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 nonurban 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 nonurban 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

Variety is the spice of life : flying-foxes exploit a variety of native and exotic food plants in an urban landscape mosaic

Generally, urbanization is a major threat to biodiversity; however, urban areas also provide habitats that some species can exploit. Flying-foxes (Pteropus spp.) are becoming increasingly urbanized; which is thought to be a result of increased availability and temporal stability of urban food resources, diminished natural food resources, or both. Previous research has shown that urban-roosting grey-headed flying-foxes (Pteropus poliocephalus) preferentially forage in human-modified landscapes. However, which land-use areas and food plants support its presence in urban areas is unknown. We tracked nine P. poliocephalus roosting in Adelaide, South Australia, between December 2019 and May 2020, using global positioning systems (GPS), to investigate how individuals used the urban landscape mosaic for feeding. The most frequently visited land-use category was “residential” (40% of fixes) followed by “road-side,” “reserves” and “primary production” (13–14% each). However, “reserves” were visited four times more frequently than expected from their areal availability, followed by the “residential” and “road-side” categories that were visited approximately twice more than expected each; in contrast, the “primary production” category was visited approximately five times less than expected. These results suggest that while residential areas provide most foraging resources supporting Adelaide’s flying-fox population, reserves contain foraging resources that are particularly attractive to P. poliocephalus. Primary production land was relatively less utilized, presumably because it contains few food resources. Throughout, flying-foxes visited an eclectic mixture of diet plants (49 unique species), with a majority of feeding fixes (63%) to locally indigenous Australian native species; however, in residential areas 53% of feeding visits were to non-locally indigenous species, vs only 13% in reserves. Flowering and fruiting phenology records of the food plants visited further indicated that non-locally indigenous species increase the temporal availability of foraging resources for P. poliocephalus in urban Adelaide. Our findings demonstrate the importance of residential areas for urban-roosting P. poliocephalus, and suggest that the anthropogenic mixture of food resources available in the urban landscape mosaic supports the species’ year-round presence in urban areas. Our results further highlight the importance of conserving natural habitats within the urban landscape mosaic, and stress the need for accounting for wildlife responses to urban greening initiatives

A note on the effect of concerts on the behaviour of Domestic dogs Canis lupus familiaris at Taronga Zoo, Sydney

Loud or aversive noise is a key factor that may stress animals in zoological institutions. Many zoos host concerts in their grounds, and this practice is likely to expose resident animals to loud noises. Few studies have explored the effect of concerts and events on animals in zoological institutions. Here, the behaviour of two Domestic dogs Canis lupus familiaris at Taronga Zoo, Sydney, Australia, was compared between evenings with and without concerts. Behaviours such as whining, shaking, panting and destructive behaviour, thought to reflect fear or anxiety, occurred at low levels. Hiding can also be linked to fear and anxiety but is less easy to identify; for example, time spent in kennels could be considered hiding or resting. To examine this, the proportion of time the dogs spent inside their kennels was compared between evenings with concerts and those without. No difference was found between the two conditions. This indicates that dogs were probably resting rather than ‘hiding’ inside their kennels; as this behaviour made up similar proportions of evenings with and without concerts. No behaviours that may be linked to anxiety caused by concerts were identified. More comprehensive research will be carried out to explore the effect on resident animals of concerts and events held at zoological institutions

Fast food in the city? : nomadic flying-foxes commute less and hang around for longer in urban areas

Urbanization creates novel ecological spaces where some species thrive. Geographical urbanization promotes human–wildlife conflict; however, we know relatively little about the drivers of biological urbanization, which poses impediments for sound wildlife management and conservation action. Flying-foxes are extremely mobile and move nomadically in response to flowering resources, but are now increasingly found in urban areas, for reasons that are poorly understood. To investigate the mechanisms behind flying-fox urbanization, we examined the movement of 99 satellite tracked grey-headed flying-foxes (Pteropus poliocephalus) over 1 year in urban versus non-urban environments. We found that tracked individuals preferentially visited major-urban roosts, exhibited higher fidelity to major-urban roosts, and foraged over shorter distances when roosting in major-urban areas. In contrast to other colonial species, there were no density-dependent effects of colony size on foraging distance, suggesting that at a landscape scale, flying-foxes distribute themselves across roosts in an ideal-free manner, minimizing competition over urban and non-urban foraging resources. Yet, males consistently foraged over shorter distances than females, suggesting that at a local scale foraging distances reflect competitive inequalities between individuals. Overall, our study supports the hypothesis that flying-fox urbanization is driven by increased spatiotemporal availability of food resources in urban areas; however, unlike in other species, it is likely a consequence of increased urban visitation by nomadic individuals rather than a subset of the population becoming “urban residents” per se. We discuss the implications of the movement behavior we report for the conservation and management of highly mobile species

[In Press] Synchronous abortion events in the grey-headed flying-fox (Pteropus poliocephalus)

Context: The grey-headed flying-fox (Pteropus poliocephalus) is a vulnerable species endemic to eastern and south-eastern Australia. Environmental stressors are important contributors to physiological stress, leading to synchronous abortions. Aims: We investigate the possibilities of weather conditions and anthropogenic disturbances contributing to synchronous abortion events in a grey-headed flying-fox (Pteropus poliocephalus) roost. Methods: We recorded observations of two synchronous abortion events in a flying-fox roost in Tamworth, New South Wales (NSW), Australia, during October 2017 and August 2019. Key results: Roost searches found ∼200 (October 2017) and 41 (August 2019) foetuses, equating to ∼0.5% and >0.1% of adults present at the time, respectively. Neither event was associated with significantly colder than average temperatures nor hot extremes (>42°C). Synchronous abortions cannot be easily attributed to unusually cold or hot site conditions. However, the surrounding region suffered from rainfall deficiencies, known to cause failure of flowering in diet plants, in the 6 months preceding both abortion events. Notably, no rainfall deficiency occurred in 6 months preceding August 2015 when colony size was also large, and no synchronous abortions occurred. Conclusions: Natural background rates of abortions are unlikely to explain the abortion events. The 2017 abortion event coincided with intense harassment of flying-foxes using noise agents; thus, it is possible that physiological stress was a contributor. The 2019 abortion event was associated with harassment of lesser intensity but coincided with a severe food shortage throughout surrounding regions. Implications: While it is not possible to attribute the synchronous abortion events conclusively to a single factor, the results suggest that the combination of chronic physiological stress from food shortage and acute stress from anthropogenic disturbance may have precipitated both synchronous abortion events

Using weather radar to monitor the number, timing and directions of flying-foxes emerging from their roosts

Knowledge of species’ population trends is crucial when planning for conservation and management; however, this information can be difficult to obtain for extremely mobile species such as flying-foxes (Pteropusspp.; Chiroptera, Pteropodidae). In mainland Australia, flying-foxes are of particular management concern due their involvement in human-wildlife conflict, and their role as vectors of zoonotic diseases; and two species, the grey-headed flying-fox (Pteropus poliocephalus) and the spectacled flying-fox (P. conspicillatus), are currently threatened with extinction. Here we demonstrate that archival weather radar data over a period of ten years can be used to monitor a large colony of grey-headed flying-foxes near Melbourne. We show that radar estimates of colony size closely match those derived from traditional counting methods. Moreover, we show that radar data can be used to determine the timing and departure direction of flying-foxes emerging from the roost. Finally, we show that radar observations of flying-foxes can be used to identify signals of important ecological events, such as mass flowering and extreme heat events, and can inform human activities, e.g. the safe operation of airports and windfarms. As such, radar represents an extremely promising tool for the conservation and management of vulnerable flying-fox populations and for managing human interactions with these ecologically-important mammals

Climate Change and the Impacts of Extreme Events on Australia’s Wet Tropics Biodiversity: Final Report

The project investigated the exposure and sensitivity of Wet Tropics plants and animals to extreme climatic events, such as heat waves, fires, flooding rain and cyclones. This information will be used to assess and map the vulnerability of species in the Wet Tropics Bioregion and the impact of current and future climatic events on biodiversity in the region. The information gathered in the Wet Tropics can potentially be applied to other regions in Australia and elsewhere to predict and mitigate the impacts of extreme climatic events on biodiversity

Climate change and the impacts of extreme events on Australia's Wet Tropics biodiversity

[Extract] This project proposes to provide information and tools to enable scientists and management agencies to predict and limit the impacts of extreme climatic events on Australia's biodiversity. It aims to determine the exposure, sensitivity and vulnerability of Wet Tropics biodiversity to climatic extremes, and assess contemporary and future impacts. Landscape-scale exposure will be mapped by determining relationships between broad-scale macro climate and direct measurements of organism exposure in different environments. Microhabitat-scale exposure will be determined by combining the microhabitat preferences of Wet Tropics biota with the thermal characteristics of their known preferred habitat. Landscape-scale and microhabitat-scale exposure will be combined to map accurately temperatures experienced by organisms in-situ. Sensitivity of Wet Tropics biota to temperature extremes will be determined by integrating information on their thermal tolerance limits, their resilience, and their capacity to adapt. Thermal tolerance limits have already been quantified by the James Cook University researchers for a range of representative taxa. Using validated methodology, data on thermal physiology of an additional 25 key taxa will be collected in-situ. Resilience will be quantified from known traits that affect a species’ ability to survive and recover from an environmental insult. The capacity to adapt will be estimated by comparing the thermal characteristics of a species’ most favourable microhabitat with that of its other viable habitats. The three types of information will then be combined to obtain highly accurate estimates for the sensitivities of a range of representative Wet Tropics species. The project will explicitly incorporate the correlative and, where possible, mechanistic links between exposure and sensitivity to model spatiotemporal variation in current and future vulnerability to extreme temperature events. This will enable the mapping of impacts of anthropogenic changes in the regimes of temperature extremes on the distribution, abundance and extinction risk of species, something that has not been attempted before in any region. The project will initially concentrate on the regimes of temperature extremes; however, analytical approaches will then also be applied to the regimes of other extreme climatic events, particularly droughts and wildfires as they are strongly linked to extreme heat events. The ultimate aim is to develop a generalised framework for assessing the vulnerability of any natural system to any extreme climatic event. This will be critical for informing proactive conservation strategies that minimise biotic vulnerability to such events in the face of climate change. Project outputs at a glance Accurate high resolution maps of the exposure to temperature extremes as experienced by organisms in-situ. Accurate estimates of the sensitivities of organisms to temperature extremes. Identification of the areas where biodiversity is currently most vulnerable to temperature extremes ('thermal hotspots'). Identification of the areas where biodiversity is least vulnerable to temperatures extremes in the future ('thermal refugia'). A list of biodiversity values particularly at risk from extreme events. A generalised analytical toolkit for assessing vulnerability to extreme climatic events in Australia and elsewhere. Specific objectives and intended outputs of this Project are detailed in the NERP TE Hub Multi-Year Research Plan