Australian flying fox die-offs
In the last two decades tens of thousands of Australian flying foxes have died during extreme heat events. Flying fox die-offs feature arguably among the most dramatic mass mortality events witnessed in nature, but they can be indicators of heat stress in more cryptic fauna where impacts are more difficult to assess. The die-offs are important additional threats to Australian flying-foxes and the ecosystem services they provide, and highlight the complex implications of climate change for behaviour, demography, and species survival.
Impacts on species
Two Australian flying fox species have reportedly been affected by extreme heat events: the grey-headed flying fox (Pteropus poliocephalus) and the black flying fox (P. alecto). Where mixed-species colonies are affected the black flying fox suffers substantially higher mortality than the grey-headed flying fox. However, summer temperatures are more extreme within the range of the grey-headed flying fox than within the range of the black flying-fox, and therefore the actual total number of casualties is much higher among grey-headed flying foxes than black flying foxes.
Impacts on demography
Mortality is especially high among dependent young and lactating females, but any demographic category can be affected.
Impacts on behaviour
- shade-seeking and clustering
- panting, and
Beyond this individuals tend to be found near the base of trees where they form piles of lethargic and dead bats.
List of known Australian flying fox die-offs
|Event||Date||State||Area||Number of camps affected||Minimum mortality estimate||Maximum mortality estimate||Species affected||Source||comments|
|1||February 1790||NSW||Sydney||grey-headed flying fox||Tench 1793|
|2||December 1905||NSW||Helidon||grey-headed flying fox||Ratcliffe, 1932|
|3||January 1913||NSW||Mallanganee||grey-headed flying fox||Ratcliffe, 1932|
- Welbergen, J.; Klose, S.; Markus, N.; Eby, P. (2008). "Climate change and the effects of temperature extremes on Australian flying-foxes". Proceedings. Biological sciences / the Royal Society 275 (1633): 419–425. doi:10.1098/rspb.2007.1385. PMC 2596826. PMID 18048286. //www.ncbi.nlm.nih.gov/pmc/articles/PMC2596826/.
- Tench, Watkin (1793). Complete account of the settlement at Port Jackson; Including An Accurate Description of the Situation of the Colony; of the Natives; and Of Its Natural Productions. London: G. Nicol and J. Sewell.
- Ratcliffe, F (1932). "Notes on the fruit bats (Pteropus spp.) of Australia". Journal of Animal Ecology 1: 32–57. http://www.jstor.org/stable/993.