Flying-fox conservation & management
Flying-foxes (Pteropus spp.) are charismatic bats found across the Old World and Australia. They are among the most mobile mammals on earth by most measures, and their extreme mobility makes them key long-distance pollen and seed dispersers in Australia’s fragmented forest ecosystems. However, flying-foxes are subject to a range of anthropogenic threats and information on the species' status and trends is limited, hampering sound conservation and management.
We have recently obtained funding under Australia's Regional Bushfire Recovery for Multiregional Species and Strategic Projects Program for three projects that aim to develop methods to improve the conservation management of the Grey-headed Flying-fox, a species that was heavily affected by Australia's recent megafires.
Project 1 - Capitalising on new methodologies (radar and drones) to monitor flying-foxes at nationally important camps
Sound management of the Grey-headed Flying-fox is reliant on accurate and precise monitoring information of this highly mobile and widely distributed species (DAWE, 2021). Traditional counting methods have limited accuracy and precision, and are subject to errors that are not well-defined (McCarthy et al., in press; Westcott et al., 2012). While data collected quarterly under the National Flying-Fox Monitoring Program (NFFMP; Westcott et al., 2015) do not provide accurate estimates of the absolute national population size of the Grey-headed Flying-fox, they are meaningful indicators of long-term population trends. Nevertheless, limited precision, combined with the low quarterly survey rates, means that population trends can only be established with significance after (many) years of monitoring (e.g., Westcott et al., 2015). Our team has recently demonstrated that drone-based thermal remote sensing provides a highly accurate and precise new tool for monitoring the abundance of flying-foxes in a roost (McCarthy et al., 2021; Fig. 1A). In addition, our team has demonstrated that weather radar data provide reliable information on the abundance of flying-foxes in a roost, both retrospectively and in real-time (Meade et al., 2019). In this project, we capitalize on these two novel flying-fox monitoring methodologies to improve the accuracy, precision and temporal resolution of the NFFMP, thus greatly enhancing the capacity for the NFFMP to detect significant population trends over shorter timeframes, allowing management to respond more quickly and proactively to threats.
AIM: The aim of this project is to develop a drone-calibrated landscape-scale network of 10 "nationally important" Grey-headed Flying-fox camps to be monitored using weather radar data at a daily basis (retrospectively and in real-time).
OUTCOMES: This project will result in a network of radar-monitored camps, where reliable information on flying-fox abundance will be available for a period of up to 30 years. This represents an important advance on the knowledge of previous flying-fox population dynamics at a landscape scale. The calibrated, radar-monitored network of camps, in addition to being valuable for the monitoring of grey-headed flying-foxes in its own right, will also provide an important proof-of-concept to help us to assess the utility of deploying the approach at larger scales for improving the monitoring under the NFFMP as a whole.
TEAM: Assoc Prof Justin Welbergen (Western Sydney University); Dr Jessica Meade (Western Sydney University); Dr John Martin (Taronga Conservation Society Australia).
PARTNERS: Dr David Westcott (CSIRO, NFFMP); Adam McKeown (CSIRO, NFFMP); Jeff McKee (Avisure); with state-level representatives: NSW: Matthew Mo; Qld: Lindsey Delzoppo; Vic: Lachlan Clarke; ACT: Renee Brawata; SA: Jason Van Weenen.
Project 2: Developing remotely sensed landscape-scale nectar availability maps to identify spatially explicit targets for flying-fox habitat conservation and restoration
Grey-headed flying-foxes provide essential ecosystem services through pollination, but are increasingly threatened by habitat loss, as exemplified by Australia’s 2019/2020 megafires (Boer et al., 2020; Nolan et al., 2020). Quantifying the resources available in space and time via nectar availability mapping would provide a powerful tool for identifying spatially explicit targets for habitat conservation and rehabilitation, to benefit the grey-headed flying-fox as well as other nectarivores, along with the trees they service. Important recent advances in drone technologies (e.g., Weiss et al., 2020) and the spatiotemporal resolution and availability of satellite imagery (e.g., Drusch et al., 2012) now provide the opportunity to develop high-resolution nectar availability maps at the landscape scale. With the proposed project we intend to capitalize on these recent technological advances to map the eucalypt flowering abundance across eastern Australia. Importantly, we will use our existing Grey-headed Flying-fox satellite telemetry dataset (Welbergen et al., 2020) and the National Flying-Fox Monitoring Program (NFFMP) data (Westcott et al., 2015) to validate externally our remote-sensed nectar availability maps, something that has not been achieved previously.
AIM: The aim of this project is to combine drone- and satellite-based multispectral remote sensing to generate nectar resource availability maps identifying important habitat areas for grey-headed flying-foxes from local to landscape scales across eastern Australia.
OUTCOMES: The project will provide accurate estimates of the amount of nectar resources lost due to Australia’s 2019-20 megafires, and provide spatially explicit targets for conservation and restoration. The benefits of this project extend beyond that of the Grey-headed Flying-fox to other threatened nectarivores as well as economic assets that rely on Australia’s dwindling nectar supplies.
TEAM: Team: A/Prof Justin Welbergen (Western Sydney University; WSU); Dr Jessica Meade (WSU); A/Prof Mathias Boer (WSU); Prof James Cook (WSU); Dr John Martin (Taronga Conservation Society Australia; TCSA)
PARTNERS: Dr David Westcott (CSIRO, NFFMP); Adam McKeown (CSIRO, NFFMP); with state-level representatives: NSW: Matthew Mo; Qld: Lindsey Delzoppo; Vic: Lachlan Clarke; ACT: Renee Brawata; SA: Jason van Weenen.
Project 3 - Testing the efficacy of roost microclimate manipulation for mitigating heat stress in flying-foxes
Heatwaves are now hotter, longer and more frequent than 50 years ago, and this trend is set to continue under anthropogenic climate change (Cowan et al., 2014). Extreme heat events are well known to result in substantial die-offs in flying-fox populations (Mo et al., 2021; Ratnayake et al., 2019; Welbergen et al., 2008), with many tens of thousands of flying-foxes having succumbed due to heat stress across SA, Vic, NSW, & Qld during the past decade alone. A now-common intervention aimed to help mitigate the worst of the impacts of extreme heat events on flying-foxes involves ‘spraying’ (or ‘misting’) of the roost environment. This practice is known to reduce ambient temperatures via evaporative cooling; however, it can also increase relative humidity (decrease water vapour pressure), and under extreme conditions this is known to reduce the effectiveness of animal thermoregulatory mechanisms (e.g., Cooper and Withers, 2008; Kurta, 2014; Lasiewski et al., 1966; Procter and Studier, 1970; Webb et al., 1995), and so risks exacerbating heat stress. The combined effects of spraying on roost temperature and humidity, and hence flying-fox heat stress, have not been formally assessed, impeding the development of effective heat stress interventions (Mo and Roache, 2020). To address this knowledge gap, we have developed a project in which we: i) map temperature and humidity across roosts subject to spraying, to quantify explicitly the effects of spraying on a roost’s microclimatic conditions; and ii) collect behavioural and physiological data on thermoregulatory behaviours in response to the (altered) microclimatic conditions, to construct a temperature-humidity index (‘heat stress index’) for flying-foxes. In combination, these approaches enable us to infer and validate the efficacy of spraying on FF heat stress and establish much-needed temperature-humidity thresholds for intervention.
AIM: The aim of this project is to validate the efficacy of spraying on flying-fox heat stress and establish much-needed temperature-humidity thresholds for intervention.
TEAM: A/Prof Justin Welbergen (WSU); Dr Christopher Turbill (WSU); Dr Jessica Meade (WSU); Dr John Martin (TCSA)
PARTNERS: Matthew Mo (NSW DPE)
Research team members
The projects are conducted by members and affiliates of the Lab of Animal Ecology at the Hawkesbury Institute for the Environment in collaboration with the Taronga Conservation Society:
- A/Prof Justin Welbergen - Hawkesbury Institute for the Environment (Western Sydney University)
- Dr Jessica Meade - Hawkesbury Institute for the Environment (Western Sydney University)
- Prof Matthias Boer - Hawkesbury Institute for the Environment (Western Sydney University)
- Dr Christopher Turbill - Hawkesbury Institute for the Environment (Western Sydney University)
- Dr John Martin - Taronga Conservation Society AustraliaOur Research Program
- MCCARTHY, E. D., MARTIN, J. M., BOER, M. M. & WELBERGEN (in press). Ground-based counting methods underestimate true numbers of a threatened colonial mammal: an evaluation using drone-based thermal surveys as a reference. Wildlife Research
- MO, M., MINEHAN, M., HACK, E., PLACE, V. & WELBERGEN J. A. (in press) A report of direct mortality in grey-headed flying-foxes (Pteropus poliocephalus) from the 2019-20 Australian megafires. Australian Mammalogy
- MO, M., MEADE, J., PRICE J. C., MAISEY, J. C. & WELBERGEN J. A. (2022). Synchronous abortion events in the grey-headed flying-fox (Pteropus poliocephalus). Pacific Conservation Biology, doi: 10.1071/PC21060
- YABSLEY, S. H., MEADE, J., MARTIN, J. M., & WELBERGEN, J. A. (2021). Human-modified landscapes provide key foraging areas for a threatened flying mammal: The grey-headed flying-fox. Plos one, 16(11), e0259395.
- MEADE, J., MARTIN, J. M., & WELBERGEN, J. A. (2021). Fast food in the city? Nomadic flying-foxes commute less and hang around for longer in urban areas. Behavioral Ecology.
- MCCARTHY, E. D., MARTIN, J. M., BOER, M. M. & WELBERGEN (2021). Drone-based thermal remote sensing provides an effective new tool for monitoring the abundance of roosting fruit bats. Remote Sensing in Ecology and Conservation.
- RATNAYAKE, H. U., WELBERGEN J.A., VAN DER REE, R & KEARNEY, M. R. (2021) Variation in fur properties may explain differences in heat-related mortality among Australian flying-foxes. Australian Journal of Zoology, 68:285-295MO, M., ROACHE, M., DAVIES, J., HOPPER, J., PITTY, H., FOSTER, N., ... & WELBERGEN, J. A. (2021). Estimating flying-fox mortality associated with abandonments of pups and extreme heat events during the austral summer of 2019–20. Pacific Conservation Biology
- TIMMISS, L. A., MARTIN, J. M., MURRAY, N. J., WELBERGEN, J. A., WESTCOTT, D., MCKEOWN, A., & KINGSFORD, R. T. (2021). Threatened but not conserved: flying-fox roosting and foraging habitat in Australia. Australian Journal of Zoology, 68:226–233
- WELBERGEN, J. A., MEADE, J., FIELD, H., EDSON, D., McMICHAEL, L., SHOO, L. P., PRASZCZALEK, J., SMITH, C., MARTIN, J. (2020) Extreme mobility of the world's largest flying mammals creates key challenges for management and conservation. BMC Biology, 18:101
- LENTINI, P. & WELBERGEN, J. A. (2019). Managing tensions around urban flying‐fox roosts. Austral Ecology, 44 (2): 380-385. DOI: 10.1111/aec.12738 (HOT TOPIC)
- RATNAYAKE, H. U., KEARNEY, M, R., GOVEKAR, P., KAROLY, D. & WELBERGEN, J. A. (2019) Forecasting wildlife die-offs from extreme heat events. Animal Conservation, 22(4): 386-395. DOI: 10.1111/acv.12476
- MEADE, J., VAN DER REE, R., STEPANIAN, P. M., WESTCOTT, D. A. & WELBERGEN, J. A., 2019. Using weather radar to monitor the number, timing and directions of flying-foxes emerging from their roosts. Scientific Reports, 9(1):10222.
- WELBERGEN, J. A., KLOSE, S. M., MARKUS, N. & EBY, P. (2008) Climate change and the effects of temperature extremes on Australian flying-foxes. Proceedings of the Royal Society of London, Series B 275, 419-425