This post was triggered by a small item a few days ago in The International New York Times about feral cats in Australia which, according to the latest genetic evidence, are the descendants of cats brought over by European settlers in the 19th century.
There are now an estimated 20 million feral cats which prey on more than 100 of the country's native species and have, its claimed, helped drive at least 27 species to extinction. Government plans to cull two million cats met with an international outcry.
Brigitte Bardot called it "inhumane and ridiculous". Morrissey wrote: “We all know that the idiots rule the earth, but this is taking idiocy just too far. The cats, who keep the rodent population under control, will be killed in a ferocious manner, using Compound 10/80, which is a gut-wrenching poison of the most unimaginable and lengthy horror.
“The people of Australia would never agree to this – but of course they will not be consulted, because the Australian government as ruled by Tony Abbott is essentially a committee of sheep-farmers who have zero concerns about animal welfare or animal respect. The cats are, in fact, 2m smaller versions of Cecil the lion [the famous Zimbabwe lion killed by an American dentist.]
A spokeswoman for Australian Environment Minister Greg Hunt said that feral cats were the biggest threat to more than 120 endangered species in Australia. “With around 20m feral cats in Australia and with each feral cat estimated to kill at least five native animals a day, they pose an enormous threat to our native species. The government has invested $4.1m in developing humane, target-specific feral cat bait called Curiosity. The toxin in Curiosity works in a way that is similar to the cat falling into a deep sleep and not waking up.”
This figure comes from a three-year US Fish and Wildlife Service funded survey, published in the journal Nature Communications (January 2013) aimed at estimating the number of birds killed by predators, chemicals and collisions with wind generators and windows.
About a third of the 800 species of birds in the USA are endangered, threatened or in significant decline, according to the American Bird Conservancy.
The survey estimates that cats kill 1.4 billion to as many as 3.7 billion birds in the continental U.S. each year and, incidentally, also 20.7 billion mammals — mainly mice, shrews, rabbits and voles. The survey uses the term "unowned" cats to refer to farm cats and strays and feral cats, which often live in colonies.There are an estimated 300 outdoor cat colonies in Washington, D.C. alone.
So what about the situation in the UK. According to 2015 figures from the Pet Food Manufacturers Association (PFMA) there are 7.4m domestic cats in 17% of households in Britain. The feral cat population of Britain, in a 2009 study by the Game & Wildlife Conservation Trust in 2009, was estimated at 813,000.
To balance these figures out and to get a clearer picture of this emotional topic let's turn to a reliable and up-to-date source The Royal Society for the Protection of Birds (RSPB):
'The most recent figures are from the Mammal Society, which estimates that the UK's cats catch up to 275 million prey items a year, of which 55 million are birds. They estimate the most frequently caught birds are probably (in order) house sparrows, blue tits, blackbirds and starlings.
'Despite the large numbers of birds killed, there is no scientific evidence that predation by cats in gardens is having any impact on bird populations UK-wide. This may be surprising, but many millions of birds die naturally every year, mainly through starvation, disease, or other forms of predation. There is evidence that cats tend to take weak or sickly birds.
'It is likely that most of the birds killed by cats would have died anyway from other causes before the next breeding season, We also know that of the millions of baby birds hatched each year, most will die before they reach breeding age. This is also quite natural, and each pair needs only to rear two young that survive to breeding age to replace themselves and maintain the population.
'It is likely that most of the birds killed by cats would have died anyway from other causes before the next breeding season, so cats are unlikely to have a major impact on populations. If their predation was additional to these other causes of mortality, this might have a serious impact on bird populations.
'Those bird species that have undergone the most serious population declines in the UK (such as skylarks, tree sparrows and corn buntings) rarely encounter cats, so cats cannot be causing their declines. Research shows that these declines are usually caused by habitat change or loss, particularly on farmland.
'Populations of species that are most abundant in gardens tend to be increasing, despite the presence of cats...Gardens may provide a breeding habitat for at least 20% of the UK populations of house sparrows, starlings, greenfinches, blackbirds and song thrushes, four of which are declining across the UK.
'For this reason it would be prudent to try to reduce cat predation, as, although it is not causing the declines, some of these species are already under pressure. Cat predation can be a problem where housing is next to scarce habitats such as heathland.'
The US survey quoted above estimated that wind turbines kill between 214,000 and 368,000 birds annually. See my extensive previous post on this subject: http://hqinfo.blogspot.co.uk/2012/11/bird-collision-deaths-wind-farms.html