The Flying-Fox Radar Monitor

What is this about?

Flying-foxes (Pteropus spp.) are large, extremely mobile bats that are difficult to monitor, which poses serious impediments to the sound conservation management of these ecologically important species (Welbergen et al., 2020). 
Traditional counting methods have limited accuracy and precision, and are subject to errors that are not well-defined (McCarthy et al., in press), which means that population trends can only be established with significance after (many) years of monitoring (e.g., Westcott et al., 2012, 2015). However, our team has recently demonstrated that weather radar data provide reliable information on the abundance of flying-foxes in a camp (roost), both retrospectively and in real-time (Meade et al., 2019). In addition, we have shown that drone-based thermal remote sensing provides a highly accurate and precise new tool for monitoring the abundance of flying-foxes in a camp (McCarthy et al., 2021). 
Capitilising on these recent methodological advances, we are currently developing a drone-calibrated landscape-scale network of nationally important camps of the vulnerable grey-headed flying-fox (P. poliocephalus) in Australia, as part of our project funded under Australia's Regional Bushfire Recovery for Multiregional Species and Strategic Projects Program. We anticipate that this network will provide reliable information on how the species is distributed across its distribution, both in real-time and going back for a period of up to 20 years, thus greatly enhancing the capacity for flying-fox conservation managers to detect significant population trends over shorter timeframes and respond more quickly and proactively to threats.
Below are the preliminary outcomes of our ongoing work, showing the real-time and archival weather radar-derived estimates of the numbers of flying-foxes present in select camps. As our project progresses, additional camps will be added, and the radar-derived estimates will continually be refined by callibrating them against our observations from drone-based thermal remote sensing.​
Adelaide Botanic Gardens Yarra Bend Bairnsdale Kareela Macquarie Fields Raymond Terrace East Cessnock Grafton Maclean Gympie Woocoo Hervey Bay

Adelaide Botanic Gardens (Adelaide, South Australia)
Species present:  P. poliocephalus only. This camp was established in 2011.  

Yarra Bend (Melbourne, Victoria)
Species present: P. poliocephaluys only. The camp was established in 2003, following dispersal of flying-foxes from the Melbourne Botanical Gardens.

Kareela (Sydney, New South Wales)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

Macquarie Fields (New South Wales)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

Raymond Terrace (New South Wales)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

East Cessnock ​(New South Wales)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

Grafton ​(New South Wales)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

Maclean ​(New South Wales)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

Gympie ​(Queensland)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

Woocoo ​(Queensland)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto. At times, this camp experiences very large influxes of P. scapulatus, such as in mid-2019.

Hervey Bay ​(Queensland)
Species present: predominantly P. poliocephalus with much smaller numbers of P. alecto

Background information

​About flying-foxes
​Flying-foxes are charismatic, very large species of bat that forage by night and roost by day in arboreal roosts that can comprise tens of thousands of individuals. They provide important ecosystem services, including pollination of wild and cultivated crops and seed dispersal (e.g. Fujita & Tuttle 1991). However, they are exposed to threatening anthropogenic factors (Mickleburgh et al 1992), the most serious of which are XXX.
Flying-fox monitoring
​Monitoring is required XXX
About the flying-fox radar monitor
our team has recently demonstrated that weather radar data provide reliable information on the abundance of flying-foxes in a camp (roost), both retrospectively and in real-time.  The radar monitor estimates the numbers of bats emerging from their camps by XXX, using the methodology detailed in Meade et al. (2019).
Limitations of the flying-fox radar monitor
​XXX
Plans for further development and applications
XXX

Useful links


See also:

Attributions & acknowledgements

Conception: Justin Welbergen, Jessica Meade
Scripts: Jessica Meade
​Web design: Justin Welbergen

​Necessary disclaimer

Our flying-fox radar estimates are based on best-practice predictions from computer model data. Nevertheless, the predictions may under- or overestimate the true numbers of flying-foxes present. ​We cannot accept any responsibility for the loss or damage that may result from reliance on, or the use of, any information contained on this webpage.

References

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
​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, 32: 1151-1162
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: e0259395.
​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, 7: 461-474
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
​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.