In the last two decades tens of thousands of Australian flying foxes have died during extreme heat events. [1] 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.
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. [1] 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 (Pteropus conspicillatus) may be affected as well, further threatening the species in Australia.
Mortality is especially high among dependent young and lactating females, but any demographic category can be affected. [1]
Observations in flying fox colonies during extreme heat events have revealed that flying foxes go through a predictable sequence of thermoregulatory behaviours with rising temperatures: [1]
Beyond this, individuals tend to be found near the bases of trees where they form piles of lethargic and dead bats.
Event | Date | State | Area | Number of camps affected | Minimum mortality estimate | Maximum mortality estimate | Species affected | Source |
---|---|---|---|---|---|---|---|---|
1 | February 1791 | NSW | Sydney | grey-headed flying fox | Tench 1793 [1] [2] | |||
2 | December 1905 | NSW | Helidon | grey-headed flying fox | Ratcliffe, 1932 [1] [3] | |||
3 | January 1913 | NSW | Mallanganee | grey-headed flying fox | Ratcliffe, 1932 [1] [3] | |||
4 | January 1994 | Qld | Townsville and Ipswich | 2 | 1000 | grey-headed flying fox, black flying fox | Welbergen et al., 2008 [4] | |
5 | December 1994 | NSW | Cabramatta and Gordon | 2 | 6000 | 6000 | grey-headed flying fox | Welbergen et al., 2008 [4] |
6 | late 1900s | NT | 1 | 29 | 29 | grey-headed flying fox | Tidemann & Nelson 2011 [4] | |
7 | January 2000 | Qld | Ipswich | 500 | 500 | grey-headed flying fox, black flying fox | Welbergen et al., 2008 [4] | |
8 | 12 January 2002 | NSW | Murwillumbah | 9 | 3679 | grey-headed flying fox, black flying fox | Welbergen, Klose et al., 2008 [4] | |
9 | January 2003 | NSW | Cabramatta and Gordon | 2 | 5000 | 5000 | grey-headed flying fox | Welbergen et al., 2008 [4] |
10 | January 2004 | NSW | Bellingen | 1 | 3000 | 8000 | grey-headed flying fox | Welbergen et al., 2008 [4] |
11 | December 2004 | NSW | Coff's Harbour | 2 | 1000 | 5000 | grey-headed flying fox | Welbergen et al., 2008 [4] |
12 | December 2005 | Qld, NSW, Vic | 3 | 5613 | 8900 | grey-headed flying fox, black flying fox | Welbergen et al., 2008 [4] | |
13 | January 2006 | NSW, Vic | 6 | 4273 | 4843 | grey-headed flying fox | Welbergen et al., 2008 [4] | |
14 | December 2006 to January 2007 | Vic | Melbourne | 2 | 207 | 207 | grey-headed flying fox | Welbergen et al., 2008 [4] |
15 | January 2014 | Qld | >25 | 100000 | grey-headed flying fox, black flying fox | Murphy 2014, Saunders 2014 [4] | ||
16 | November 2014 | NSW | Casino and Richmond Valley | 2 | 7000 | 7000 | grey-headed flying fox, black flying fox | Godfrey 2014 [4] |
17 | November 2018 | Qld | 33000 | 40000 | spectacled flying fox, black flying fox | [5] | ||
18 | December 2019 | Vic | Melbourne | 4500 | grey-headed flying fox | [6] [7] |
Megabats constitute the family Pteropodidae of the order Chiroptera (bats). They are also called fruit bats, Old World fruit bats, or—especially the genera Acerodon and Pteropus—flying foxes. They are the only member of the superfamily Pteropodoidea, which is one of two superfamilies in the suborder Yinpterochiroptera. Internal divisions of Pteropodidae have varied since subfamilies were first proposed in 1917. From three subfamilies in the 1917 classification, six are now recognized, along with various tribes. As of 2018, 197 species of megabat had been described.
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The giant golden-crowned flying fox, also known as the golden-capped fruit bat, is a species of megabat endemic to the Philippines. Since its description in 1831, three subspecies of the giant golden-crowned flying fox have been recognized, one of which is extinct. The extinct subspecies was formerly recognized as a full species, the Panay golden-crowned flying fox. Formerly, this species was placed in the genus Pteropus; while it is no longer within the genus, it has many physical similarities to Pteropus megabats. It is one of the largest bat species in the world, weighing up to 1.4 kg (3.1 lb)—only the Indian and great flying fox can weigh more. It has the longest documented forearm length of any bat species at 21 cm (8.3 in).
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Pteropus 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, Australia, East Africa, and some oceanic islands in the Indian and Pacific Oceans. There are at least 60 extant species in the genus.
The little red flying-fox is a megachiropteran bat native to northern and eastern Australia. The species weighs about half a kilogram, one US pound, and is the smallest species of Pteropus in mainland Australia. P. scapulatus occurs at the coast and further inland, camping and flying to the tropical to temperate regions that provide them with an annual source of nectar. They exhibit an unusual method of obtaining drinking water during dry periods, skimming a stream's surface to gather it onto their fur while they are in flight.
The grey-headed flying fox 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. conspicillatus, and the black P. alecto. The grey-headed flying fox is the largest bat in Australia.
The spectacled flying fox, 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 Woodlark Island, Alcester Island, Kiriwina, and Halmahera.
The black flying fox or black fruit bat is a bat in the family Pteropodidae. It is among the largest bats in the world, but is considerably smaller than the largest species in its genus, Pteropus. The black flying fox is native to Australia, Papua New Guinea, and Indonesia. It is not a threatened species.
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The gray flying fox is a species of flying fox in the family Pteropodidae. It is not to be confused with the grey flying fox. It is found in Indonesia, but not in the Philippines, despite occasional reference to such. Very little is known about this species. The gray flying fox has small size and neutral coloration with a brownish head and an orange abdomen. It probably roosts individually or in small groups. It was listed on appendix II of CITES, and is classified as "Data Deficient" by the IUCN. This species has been decimated by hunting for bushmeat in Indonesia. The hunters use fishing hooks, ropes, and other supplies to hunt the bats. The ropes and hooks are placed along their flight paths, tearing and ensnaring the bats' wings when are flying. In the course of a hunting season, entire colonies can be killed.
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The great flying fox, also known as the greater flying fox or Bismarck flying fox, is a species of megabat in the genus Pteropus, found throughout lowland areas of New Guinea and in the Bismarck Archipelago. Conflicting evidence suggests that its closest relative is either the spectacled flying fox or, jointly, the Pelew and insular flying foxes. Two subspecies are recognized. At up to 1.6 kg (3.5 lb) in weight, it is among the heaviest bats in the world and the largest bat in Melanesia. It is a gregarious animal which roosts with hundreds or thousands of individuals. In part due to its wide variation in color, it has many taxonomic synonyms, including Pteropus degener, Pteropus papuanus, and Pteropus sepikensis. It may forage during the day or night in search of fruit, including figs or fruits from the family Sapotaceae. It is considered a least-concern species by the IUCN, though its numbers have been negatively impacted by what appeared to be a disease, as well as by hunting for bushmeat that occurs across its range.
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