as high-quality. However, our results highlight the importance of human-modified foraging habitats throughout the species' range, and particularly for individuals that roosted in major-urban environments. The exact plant species that exist in human-modified habitats are largely undocumented; however, where this information was available, foraging by P. poliocephalus was associated with different dominant plant species depending on whether individuals roosted in 'urban' or 'non-urban' areas. Overall, our results demonstrate clear differences in urban- and non-urban landscape utilisation by foraging P. poliocephalus. However, further research is needed to understand the exact foraging resources used, particularly in human-modified habitats, and hence what attracts flying-foxes to urban areas. Such information could be used to modify the urban foraging landscape, to assist long-term habitat management programs aimed at minimising human-wildlife conflict and maximising resource availability within and outside of urban environments.

Conventional wisdom on roosting behavior of Australian flying-foxes-A critical review, and evaluation using new data

Fruit bats (Family: Pteropodidae) are animals of great ecological and economic importance, yet their populations are threatened by ongoing habitat loss and human persecution. A lack of ecological knowledge for the vast majority of Pteropodid species presents additional challenges for their conservation and management.In Australia, populations of flying-fox species (Genus: Pteropus) are declining and management approaches are highly contentious. Australian flying-fox roosts are exposed to management regimes involving habitat modification, through human-wildlife conflict management policies, or vegetation restoration programs. Details on the fine-scale roosting ecology of flying-foxes are not sufficiently known to provide evidence-based guidance for these regimes, and the impact on flying-foxes of these habitat modifications is poorly understood.We seek to identify and test commonly held understandings about the roosting ecology of Australian flying-foxes to inform practical recommendations and guide and refine management practices at flying-fox roosts.We identify 31 statements relevant to understanding of flying-fox roosting structure and synthesize these in the context of existing literature. We then contribute a contemporary, fine-scale dataset on within-roost structure to further evaluate 11 of these statements. The new dataset encompasses 13-monthly repeat measures from 2,522 spatially referenced roost trees across eight sites in southeastern Queensland and northeastern New South Wales.We show evidence of sympatry and indirect competition between species, including spatial segregation of black and grey-headed flying-foxes within roosts and seasonal displacement of both species by little red flying-foxes. We demonstrate roost-specific annual trends in occupancy and abundance and provide updated demographic information including the spatial and temporal distributions of males and females within roosts.Insights from our systematic and quantitative study will be important to guide evidence-based recommendations on restoration and management and will be crucial for the implementation of priority recovery actions for the preservation of these species in the future.

Gonzalez. Understanding human-flying fox interactions in the Agusan Marsh Wildlife Sanctuary as basis for conservation policy interventions

There is no documented flying fox hunting study done in the Agusan Marsh Wildlife Sanctuary (AMWS) which is known to harbor many threatened wildlife species. The Large Flying Fox Pteropus vampyrus is known to be threatened by hunting in the AMWS despite existing laws, such as the Wildlife Act. We conducted semi-structured interviews from September 2017 to January 2018 with 240 hunters in 10 villages through purposive sampling to determine the socio-demographic and economic profile of the hunters, their conservation awareness, perceptions on the monitoring scheme and enforcement, possible hunting patterns, and hunting drivers. Results showed that farming and fishing are the most common livelihoods of hunters. Most hunters achieved an education at the elementary level (42.9%), and belong to a household with 4–6 members (55.5%), often with only one member having a meager daily income (80.7%). Annual flooding was the main economic constraint to the hunters. Largely comprised of indigenous Manobos (62.9%), the majority of hunters did not believe in avoiding taboo species (85.4%). Most of the hunters were unaware of laws protecting Wildlife (62.9%) and unable to differentiate between threatened and non-threatened species (86.3%). Poor implementation of the monitoring scheme and insufficient enforcement were also observed in AMWS. Kites with hooks (55%) and guns (31.7%) were used to hunt P. vampyrus mostly for local consumption (83.3%). Multivariate analysis revealed that daily income and engagement in conservation negatively affected hunting intensity. With many constraints in totally banning hunting in poor and wildlife-dependent indigenous communities in AMWS, flexible policies must be considered. It is more reasonable and realistic to consider science-based hunting quotas in policy interventions to balance conservation and human welfare. Positive behavioral change towards sustainable hunting and trading bans requires a combination of effective education campaigns, engagement of indigenous communities in conservation, improved enforcement, and sustainable livelihood programs.

Spatial dynamics of pathogen transmission in communally roosting species: Impacts of changing habitats on bat-virus dynamics

The spatial organization of populations determines their pathogen dynamics. This is particularly important for communally roosting species, whose aggregations are often driven by the spatial structure of their environment.

We develop a spatially explicit model for virus transmission within roosts of Australian tree‐dwelling bats (Pteropus spp.), parameterized to reflect Hendra virus. The spatial structure of roosts mirrors three study sites, and viral transmission between groups of bats in trees was modelled as a function of distance between roost trees. Using three levels of tree density to reflect anthropogenic changes in bat habitats, we investigate the potential effects of recent ecological shifts in Australia on the dynamics of zoonotic viruses in reservoir hosts.

We show that simulated infection dynamics in spatially structured roosts differ from that of mean‐field models for equivalently sized populations, highlighting the importance of spatial structure in disease models of gregarious taxa. Under contrasting scenarios of flying‐fox roosting structures, sparse stand structures (with fewer trees but more bats per tree) generate higher probabilities of successful outbreaks, larger and faster epidemics, and shorter virus extinction times, compared to intermediate and dense stand structures with more trees but fewer bats per tree. These observations are consistent with the greater force of infection generated by structured populations with less numerous but larger infected groups, and may flag an increased risk of pathogen spillover from these increasingly abundant roost types.

Outputs from our models contribute insights into the spread of viruses in structured animal populations, like communally roosting species, as well as specific insights into Hendra virus infection dynamics and spillover risk in a situation of changing host ecology. These insights will be relevant for modelling other zoonotic viruses in wildlife reservoir hosts in response to habitat modification and changing populations, including coronaviruses like SARS‐CoV‐2.

Effects of Waning Maternal Immunity on Infection Dynamics in Seasonally Breeding Wildlife

Increasing outbreaks of emerging infectious diseases originating from wildlife have intensified interests in understanding their dynamics in reservoir hosts. The effect of waning maternally derived antibodies on epidemics in a seasonally breeding wild mammal population is unclear. We examined how the population structure, influenced by seasonal breeding and maternally derived immunity, affects viral invasion and persistence using a hypothetical system based on Hendra virus infection in black flying foxes (Pteropus alecto). A deterministic Hendra virus epidemic model with uncertainty in parameter values was used to simulate transient epidemics following viral introduction into an infection-free population, including various timings within a year and differences in pre-existing seroprevalence. Additionally, we applied different modelling methods of waning maternal immunity to examine whether different models notably affected modelling outputs. The waning of maternally derived immunity temporally dispersed the supply of susceptible individuals in seasonally breeding populations, diminishing the effect of birth pulses generating the temporally synchronised supply of susceptible newborns. Thus, even in a population with seasonal births, a considerable level of probabilities of viral invasion and persistence could occur no matter when infectious individuals were introduced into the population. Viral invasion and persistence were substantially influenced by the modelling method of maternally derived immunity, emphasising the need to select an appropriate method and further investigate the waning pattern of maternally derived antibodies.

Using Stochastic Modeling to Predict the Effect of Culling and Colony Dispersal of Bats on Zoonotic Viral Epidemics

Frequent outbreaks of emerging infectious diseases originating from wild animals have highlighted the necessity of managing wildlife populations to prevent zoonotic spillover, and the appropriate development of management protocols required attention on gaining a better understanding of viral dynamics in wild animal populations. In east Australia, there have been outbreaks of Hendra virus (HeV) infection in horses and humans following spillover from the virus's reservoir hosts, flying foxes (family Pteropodidae), and bat culling and colony dispersal have been proposed as appropriate management strategies. A key factor relating to flying fox population structure that influences HeV dynamics is that these bats form metapopulations, and consequently, to assess this factor, we designed an epidemic dynamics model of HeV transmission, focusing on bat metapopulation dynamics. Specifically, using flying fox movement data, we stochastically simulated models for a hypothetical metapopulation of flying foxes to examine the impact of metapopulation-related parameters, and subsequently simulated probable scenarios of culling and colony dispersal to estimate their effects on the probability of epidemic occurrence. Modeling of the hypothetical metapopulation revealed that a reduction in the number of large-sized colonies would lead to an increase in the probability of epidemic occurrence within the bat population, whereas the strong spatial coupling among colonies was found to dilute the effects of altering the number of colonies and the number of bats in each colony through culling or colony dispersal of bats on the probability that an epidemic within the bat population would occur. Culling and colony dispersal scenarios showed no significantly beneficial effect with respect to reducing the probability of an HeV epidemic occurring in flying foxes, and may indeed prove counterproductive. In conclusion, the modeling results indicate that bat culling and colony dispersal may not be an effective strategy to control HeV epidemics.

Urban Sprawl, Food Subsidies and Power Lines: An Ecological Trap for Large Frugivorous Bats in Sri Lanka?

Electrocution is one of the less known anthropogenic impacts likely affecting the bat population. We surveyed 925 km of overhead distribution power lines that supply energy to spreading urbanized areas in Sri Lanka, recording 300 electrocuted Indian flying foxes (Pteropus giganteus). Electrocutions were recorded up to 58 km from the nearest known colony, and all of them were in urbanized areas and very close ( X ¯ = 4.8 m) to the exotic fruiting trees cultivated in gardens. Predictable anthropogenic food subsidies, in the form of cultivated fruits and flowers, seem to attract flying foxes to urban habitats, which in turn become ecological traps given their high electrocution risk. However, electrocution rates greatly varied among the 352 power lines surveyed (0.00–24.6 indiv./km), being highest in power lines with four wires oriented vertically ( X ¯ = 0.92 indiv./km) and almost zero in power lines with wires oriented horizontally. Therefore, the latter design should be applied to projected new power lines and old vertically oriented lines in electrocution hotspots should be substituted. Given that flying foxes are key seed dispersers and pollinators, their foraging habitat selection change toward urban habitats together with high electrocution risk not only may contribute to their population decline but also put their ecosystem services at risk.

Monitoring hunted species of cultural significance: Estimates of trends, population sizes and harvesting rates of flying-fox (Pteropus sp.) in New Caledonia

Assessing population trends and their underlying factors is critical to propose efficient conservation actions. This assessment can be particularly challenging when dealing with highly mobile, shy and nocturnal animals such as flying-foxes. Here we investigated the dynamics of hunted populations of Pteropus ornatus and P. tonganus in the Northern Province of New Caledonia. First, an ethno-ecological survey involving 219 local experts identified 494 flying-fox roosts. Current status was assessed for 379 of them, among which 125 were no longer occupied, representing a loss of 33% over ca. 40 years. Second, species-specific counts conducted at 35 roosts, and a sample of animals killed by hunters, revealed that the endemic species, P. ornatus, was dominant (68.5%). Between 2010 and 2016, 30 roosts were counted annually during the pre-parturition period. Roosts size averaged 1,425 ± 2,151 individuals (N = 180 counts) and showed high among-year variations (roost-specific CV = 37-162%). If we recorded significant inter-annual variation, we did not detect a significant decline over the 7-yr period, although one roost went possibly extinct. Population size of the two species combined was estimated at 338,000-859,000 individuals distributed over ca. 400 roosts in the Northern Province. Flying-foxes are popular game species and constitute traditional food for all communities of New Caledonia. Annual bags derived from a food survey allowed us to estimate harvesting rates at 5-14%. Such a level of harvesting for species with a 'slow' demography, the occurrence of poaching and illegal trade, suggest the current species use might not be sustainable and further investigations are critically needed.

Population genetics of fruit bat reservoir informs the dynamics, distribution and diversity of Nipah virus

The structure and connectivity of wildlife host populations may influence zoonotic disease dynamics, evolution and therefore spillover risk to people. Fruit bats in the genus Pteropus, or flying foxes, are the primary natural reservoir for henipaviruses-a group of emerging paramyxoviruses that threaten livestock and public health. In Bangladesh, Pteropus medius is the reservoir for Nipah virus-and viral spillover has led to human fatalities nearly every year since 2001. Here, we use mitochondrial DNA and nuclear microsatellite markers to measure the population structure, demographic history and phylogeography of P. medius in Bangladesh. We combine this with a phylogeographic analysis of all known Nipah virus sequences and strains currently available to better inform the dynamics, distribution and evolutionary history of Nipah virus. We show that P. medius is primarily panmictic, but combined analysis of microsatellite and morphological data shows evidence for differentiation of two populations in eastern Bangladesh, corresponding to a divergent strain of Nipah virus also found in bats from eastern Bangladesh. Our demographic analyses indicate that a large, expanding population of flying foxes has existed in Bangladesh since the Late Pleistocene, coinciding with human population expansion in South Asia, suggesting repeated historical spillover of Nipah virus likely occurred. We present the first evidence of mitochondrial introgression, or hybridization, between P. medius and flying fox species found in South-East Asia (P. vampyrus and P. hypomelanus), which may help to explain the distribution of Nipah virus strains across the region.

Population trends for two Malagasy fruit bats

Madagascar is home to three endemic species of Old World Fruit Bat, which are important pollinators and seed dispersers. We aimed to quantitatively assess population trajectories for the two largest of these species, the IUCN-listed 'Vulnerable' Eidolon dupreanum and Pteropus rufus. To this end, we conducted a longitudinal field study, in which we live-captured E. dupreanum and P. rufus, estimated species-specific fecundity rates, and generated age-frequency data via histological analysis of cementum annuli layering in tooth samples extracted from a subset of individuals. We fit exponential models to resulting data to estimate annual survival probabilities for adult bats (s _A = .794 for E. dupreanum; s _A = .511 for P. rufus), then applied Lefkovitch modeling techniques to infer the minimum required juvenile survival rate needed to permit longterm population persistence. Given estimated adult survival, population persistence was only possible for E. dupreanum when field-based fecundity estimates were replaced by higher values reported in the literature for related species. For P. rufus, tooth-derived estimates of adult survival were so low that even assumptions of perfect (100%) juvenile annual survival would not permit stable population trajectories. Age-based survival analyses were further supported by longitudinal exit counts carried out from 2013-2018 at three local P. rufus roost sites, which demonstrated a statistically significant, faintly negative time trend, indicative of subtle regional population declines. These results suggest that Malagasy fruit bat species face significant threats to population viability, with P. rufus particularly imperiled. Immediate conservation interventions, including habitat restoration and cessation of legally sanctioned bat hunting, are needed to protect Madagascar's fruit bats into the future.

Slow growth and delayed maturation in a Critically Endangered insular flying fox (Pteropus natalis)

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.

Can survival analyses detect hunting pressure in a highly connected species? Lessons from straw-coloured fruit bats

Animal behaviour, social structure and population dynamics affect community structure, interspecific interactions, and a species' resilience to harvesting. Building on new life history information for the straw-coloured fruit bat (Eidolon helvum) from multiple localities across Africa, we used survival analyses based on tooth-cementum annuli data to test alternative hypotheses relating to hunting pressure, demography and population connectivity. The estimated annual survival probability across Africa was high (≥ 0.64), but was greatest in colonies with the highest proportion of males. This difference in sex survival, along with age and sex capture biases and out-of-phase breeding across the species' distribution, leads us to hypothesize that E. helvum has a complex social structure. We found no evidence for additive mortality in heavily hunted populations, with most colonies having high survival with constant risk of mortality despite different hunting pressure. Given E. helvum's slow life history strategy, similar survival patterns and rate among colonies suggest that local movement and regional migration may compensate for local excess hunting, but these were also not clearly detected. Our study suggests that spatio-temporal data are necessary to appropriately assess the population dynamics and conservation status of this and other species with similar traits.

Bat Hunting and Bat-Human Interactions in Bangladeshi Villages: Implications for Zoonotic Disease Transmission and Bat Conservation

Bats are an important reservoir for emerging zoonotic pathogens. Close human–bat interactions, including the sharing of living spaces and hunting and butchering of bats for food and medicines, may lead to spillover of zoonotic disease into human populations. We used bat exposure and environmental data gathered from 207 Bangladeshi villages to characterize bat exposures and hunting in Bangladesh. Eleven percent of households reported having a bat roost near their homes, 65% reported seeing bats flying over their households at dusk, and 31% reported seeing bats inside their compounds or courtyard areas. Twenty percent of households reported that members had at least daily exposure to bats. Bat hunting occurred in 49% of the villages surveyed and was more likely to occur in households that reported nearby bat roosts (adjusted prevalence ratio [aPR] 2.3, 95% CI 1.1–4.9) and villages located in north‐west (aPR 7.5, 95% CI 2.5–23.0) and south‐west (aPR 6.8, 95% CI 2.1–21.6) regions. Our results suggest high exposure to bats and widespread hunting throughout Bangladesh. This has implications for both zoonotic disease spillover and bat conservation.

Recrudescent infection supports Hendra virus persistence in Australian flying-fox populations

Zoonoses from wildlife threaten global public health. Hendra virus is one of several zoonotic viral diseases that have recently emerged from Pteropus species fruit-bats (flying-foxes). Most hypotheses regarding persistence of Hendra virus within flying-fox populations emphasize horizontal transmission within local populations (colonies) via urine and other secretions, and transmission among colonies via migration. As an alternative hypothesis, we explore the role of recrudescence in persistence of Hendra virus in flying-fox populations via computer simulation using a model that integrates published information on the ecology of flying-foxes, and the ecology and epidemiology of Hendra virus. Simulated infection patterns agree with infection patterns observed in the field and suggest that Hendra virus could be maintained in an isolated flying-fox population indefinitely via periodic recrudescence in a manner indistinguishable from maintenance via periodic immigration of infected individuals. Further, post-recrudescence pulses of infectious flying-foxes provide a plausible basis for the observed seasonal clustering of equine cases. Correct understanding of the infection dynamics of Hendra virus in flying-foxes is fundamental to effectively managing risk of infection in horses and humans. Given the lack of clear empirical evidence on how the virus is maintained within populations, the role of recrudescence merits increased attention.

Tick paralysis in spectacled flying-foxes (Pteropus conspicillatus) in North Queensland, Australia: impact of a ground-dwelling ectoparasite finding an arboreal host

When a parasite finds a new wildlife host, impacts can be significant. In the late 1980s populations of Spectacled Flying-foxes (SFF) (Pteropus conspicillatus), a species confined, in Australia, to north Queensland became infected by paralysis tick (Ixodes holocyclus), resulting in mortality. This Pteropus-tick relationship was new to Australia. Curiously, the relationship was confined to several camps on the Atherton Tableland, north Queensland. It was hypothesised that an introduced plant, wild tobacco (Solanum mauritianum), had facilitated this new host-tick interaction. This study quantifies the impact of tick paralysis on SFF and investigates the relationship with climate. Retrospective analysis was carried out on records from the Tolga Bat Hospital for 1998–2010. Juvenile mortality rates were correlated to climate data using vector auto-regression. Mortality rates due to tick paralysis ranged between 11.6 per 10,000 bats in 2003 and 102.5 in 2009; more female than male adult bats were affected. Juvenile mortality rates were negatively correlated with the total rainfall in January to March and July to September of the same year while a positive correlation of these quarterly total rainfalls existed with the total population. All tick affected camps of SFF were located in the 80% core range of S. mauritianum. This initial analysis justifies further exploration of how an exotic plant might alter the relationship between a formerly ground-dwelling parasite and an arboreal host.

Urban habituation, ecological connectivity and epidemic dampening: the emergence of Hendra virus from flying foxes (Pteropus spp.)

Anthropogenic environmental change is often implicated in the emergence of new zoonoses from wildlife; however, there is little mechanistic understanding of these causal links. Here, we examine the transmission dynamics of an emerging zoonotic paramyxovirus, Hendra virus (HeV), in its endemic host, Australian Pteropus bats (fruit bats or flying foxes). HeV is a biosecurity level 4 (BSL-4) pathogen, with a high case-fatality rate in humans and horses. With models parametrized from field and laboratory data, we explore a set of probable contributory mechanisms that explain the spatial and temporal pattern of HeV emergence; including urban habituation and decreased migration-two widely observed changes in flying fox ecology that result from anthropogenic transformation of bat habitat in Australia. Urban habituation increases the number of flying foxes in contact with human and domestic animal populations, and our models suggest that, in addition, decreased bat migratory behaviour could lead to a decline in population immunity, giving rise to more intense outbreaks after local viral reintroduction. Ten of the 14 known HeV outbreaks occurred near urbanized or sedentary flying fox populations, supporting these predictions. We also demonstrate that by incorporating waning maternal immunity into our models, the peak modelled prevalence coincides with the peak annual spill-over hazard for HeV. These results provide the first detailed mechanistic framework for understanding the sporadic temporal pattern of HeV emergence, and of the urban/peri-urban distribution of HeV outbreaks in horses and people.

Climate change and the effects of temperature extremes on Australian flying-foxes

Little is known about the effects of temperature extremes on natural systems. This is of increasing concern now that climate models predict dramatic increases in the intensity, duration and frequency of such extremes. Here we examine the effects of temperature extremes on behaviour and demography of vulnerable wild flying-foxes (Pteropus spp.). On 12 January 2002 in New South Wales, Australia, temperatures exceeding 42 degrees C killed over 3500 individuals in nine mixed-species colonies. In one colony, we recorded a predictable sequence of thermoregulatory behaviours (wing-fanning, shade-seeking, panting and saliva-spreading, respectively) and witnessed how 5-6% of bats died from hyperthermia. Mortality was greater among the tropical black flying-fox, Pteropus alecto (10-13%) than the temperate grey-headed flying-fox, Pteropus poliocephalus (less than 1%), and young and adult females were more affected than adult males (young, 23-49%; females, 10-15%; males, less than 3%). Since 1994, over 30000 flying-foxes (including at least 24500 P. poliocephalus) were killed during 19 similar events. Although P. alecto was relatively less affected, it is currently expanding its range into the more variable temperature envelope of P. poliocephalus, which increases the likelihood of die-offs occurring in this species. Temperature extremes are important additional threats to Australian flying-foxes and the ecosystem services they provide, and we recommend close monitoring of colonies where temperatures exceeding 42.0 degrees C are predicted. The effects of temperature extremes on flying-foxes highlight the complex implications of climate change for behaviour, demography and species survival.

Demographic indications of decline in the spectacled flying fox (Pteropus conspicillatus) on the Atherton Tablelands of northern Queensland

A lack of information about the spectacled flying fox (Pteropus conspicillatus) makes management and conservation of this vulnerable species difficult. The analysis of population dynamics using life-history traits and life tables is widely used in planning for the conservation and management of wildlife. In the present study, the first life table for any species of bat is provided and age estimates derived from counts of annual increments in tooth cementum rings are used to assess population trends and life-history traits in the spectacled flying fox on the Atherton Tablelands in north Queensland. As a result of high mortality, longevity was much shorter than expected from a theoretical basis. Life-table analyses suggest that the population experienced a 16% decrease during the 2 years of study. Absence of extended longevity to compensate for low reproductive output and delayed sexual maturity in ‘slow end’ mammal species such as P. conspicillatus reduces the window of opportunity for females to reproduce and adapt to changes in mortality rates. This study suggests that spectacled flying fox populations are sensitive to increased mortality and that reducing mortality rates should be the primary goal in conservation planning for P. conspicillatus.

Intensive hunting of large flying foxes Pteropus vampyrus natunae in Central Kalimantan, Indonesian Borneo

Pteropus vampyrus natunae, the Bornean subspecies of the large flying fox, has important roles in pollination but unsustainable hunting has been reported in Malaysian states. We provide the first description of hunting techniques and intensity in Indonesian Borneo. In forests around Palangka Raya this species is captured in canopy-level nets to support trade in the provincial capital. We estimate that in 2003 4,500 individuals were extracted from a single location in 30 days, which, together with trends reported in interviews with hunters and traders, suggests that hunting in this region is intensive and probably causing severe population declines. Further surveys are needed throughout Kalimantan to determine if this trend is occurring around other cities and whether intervention is needed to safeguard viable populations.

Observer error in exit counts of flying-foxes (Pteropus spp.)

Population estimation and monitoring is a fundamental component in the conservation management of any species. For species such as flying-foxes (Pteropus spp.) population estimation is complicated by the large number of animals involved, their mobility and the conditions under which counts are conducted. Because count results are used in the determination of management requirements, they are the focus of much critical attention. Despite this, while measures of the precision of fly-out counts of Pteropus spp. have been published, measures of their accuracy have not. In this paper we present an assessment of the accuracy and precision of observer counts of dusk fly-outs by comparing recordings of observers’ counts with a video of the same fly-out. Observer’s counts were significantly related to the video-count (rs = 0.69, P < 0.0001), with the average observer’s count underestimating the video-count by 14.7% (± 25, s.d.) of the video-count. Observers’ errors increased with the rate at which flying-foxes left the camp and with the width of the fly-out stream. These results suggest that while observers’ errors are inherent in dusk fly-out counts, these errors are manageable and relatively predictable. Other sources of error are likely to have a greater impact on the final population estimate at both camp and regional scales.