Австралияның улы бақалары: Сирек кездесетін екі түр

Name for two species of amphibian

Corroboree frogs (/k//ə/'/ɹ//ɒ//b//ə//ɹ//i/ kuh ROB uh ree) comprise two species of frog native to the Southern Tablelands of Australia. Both species are small, poisonous ground dwelling frogs. The two species are the southern corroboree frog (Pseudophryne corroboree) and the northern corroboree frog (Pseudophryne pengilleyi). They are unique among frogs in that they produce their own poison rather than obtain it from their food source as is the case in every other poisonous frog species.

The northern form of the corroboree frog deviates slightly in having narrow yellow to greenish stripes and is slightly smaller.

The typical diet of a mature southern corroboree frog includes beetles, mites, ants and insect larvae. However, as tadpoles they also tend to eat algae and other small pieces of organic material found in their pools.

Corroboree frogs are the first vertebrates discovered that are able to produce their own poisonous alkaloid, as opposed to obtaining it via diet as many other frogs do. The alkaloid is secreted from the skin as a defence against predation, and potentially against skin infections by microbes. It has been described as potentially lethal to mammals if ingested. The unique alkaloid produced has been named pseudo phrynamine.

Corroboree frogs are quite unusual in their nature. Not only do they not start breeding until four years of age, they also hibernate during winter under whatever shelter they can find. This may be snow gum trees, or bits of bark or fallen leaves. Males stay with the egg nests and may breed with many females over the course of one season.

The southern corroboree frog was considered relatively numerous within its very small distribution in the 1970s, as of June 2004 it had an estimated adult population of 64, but suffered declines of up to 80% over the 10 years up to 1989, at which time it was found only within a fragmented region of less than within Kosciuszko National Park. It has been listed as critically endangered since at least 2004 and is considered to be one of Australia's most endangered species. There are fewer than 30 individuals left in the wild as of lc=yes. The northern corroboree frog has not suffered as badly as the southern. It is more widely distributed across about of the Brindabella and Fiery Ranges in Namadgi National Park in the ACT, and Kosciuszko National Park and Buccleuch State Forest in NSW. In 2004 it was downgraded from an IUCN assessment of critically endangered to endangered, though in 2022 this decision was reverted .

The main threats to the survival of the frogs are thought to be infection with the chytrid fungus and bushfires. Severe bushfires in the Victorian and NSW high country in January 2003 destroyed much of the frogs' remaining habitat, especially the breeding sites and the leaf litter that insulates overwintering adults. The fire affected almost all southern corroboree frog habitat, although later surveys showed that the fire resulted in a lower than expected decline in population.} The 2019–2020 bushfires in Australia destroyed a significant portion of Kosciusko National Park, and killed two thirds of the southern corroboree frogs contained in specially designed disease free enclosures built by conservationists. Other threats to the southern species include residential and commercial development (including ski resorts); climate change (causing drought and fires); and pollution. Other causes such as habitat destruction from recreational 4WD use; feral animals; degradation of the frogs' habitat; and increased UV radiation flowing from ozone layer depletion. The drought affects these frogs by drying out their breeding sites so that the breeding cycle, which is triggered by seasonal changes and may require moistening of the bogs in autumn and spring to bring on specific developmental events, is delayed. This may mean that tadpoles have not metamorphosed by late summer when their bogs dry out, and so perish.

The Amphibian Research Centre had already begun a rescue programme under which eggs were collected and raised to late tadpole stage before return as close as possible to their collection site. Research is now under way into captive breeding and on which life cycle stage – eggs, tadpoles or adults – promises the best chance of survival following return to the wild. The national parks authorities in the ACT, NSW and Victoria have developed conservation programmes, including a captive husbandry programme at Tidbinbilla, ACT; Taronga Zoo in Sydney; and at Healesville Sanctuary, by Zoos Victoria. Conservationists have stepped up efforts to increase the population of the southern corroboree frog since the 2019–20 bushfires. In March 2022, 100 frogs were released into the park as part of a joint breeding program between Taronga Zoo, Zoos Victoria, the NSW National Parks and Wildlife Service and the NSW Government's "Saving our Species" program. At this time there are five enclosures for the frogs, with the newest one built to better withstand the effect of fire.