The RSPCA has released a discussion paper on cat management. I'll be blogging the details of this paper over the coming weeks, with the deadline for submissions being the 27 July 2017.
Lots to talk about - so let's just get started.
From the introduction
Feral cat predation is considered to be a major contributor to the extinction of 22 Australian mammals (Woinarski et al. 2015)...
So what is "Woinarski; 22 Australian mammals"?
This paper is available here and titled "Ongoing unraveling of a continental fauna: Decline and extinction of Australian mammals since European settlement".
It is a brief, published paper of a larger document "The Action Plan for Australian Mammals 2012" which is over 1,000 pages and costs over $100, which is probably why most people quoting the "22 extinct mammals" statistic... haven't read the full paper.
However, the "Ongoing unraveling of a continental fauna" brief asserts that while in other countries animal extinctions are caused by "...habitat loss, hunting, and impacts of human development...". - that in contrast Australia;
... should have relatively few conservation concerns: its population density is extremely low (∼3 km−2 ) by global standards (∼50 km−2), most of the continent remains very sparsely settled and little modified, and the Australian nation is relatively affluent: indeed, most of the continent comprises one of the world’s few remaining large areas of largely natural environments.
At which point you should already be pretty cynical as to where this would be going. Does Australia truly boast a "natural environment"? According to the Department of Agriculture and Water Resources, not so much...
(http://www.agriculture.gov.au/abares/aclump/land-use)
Just 23% of Australia is deemed "Nature conservation/Other protected areas" leaving nearly 80% of Australia being used for other human-centric uses including grazing cattle and growing crops. And to be fair, the paper does pay lip service (on page six) to the idea that cats aren't the only introduced animal causing havoc to native environments - contradicting its own claim that Australia is mostly "natural"
Pastoralism based on introduced sheep and cattle is now the dominant land use across much of Australia, and many other introduced herbivores (notably including the rabbit, goat, donkey, camel, horse, and buffalo) collectively occur abundantly beyond the pastoral estate across the entire Australian land mass, including in many conservation reserves. Competition with, and habitat degradation caused by, introduced herbivores has also been detrimental to many Australian mammals, as demonstrated by livestock removal experiments and correlative studies that compare mammal assemblages in comparable areas with and without introduced herbivores (91–93)
But this is only a short break, before they then they get swiftly back to pointing the finger at the cat.
Although the detail of the patterning is imprecise, the available evidence indicates a broad sequential wave of mammal losses, beginning from the first settled areas in southeastern Australia (coincident with the first arrivals of some associated threats) from the 1840s, reaching central Australia in the 1890s with rapid declines there particularly over the period of 1930– 1960, and marked losses continuing from about the 1960s to the present day in much of northern Australia.... Much of this timing was coincident with the continent-wide spread of the introduced cat Felis catus and the slightly later and only marginally less extensive spread of the introduced red fox Vulpes vulpes.
And,
Our assessment of 30 Australian mammal extinctions is also appreciably greater than that recognized under Australian environmental legislation, which lists 20 Australian mammal species as extinct, a tally also reported in previous assessments of the extent of loss of Australian biodiversity (26).
and,
As noted in previous studies (27–30), the losses of Australian mammal species have been taxonomically uneven, with relatively higher rates of loss in rodent and marsupial species, and relatively less loss in bat species.
So what 22/30 native animals are we talking about? Let's look at them below.
What 22 (30) species went extinct because of cats according to Woinarski and the RSPCA?
1. Thylacine (Thylacinus cynocephalus)
So first up is an easy one - no, not cats. We can remove Thylacine as related to cats, as;
"Intensive hunting encouraged by bounties is generally blamed for its extinction, but other contributing factors may have been disease, the introduction of dogs, and human encroachment into its habitat." (ref)
It is also claimed that the species may also have caught a disease, or became a victim of predation by Tasmanian Devils.
Verdict: Extinction caused by cats? Nope. Just nope.
2. Western long-beaked echidna (Zaglossus bruijnii)
The Western Long-beaked Echidna may have been a "rare" species in Australia prior to 1788. It was last seen around 120 years ago, and has only been collected once in Australia; in the south-west Kimberley of Western Australia in 1901. It has not been collected or reported since.
Helgen et al. (2012) reported on a previously overlooked specimen collected in the Kimberley region of northwestern Australia in 1901. This specimen suggests that the distribution of the species extended into northwestern Australia where it persisted as a rare species until the early twentieth century. (ref)
The station on which this specimen was found had been "settled and grazed" by the time that the only known specimen was found. Frequent, more extensive fires became the norm after pastoralism was established and Aboriginal people moved to settlements, as "fire regimes in the western deserts changed from mostly small fires resulting in a mosaic of fire ages to one of infrequent, very large summer fires, with consequences for food availability and habitat suitability demonstrated for small desert macropods"
It is noted that large echidnas were also probably hunted for food by indigenous people. The reasons for its extinction in Australia are noted as "speculative" and "unknown" and now these echidnas are restricted to the Vogelkop Peninsula region of Papua Province, Indonesia.
Verdict: Extinction caused by cats? Unknown and speculative at best. Probably cascading environmental factors including pastoralism.
3. Pig-footed bandicoot (Chaeropus ecaudatus)
This species had a sparse distribution and was never abundant. It became extinct probably 120 years ago, in the early to mid-1900s and before many studies had been undertaken on it.
According to Indigenous Australian oral tradition this species was rare even before the arrival of Europeans on the continent and was in a serious decline even as it first came to scientific notice in the middle years of the 19th century. The cause of the extinction remains uncertain: neither... the fox and the rabbit, had yet arrived in south-west Western Australia when the pig-footed bandicoot disappeared from that area. Feral cats were already common, which may offer an explanation; it is perhaps more likely that the decline was caused by a double habitat change.
Firstly, the end of many thousands of years of Aboriginal burning which, being confined to a patchwork of small areas at any one time, had ensured both fresh new growth in the recently burnt areas and adjacent older growth for shelter and as a base for recolonisation. However, Australia's Aboriginal population had declined by around 90% during the 19th century, largely because of the introduction of European diseases, and the remaining Aborigines were often no longer permitted to carry on their traditional land-management and hunting practices.
Secondly, following on the heels of the near-extermination of the Aborigines, came the introduction of vast numbers of sheep and cattle, leading to significant changes in soil structure, plant growth, and food availability. (ref)
Sheep grazing severely degraded the habitat needed by this species to survive as it nested on the ground or in grass-lined burrows. There is also speculation that there was a disease outbreak which is "considered to provide a more satisfactory explanation" of early declines in WA than predation by feral cats.
Verdict: Extinction caused by cats? Unknown and speculative at best. Probably made extinct by an introduced disease, combined with cascading environmental factors, including pastoralism.
4. Desert bandicoot (Perameles eremiana)
The last time this species was collected was in 1943, though it is reported that "people were eating it" right up until 1960. It was believed this species was a variation of the Western Barred Bandicoot (Perameles bougainville) up until 2012, when it was given its own species classification. It was found the deserts in western and central Australia.
Favoured habitat was sandy desert with spinifex and other tussock grasses. It appears to have disappeared between about 1943 and 1960. While the cause of its decline remains uncertain, it is thought to be related to the changed burning regimes that followed the removal of Aboriginal people from the central Australian deserts. (ref)
Rabbits may have competed for food, and changes in land management saw increased summer lightening-caused fires which reduced habitat complexity and eliminated shelter and food.
Verdict: Extinction caused by cats? Unknown and speculative at best. Probably cascading environmental factors including pastoralism.
5. Yallara (Macrotis leucura)
The last specimen was collected in 1931. Its abundance is unknown. The species decline and ultimately its extinction was attributed to "several factors";
The introductions of foreign predators like the domestic cat and fox, being hunted for food by native Australians, competition with rabbits for food, changes in the fire regime and the degradation of habitat have all been blamed for the extinction of this species. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best. Probably cascading environmental factors including pastoralism.
6. Desert bettong (Bettongia anhydra)
The Desert Bettong is known from a single specimen collected in 1933 and has not been recorded alive since then. It was only recognised as a separate species from the Boodie (Bettongia lesueur) in 2013. Its range is unknown. It was probably vulnerable to fire regime changes which increased the number of summer fires, which destroyed its habitat and food sources.
Verdict: Extinction caused by cats? Very little information known about the species. Speculative at best.
7. Nullarbor dwarf bettong (Bettongia pusilla)
Nullarbor dwarf bettong is only known from subfossil records and is considered extinct at european settlement.
The Nullarbor Dwarf Bettong was described very recently (McNamara 1997)… It has never been reported alive. (ref)
It was never recorded as abundant by early trappers and other observers. While its extinction may have been the result of sheep grazing;
Pastoral leases, mainly for sheep grazing covered most of the Nullabor, where this species lived and together with rabbits, caused massive vegetation degradation. (ref)
Verdict: Extinction caused by cats? Very little information known about the species. Probably cascading environmental factors including pastoralism.
8. Desert rat-kangaroo (Caloprymnus campestris)
This species, even before European colonisation, was apparently never abundant, and may have been put under pressure by overhunting by indigenous Australians.
It was last recorded in 1935 where it was discovered by pastoralists who caught 12 specimens.
The sparse vegetation on which the species depended could easily have been severely degraded by stock. (ref)
Verdict: Caused by cats? Very little information known about the species. Probably cascading environmental factors including pastoralism and being hunting.
9. Broad-faced potoroo (Potorous platyops)
The last specimen was obtained in 1895 - or 122 years ago. Most accounts note that it was a rare species.
There is evidence for epizootic disease as the primary factor (for extinction), but probably interacting with drought and predation. (ref)
Along with disease, changes in fire regimes and increased sheep grazing are evidenced as causing this species demise.
Verdict: Caused by cats? Very little information known about the species. Probably made extinct by an introduced disease, combined with cascading environmental factors, including pastoralism.
10. Kuluwarri (Lagorchestes asomatus)
The Lake Mackay hare-wallaby is known only from a single animal collected in 1932.
Only the skull was kept, and this is the only physical evidence scientists have today for the Lake Mackay hare-wallaby's existence...
The droughts that affected Central Australia in the 1900s were responsible for a surge of forest fires which can also be attributed to the decline of the Lagorchestes asomatus. Human industrial efforts also contributed... large grass tussocks, which were used by the Lake Mackay hare-wallabies for shelter, were removed for Australia's pastoral industry. As a result, the wallabies became easy prey for eagles, foxes, and cats. (ref)
It was also hunted by Aboriginal people, who referred to it as the ‘deaf one’ and sometimes the ‘stupid one’ as it did not flush from its shelter, and could sometimes be caught by hand.
Verdict: Extinction caused by cats? Unknown and speculative at best. Probably cascading environmental factors including pastoralism and being hunted.
11. Eastern hare-wallaby (Lagorchestes leporides)
The last known species was collected in 1890, or 127 years ago.
Extinction due solely to feral cats unlikely for a mammal this size. (ref)
and
It has been suggested that an important factor in the decline of hare-wallabies has been the alteration of grassland habitat through trampling and grazing by sheep and cattle. The removal of aboriginal Australians from large areas by European settlers may also have contributed to loss of hare-wallabies by resulting in the removal of regular winter burning regimes and increasing the likelihood of devastating lightening-caused fires in summer months. (ref)
This species is believed to have been affected by the build up of sheep numbers to a record 55 million in New South Wales in 1892, and the major changes in vegetation structure and biomass that would have resulted, which left these animals vulnerable to fox predation.
Verdict: Extinction caused by cats? No. Probably instead cascading environmental factors including pastoralism.
12. Toolache wallaby (Macropus greyi)
It is believed that by 1924 the population had been reduced to one small group on a station in SA. The last known animal died in captivity in 1939.
The reason for extinction is believed to be catastrophic habitat loss, with their whole range becoming agricultural land.
Habitat loss caused not only by clearance but also by drainage of wetlands. (ref)
and
Habitat loss and fragmentation was catastrophic as the whole original range is now agricultural land. The introduced red fox and hunting contributed to the extinction. (ref)
and
A combination of numerous threats caused the decline and eventual extinction of the toolache wallaby. One of the largest factors was the destruction of its habitat. Since swamps were an important part of its habitat, once they were cleared out, much of the vegetation went with it. Besides the destruction of its habitat, the introduction of predators such as the European Fox began to kill off the species as well. On top of all this, the animal was also hunted for sport and for its beautiful pelt. (ref)
Verdict: Extinction caused by cats? No. Probably cascading environmental factors including pastoralism, land clearing and being hunted.
13. Crescent nailtail wallaby (Onychogalea lunata)
The wallaby remained common, even in agricultural districts in the south-west of Western Australia, until about 1900. It had begun a steep decline by 1908, when the last wallaby was caught in the area. The last specimen of this wallaby to be collected alive was caught in a dingo trap on the Nullarbor Plain in 1927 or 1928. W.A. Mills sent it to Taronga Zoo in Sydney and the animal ended up in the Australian Museum.
The species survived in the more arid parts of its distribution until the 1950s, and it is thought that it became extinct at about 1956, probably because of the spread of the red fox. (ref)
Habitat degradation, including changing fire regimes and the impact of rabbits and introduced stock, may have had an impact. In part of their range (south-western Western Australia and parts of New South Wales), pastoral expansion leading to habitat degradation, mainly by sheep, was likely to have been detrimental to the species.
This species was probably extirpated (eradicated) by predation from introduced foxes and cats. (ref)
Verdict: Extinction caused by cats? Probably cascading environmental factors including pastoralism causing vulnerability to fox predation.
14. Dusky flying-fox (Pteropus brunneus)
This species was found only on Percy Island off the southeast coast of QLD. The species has not been collected for nearly 160 years.
Only one specimen is known to exist. It was documented in 1859 and collected by Dobson in 1878. Since that record, no further documentation is known of this species. (ref)
and
It is possible that the species declined because of its vulnerability to habitat loss. (ref)
Timings or causation of the extinction of this species is speculative. There is a high incidence of extinction of island species caused by habitat loss and cyclones. There is also scientific debate as to whether this is a distinct species and/or native to Australia.
Verdict: Extinction caused by cats? No.
15. Lord Howe long-eared bat (Nyctophilus howensis)
This species is only known from a single skull found in 1975 on Lord Howe Island. It has never been found alive.
The only known specimen (an incomplete skull) was collected from a ledge in a cave that may have been an owl roost.
The reasons for its decline are unclear, however, it is possible that this species was predated by introduced owls and rats. (ref)
Various owl species were introduced to the island to control black rats. Owls are known to prey on bats.
Verdict: Extinction caused by cats? No.
16. Christmas Island pipistrelle (Pipistrellus murrayi)
This species was restricted to Christmas Island and went extinct in 2009.
The cause of the Christmas Island pipistrelle's decline is unknown. Several potential threats have been suggested: predation or disturbance at roost sites, and disease.
Introduced species such as the common wolf snake, giant centipede, yellow crazy ant, black rat or feral cats have all been identified as potential suspects responsible for the decline either through predation or disturbance of the bats. (ref)
and
Habitat loss and alteration, altered prey availability, vehicle related mortality, climatic conditions (e.g. cyclones, drought and associated wildfires), disease and decreasing population size may also be potential threats to this species.
The extensive clearfelling of primary rainforest for phosphate mining has reduced the roosting habitat available for the species compared to that available at the time of settlement.... a population decline was experienced by the species in the years of intensive clearing for phosphate mining. (ref)
It has also been speculated that an unidentified health threat, or poisoning from the insecticide Fipronil used to control yellow crazy ant 'supercolonies' could have been responsible for the decline which took place rapidly between 1994 and 2006.
Verdict: Extinction caused by cats? Unlikely. Instead cascading environmental factors including predation by multiple species, habitat loss, disease and/or poisoning caused the population collapse.
17. White-footed rabbit-rat (Conilurus albipes)
The last of this species was collected in about 1845. There has been no records of this species since the 1860s - or about 160 years.
Sydney natives called it 'gnar-ruck' which translates as 'rabbit-biscuit'. It was a problem in the settlers' stores at about 1788. (ref)
Rats may have spread diseases or competed for food with the white-footed rabbit rat. While the demise of Aboriginal firestick farming, which maintained woodland, may have made the rabbit rat extinct.
Previously very common and widespread, this species declined to extinction very rapidly with decline occurring across a wide range of habitats, in areas transformed by expanding pastoralism and spread of rabbits, and in areas without such modification... resource depletion and habitat change due to clearing, livestock, changed fire regimes and rabbits may have contributed to the decline in some areas. (ref)
It is assert that it “...appears to be premature to link its demise to the feral cat” and note that researchers of the time made no reference to cats being part of its range.
In some areas decline of this species coincided with establishment or intensification of grazing, and this species was also trapped and/or poisoned by settlers defending their supplies.
Once abundant, the species is believed to have vanished completely and with remarkable suddenness.
There is no evidence of disease, but the decline and extinction is believed to be so rapid and preceded most other possible threats, suggesting that disease is quite possible as a primary cause. (ref)
Verdict: Caused by cats? Most likely another threat, probably disease.
18. Capricorn rabbit-rat (Conilurus capricornensis)
Never recorded alive and only recognised as a species recently (2010), this species has only been identified by sub-fossil records so no date of extinction is listed and little is known about it.
This species has never been recorded alive, so assessment of threats is speculative. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best.
19. Lesser stick-nest rat (Leporillus apicalis)
The last two specimens were collected in 1933.
It was easily tamed, sometimes climbing onto tables to get sugar. It was also eaten by people. The last capture was filmed on 18 July 1933, when the stick-nests were set alight (and the animals captured). The specimens are held in the South Australian Museum.
The rat may have declined from competition with cattle and sheep. (ref)
and
Habitat degradation, particularly in refuges after drought, caused by introduced herbivores (mainly rabbits and sheep) before and leading into severe drought conditions. (Predation by cats) was exacerbated after habitat degradation.
Predation by indigenous predators such as dingoes and owls in combination with habitat degradation by introduced herbivores; minor on its own, but enhanced when other threats operating. (ref)
Verdict: Extinction caused by cats? Only in combination with cascading environmental factors including predation by multiple species, habitat loss, disease and/or poisoning caused the population collapse.
20. Short-tailed hopping-mouse (Notomys amplus)
This species has never been recorded alive, with the only two specimens obtained in 1896 - or 120 years ago.
Only two complete specimens were collected, probably from Aborigines. (ref)
The species was hunted, and vulnerable to habitat changes.
Verdict: Extinction caused by cats? Unknown and speculative at best.
21. Long-tailed hopping-mouse (Notomys longicaudatus)
This species was last recorded alive by two specimens obtained in 1901 - or more than 100 years ago.
The last known report of a live long-tailed hopping mouse was in 1901, when a captive individual died at an Adelaide scientific lab. The theory of the long-tailed hopping mouse's extinction was that it became extinct either due to rapid population increases in its habitat or because of over-hunting by fox, wild cats, thylacine, hawks, and owls. (ref)
There is evidence for an exotic epizootic disease as the primary factor for extinction… in many mammal species in WA. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best. Probably made extinct by an introduced disease, combined with cascading environmental factors, including pastoralism.
22. Large-eared hopping-mouse (Notomys macrotis)
Last specimen collected in 1843, or more than 170 years ago.
The Large-eared Hopping-mouse’s habitat, loamy valley soils with grass, was used for sheep herding at the time of extinction; this would have degraded its habitat and collapsed its burrows.
There is evidence for an exotic epizootic disease as the primary factor for extinction… in many mammal species in WA. (ref)
and
The hopping mouse was probably the first Australian mammal to succumb to European settlers. Hopping mice are vulnerable to agriculture and pastoralism, as well as introduced cats...
This mouse's extinction can possibly be shown as a ramification of environmental alteration by humans, and predation is another likely possibility, but the true reason for the extinction of the big eared hopping mouse is unknown. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best.
23. Darling Downs hopping-mouse (Notomys mordax)
Known only from a single skull without skin collected in the 1840s.
Burrows and food would have been damaged by stock.
and
Clearing and cropping would have destroyed burrows. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best.
24. Broad-cheeked hopping-mouse (Notomys robustus)
This species was never collective alive, but is believed to have become extinct around the 1860s or 1870s, or around 150 years ago.
The great hopping mouse (Notomys robustus) is extinct. It is known only from skulls found in owl pellets in the Flinders Ranges. (ref)
and
There was a major drought in the Flinders Ranges region between 1864 and 1866, a time when there was significant overstocking of sheep; many indigenous mammal species never recovered. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best.
25. Long-eared mouse (Pseudomys auritus)
This species is only described from specimens collected in the 1800s, or over 200 years ago.
Habitat was seriously overgrazed soon after settlement (ref)
and
Preferred habitat was probably periodically-inundated areas adjacent to swamps. Much of this habitat was cleared for agriculture. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best.
26. Blue-gray mouse (Pseudomys glaucus)
The Blue-grey Mouse is listed as Extinct because it is known only from three specimens: two collected before 1892, when they were presented to the Natural History Museum, London, and one accessed by the Australian Museum, Sydney, in 1956; surveys have failed to locate it.
Almost nothing is known of this species. (ref)
and
Habitat loss and fragmentation - severe catastrophic - entire - most of presumed former range is cleared.
(Cat predation) possibly a secondary causal factor after land clearing and fragmentation and degradation of remaining habitat. (ref)
Verdict: Caused by cats? No. Probably instead cascading environmental factors including pastoralism.
27. Gould’s mouse (Pseudomys gouldii)
This species has not been collected alive since 1856 - or more than 160 years ago.
Gould's mouse was common and widespread before European settlement, but disappeared rapidly after the 1840s, perhaps being exterminated by cats. Alternatively, it may have been out-competed by the introduced rats and mice, succumbed to introduced diseases or been affected by grazing stock and changed fire regimes. Despite extensive survey work in its known range, the last specimens were collected in 1856–57, and it is presumed to be extinct. (ref)
Verdict: Extinction caused by cats? Unknown and speculative at best.
28. Bramble Cay melomys (Melomys rubicola)
This island species was
The first substantial report on its status in 1983 considered that its population was at least several hundred individuals. It declined either gradually or episodically subsequently, although there were few and not very robust estimates of its status. It is likely that decline occurred due directly to storm surges across the entire island (killing individuals) and/or ongoing and episodic reduction in vegetation (probably also due to storm surge). (ref)
and
This island species of a few hundred individuals, is restricted to a single small island off the coast of QLD. The island is vulnerable to storm surges and tsunamis.
There are no cats currently on the island. (ref)
Verdict: Extinction caused by cats? No. Likely environmental.
29. Maclear’s rat (Rattus macleari)
This island species only appeared on Christmas Island and became extinct within 20 years of discovery, with the last animal recorded in 1902.
Andrews (1909) speculated that introduced Black Rats Rattus rattus had brought an epidemic disease to the island that wiped out both native rats. Nearly 100 years later, the mystery was finally solved by Wyatt et al. (2008), who used ancient DNA methods on samples from museum specimens of these rodents collected during the extinction window (AD 1888–1908), and showed that endemic rats collected prior to the introduction of Black Rats were devoid of evidence of a pathogenic trypanosome (carried by fleas hosted on recently-introduced Black Rats).
To Andrews, the disappearance of such an abundant animal in such a short time had to be due to disease because R. rattus was not present over the entire island. It was unreasonable therefore to assume that the native species had been out-competed by R. rattus all over the island.
Two predators had been introduced to the island by 1908, cat and dog, but these were far too few to rid the island of the rats. Although Christmas Island had an increasing human settlement at Flying Fish Cove, roads now crossed the island, and there was active phosphate mining, there was still a lot of native forest and even collectively these human disturbances were unlikely to have caused significant declines in the populations of Maclear's Rat (Andrews 1909). Andrews (1909) also relates anecdotal information that a medical officer on the island, Dr. McDougal, recalled frequently seeing "individuals of the native species of rats crawling about the paths in the daytime, apparently in a dying condition" in 1902-1904. (ref)
Verdict: Extinction caused by cats? No. Likely a disease.
30. Bulldog rat (Rattus nativitatis)
This island species also only appeared on Christmas Island and became extinct within 20 years of discovery, with the last animal recorded in 1899.
The demise of the Bulldog Rat was certainly rapid, going from locally common to extinct in less than eight years. It is thought to have been the result of an epidemic disease brought to the island by introduced Black Rats R. rattus (ref)
Verdict: Extinction caused by cats? No. Likely a disease (see above).
And finally, a note about birds
Only one Australian endemic bird species has become extinct from mainland Australia since European settlement (i.e., about 0.3% of Australian land birds), a far smaller number and proportion than for mammals. (ref)
If you've managed to read all the way through this document, one thing should be clear. If we're going to advocate for the removal of cats from our landscape as based on this "22 extinct" mammals statistic, we need to give even more credence to the notion of the complete and total removal of sheep and cattle from the landscape also, as these species not only caused the environmental cascades which lead to cats being deemed a "problem" - but that continue to keep Australia from returning to the "natural" state so prized by the environmentalists leading the charge against cats.
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References
Mammalian faunal collapse in Western Australia, 1875-1925: the hypothesised role of epizootic disease and a conceptual model of its origin, introduction, transmission, and spread - http://publications.rzsnsw.org.au/doi/pdf/10.7882/AZ.2006.024?code=rzsw-site
Disease as a primary factor is considered to provide a more satisfactory explanation of early declines in WA than predation by feral cats. Species affected by disease Most records of species decline explicitly (though speculatively) linked to disease were of the most conspicuous species, namely Trichosurus vulpecula, Bettongia lesueur, B. penicillata, Setonix brachyurus, Pseudocheirus occidentalis, and Myrmecobius fasciatus. There were also numerous records of early declines of these species without them being linked explicitly to disease. A few records stated that ‘all small marsupials’, ‘marsupials’ or ‘all rodents’ had disappeared as a result of disease.
The Action Plan for Australian Mammals 2012
http://www.ebooks.com/1702486/the-action-plan-for-australian-mammals-2012/burbidge-andrew-harrison-peter-woinarski-john/