The state and trend of mammals varies considerably. In 2014, The action plan for Australian mammals 2012 (Woinarski et al. 2014) was released. It reviews the status of all known Australian mammals, and provides a benchmark from which changes in both the population and status of all Australian mammal taxa can be assessed in the future.
In June 2016, experts confirmed the extinction of the Bramble Cay melomys (Melomys rubicola) from Australia. This small rodent was considered ecologically unique in being the Great Barrier Reef’s only endemic mammal species (Gynther et al. 2016). The species was listed as endangered under Queensland and Australian legislation, and a recovery plan was developed in 2008. The melomys occurred only on Bramble Cay, a small (less than 5 hectare) island in Torres Strait. Intensive monitoring in 2014 failed to find any evidence of the species; a report by the Queensland Government determined the probable cause of the extinction to be sea level rise, and an increase in the frequency and severity of storm surge (Gynther et al. 2016).
The extinction of the Bramble Cay melomys followed that of the Christmas Island pipistrelle (Pipistrellus murrayi), a tiny insect-eating bat, in 2009. Although its decline had been monitored for 15 years, the decision to start a captive breeding program was delayed for 3 years after the program was first recommended, and no individuals could be captured (Martin et al. 2012). The last echolocation call of the species was detected in August 2009.
In northern Australia, evidence of ongoing mammal declines (major extinction of mammals occurred following European settlement of Australia; Figure BIO19) has continued to be evident in the Top End of the Northern Territory and the Kimberley region of Western Australia. Although not definitive, Cape York Peninsula has remained relatively stable, with the composition of mammal fauna in surveys from 2009 to 2012 similar to that from early descriptions (1948–80) and from surveys in 1985 (Perry et al. 2015).
In encouraging signs in arid Australia, improved data and targeted surveys have led to a better understanding of the distribution and abundance of critically endangered species (see Box BIO8), and the recommended downlisting of the conservation status of other species, such as marsupial moles (Woinarski et al. 2014).
In southern and eastern Australia, the number of species of conservation concern has increased, including what were previously common mammals. For instance, the arboreal greater glider (Petauroides volans) was once a common species but is now in steep decline (Lindenmayer et al. 2015) and has been listed as vulnerable under the EPBC Act. Some species face imminent extinction. The Leadbeater’s possum has been listed as a species needing emergency intervention under the Australian Government’s of 2015.
The action plan for Australian mammals 2012 (Woinarski et al. 2014) recommended major changes to the current list of mammals under the EPBC Act, leading to many species being listed for the first time or delisted, or having their status upgraded or downgraded. Many other species have been prioritised for assessment because of the action plan. The overall picture shows more decline than improvement. The plan recommended that:
- 39 EPBC Act–listed species (or at least 1 subspecies if the species is not listed) be elevated to one of the threatened categories or have the category that they are in elevated to a higher threat level (e.g. from vulnerable to endangered)
- 21 EPBC Act–listed species be delisted from one of the threatened categories or have the category that they are in downgraded to a lower threat level (e.g. from endangered to vulnerable)
- 8 EPBC Act–listed subspecies (where the species is not listed as threatened) be delisted from one of the threatened categories or have the category that they are in downgraded to a lower threatened level.
The action plan for Australian mammals 2012 also recommended retrospectively adding 8 extinct (species) that were previously not described or recognised as species under the EPBC Act: western long-beaked echidna (Zaglossus bruijni), desert bettong (Bettongia ogilbyi), Nullarbor dwarf bettong (Bettongia pusilla), Capricorn rabbit-rat (Conilurus capricornensis), broad-cheeked hopping mouse (Notomys robustus), long-eared mouse (Notomys macrotis), blue-grey mouse (Pseudomys glaucus) and Percy Island flying fox (Pteropus brunneus). These species add to the severity of the modern extinction event of mammals in Australia (Figure BIO19); the 30 mammal extinctions in Australia since European settlement is vastly greater than that recorded for any other country (Woinarski et al. 2015).