Cats And The Decline Of Garden Birds
According to the Mammal Society, cats kill up to an estimated 275 million prey a year in the UK, of which 55 million are birds. This is the just the number that were known to have been caught and does not include prey that cats didn’t bring home, or that escaped and subsequently died.
The birds caught most frequently are house sparrows, blue tits, blackbirds and starlings.
Despite this, there is no scientific evidence that cats are having any impact on bird populations in this country as many millions of birds die naturally each year, mainly through starvation or disease, or at the hands of other predators. It is believed that cats tend to take weak or sick birds and it is likely that most of the birds killed by cats would have died from other causes before the next breeding season.
Millions of baby birds are hatched each year and most of these will die before they reach breeding age. Again, this is quite natural and each pair only need to rear two young that survive to breeding age to replace themselves and maintain the population.
The species of birds that have undergone the most serious declines in populations in the UK, such as tree sparrows, skylarks and corn buntings, rarely encounter cats, so cats cannot be causing their decline. Research has shown that these species are declining due to a change or loss of habitat, particularly on farmland.
Some populations of birds that are most abundant in gardens are actually increasing, despite the presence of cats. For example, blue tits which are believed to be the second most frequently caught bird have increased by over a quarter since 1966. Of those frequently caught by cats, only house sparrows and starlings have suffered a decline in breeding populations.
However, it is still prudent to try and reduce cat predation as gardens provide a breeding habitat for at least 20% of the the populations of house sparrows, starlings, green finches, black birds, and song thrushes, some of which are declining in numbers.
If you have a problem with cats killing or frightening birds in your garden then you may wish to invest in a cat deterrent to try and prevent them from coming into your garden.