Thermal image of a juvenile grey-headed flying fox during an extreme temperature event

In the last two decades tens of thousands of Australian

flying fox ''Pteropus'' (suborder Yinpterochiroptera) is a genus of megabats which are among the largest bats in the world. They are commonly known as fruit bats or flying foxes, among other colloquial names. They live in South Asia, Southeast Asia, Aust ...

es have died during extreme heat events. Flying fox die-offs feature arguably among the most dramatic

mass mortality event A mass mortality event (MME) is a incident that kills a vast number of individuals of a single species in a short period of time. The event may put a species at risk of extinction or upset an ecosystem. This is distinct from the mass die-off ass ...

s witnessed in nature, but they can be indicators of

heat stress Hyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme ...

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 Ecosystem services are the many and varied benefits to humans provided by the natural environment and healthy ecosystems. Such ecosystems include, for example, agroecosystems, forest ecosystem, grassland ecosystems, and aquatic ecosystems. ...

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 The grey-headed flying fox (''Pteropus poliocephalus'') is a megabat native to Australia. The species shares mainland Australia with three other members of the genus ''Pteropus'': the little red '' P. scapulatus'', spectacled '' P. conspicill ...

(''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. On occasion, the federally endangered

spectacled flying fox The spectacled flying fox (''Pteropus conspicillatus''), also known as the spectacled fruit bat, is a megabat that lives in Australia's north-eastern regions of Queensland. It is also found in New Guinea and on the offshore islands including Wood ...

(''Pteropus conspicillatus'') may be affected as well, further threatening the species in Australia.

Impacts on demography

Mortality is especially high among dependent young and lactating females, but any demographic category can be affected.

Impacts on behaviour

Observations in flying fox colonies during extreme heat events have revealed that flying foxes go through a predictable sequence of

thermoregulatory Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature ...

behaviours with rising temperatures: * wing-fanning * shade-seeking and clustering * panting * salivation Beyond this, individuals tend to be found near the bases of trees where they form piles of lethargic and dead bats.

List of recorded Australian flying fox die-offs

References

External links

*ARKive �
images and movies of the grey-headed flying-fox ''(Pteropus poliocephalus)''
{{Pteropodidae, P. Heat waves in Australia Pteropus 2000s in Australia 2010s in Australia Environmental issues in Australia