By Tracy Brighten
Australia has pledged to tackle the soaring feral cat population that threatens more native animals with extinction
With 1800 nationally listed threatened species, the Australian Government has set targets for conserving 30 priority plant species, 20 mammals and 20 birds.
“That means humane culling of one of our wildlife’s worst enemies – feral cats,” said Minister for the Environment Greg Hunt in a statement.
Hunt presented Australia’s first national strategy for threatened species at the Threatened Species Summit, which he hosted to discuss native animal and plant conservation. Delegates included state and territory ministers, business leaders, scientific and conservation experts, and non-government organisations.
Each day, feral cats are killing an estimated 75 million native animals—that’s more than 20 billion mammals, birds and reptiles each year.
“Feral cats have contributed to the extinction of at least 27 mammal species. We don’t want to see that number grow,” said Hunt.
Feral cats are descendants of domestic cats introduced by European settlers. Originally beneficial around farms and homesteads to control rabbits, rats and mice, feral cats are now out of control. On Australia’s mainland and islands, feral cat numbers are estimated at 15 to 23 million.
Chris Johnson, professor of zoology at the University of Tasmania, said there is evidence that many species disappeared during the early colonisation of Australia by the British. “The leading candidate for that cause, I think, is the feral cat,” he told ABC Radio.
Conservation biologist Dr John Woinarski supports this suggestion, having studied animals in the Northern territories in the late 1980s, before the latest surge in extinctions.
“It was effectively a paradise for a zoologist, and then over the course of a decade we were getting less and less in our traps, until by about 2000, 2010, we were coming back with almost nothing,” he told ABC Radio.
What are feral cats eating?
Ecologist Dr John Read has dissected more than 1,000 feral cats over 25 years after trapping or shooting them in the South Australian desert. Talking to ABC Radio, he described stomach contents that reveal an opportunistic predator.
“[Feral cats] eat falcons and cockatoos, bats, centipedes, scorpions… virtually every lizard, every snake, every frog, every bat, just about every bird in Australia and any mammal smaller than a large kangaroo, at least when they are joeys, are all susceptible to cat predation.”
Successful implementation of the five-year plan with practical actions, measurable targets, and accountability will require co-operation and collaboration across all sectors of society.
The proposed actions are to reduce numbers of feral cats, create safe havens on islands and the mainland for species most at risk, improve habitat, and intervene to prevent extinction.
Australia’s first threatened species commissioner, Gregory Andrews, emphasised the strategy was not about hating cats but about not tolerating the impact of feral cats on wildlife.
Priority species for protection
The numbat, mala and greater bilby are included in the first 10 mammals selected for priority action, and the first 10 birds include the helmeted honeyeater, Southern boobook owl and Norfolk Island green parrot.
Hunt also identified the Western ground parrot and the orange-bellied parrot for conservation action, “I want future generations to enjoy the colour, movement and song they bring to our lives,” he said.
BirdLife Australia’s State of Australia’s Birds 2015 report, compiled from 15 years of data, provides a Bird Index that reflects the health of the environment in the same way that the Consumer Price Index measures the economy.
The report states that 144 of the 1241 bird species and subspecies found in Australia are considered threatened according to the International Union for Conservation of Nature, with 18 species categorised as critically endangered and on the brink of extinction.
The Southern boobook owl is in significant decline in every Australian region except one, and the well-known laughing kookaburra is in decline in south-eastern Australia.
It’s not just about preserving biodiversity either. Bats and birds help to control pest insects and to maintain forests by spreading seeds. Native animals and plants are also important to a nation’s identity and culture, to a healthy environment and to the economy by way of tourism.
Feral cats will be targeted through baiting, shooting and poisoning. Just $6.6m has been allocated to the Threatened Species Strategy, with the majority of the money focused on cat eradication. Hunt would like to see additional funding for the plan from private and public organisations.
Although environmental groups welcomed the government’s new strategy, some were concerned about the low level of funding and the lack of stricter controls on habitat loss.
Why is the feral cat cull imperative?
People may argue that a cull of feral cats to protect native wildlife is interfering with the ‘survival of the fittest’, but humans upset the natural balance by introducing non-native animals. When predators are introduced, native animals may not adapt in time to survive, especially if the predator breeds quickly and has few or no predators.
There will also be those who believe it’s hypocritical of humans to kill feral cats to protect endangered species when humans are guilty of species extinction. But if we take this view, we will simply increase our guilt by not having prevented further species extinction. We can restore the balance in the most humane way possible.
Culling is always an emotive issue, and with viral cat videos, the cat bug is spreading faster than feral populations. But we need to be objective. Feral cats are not domesticated—hey are formidable killers. They don’t hunt wildlife for an extra treat on top of their Whiskas; they hunt to survive. Life as a feral cat is a far cry from life as a domestic cat. Feral cats can suffer disease, injury and starvation.
Threat of toxoplasmosis infection
Cats also carry the Toxoplasma Gondii parasite that can cause toxoplasmosis in mammals and birds. Disease transmission can be water- or food-borne via oocysts excreted in cat faeces. Oocysts can survive in the environment for up to 18 months, capable of infecting long after the cat has gone.
Over 6 million people have been infected worldwide. Toxoplasmosis can cause retinal infection and blindness and can be life-threatening in people with compromised immune systems. When pregnant ewes become infected, they usually suffer an early abortion.
University of Tasmania’s Bronwyn Fancourt reports that Australian marsupials are highly susceptible to toxoplasmosis. Fancourt says that infected animals are either found dead or stumbling around blindly during the day, at risk to predators or cars. In New Zealand, Massey University pathologist Dr Wendi Roe has linked feral cats to toxoplasmosis infection in Hector’s dolphins via estuaries and coastal waters where dolphins feed.
There is some evidence that culling may not be effective when culled feral cats are replaced by neighbouring cats. Any culling plan needs to be carefully targeted, monitored, and maintained to ensure that culling outstrips breeding.
Controlling the feral cat population will only be effective alongside other measures, such as preventing feral recruitment from domestic and stray cat populations through continued neutering. Australia is also considering a policy of keeping domestic cats indoors. Red foxes are also a native wildlife predator and population control must be maintained.
Hunt invites all Australians to play their part in native animal and plant protection. “As Minister for the Environment, I am drawing a line in the sand and asking the community to join me.”
Humans caused the global feral cat epidemic by introducing domestic cats. Now is the time to redress the balance. Australia must be commended for taking a strong and potentially controversial stand to protect its diverse native species.
Southern boobook at night by A. Lumitzer
Another Eye by Acechando. Licensed under CC BY-NC-SA 2.0
Numbat by Martin Pot (Martybugs at en.wikipedia). Licensed under CC BY 3.0 via Wikimedia Commons
Norfolk Island green parrot by George Chapman.Licensed under CC BY-NC-ND 2.0
Southern boobook owl by Brisbane City Council. Licensed under CC By 2.0(https://en.wikipedia.org/wiki/File:Boobook_(7126975261)
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