Cats and dogs are being accused of contributing to a devastating wildlife decline. Recent research from America, revealing that cats kill up to 3.7 billion birds and 20 billion mammals each year, has raised questions about the impact of the UK’s nine million cats on our wildlife.

A Mammal Society report conducted a decade ago found that UK cats kill 275 million prey items each year, with 55 million of these being birds. House sparrows, blue tits, blackbirds and starlings sit at the top of a cat’s bird menu.

These figures seem enormous but, argue the RSPB, many millions of birds die naturally each year through starvation, disease and other predation.

Cats are non-native and in urban areas they are often kept at unnaturally high densities, making them by far the most numerous predators in the UK — a fact that does concern some wildlife groups.

Laura Drake, surveys co-ordinator at The Mammal Society, said: “Cats are a predator in our ecosystem, which unlike wild predators are not controlled by wild prey numbers.

“Domestic cats have an additional in-house food source, so they are not limited by the number of birds and mammals in the local environment.

“Therefore if the population becomes great enough in one neighbourhood for example, they may have an impact on the local wildlife populations.”

The presence of two particular birds on the cat hit-list has caused concern. House sparrow populations have collapsed by a staggering 71% between 1977 and 2008, resulting in this once ubiquitous bird being classed as a red list species — a status reserved for birds of the highest conservation priority.

Starlings have suffered a similar fate, with declines meaning this much-loved garden favourite has also been added to the red-list.

Changes in urban habitat are cited as a major reason for these declines, but could the added pressure of an expert predator kept at unnaturally high levels be adding unwanted pressure upon our struggling sparrows and starlings?

The RSPB insists that there is “no clear evidence” linking the declines of sparrows and starlings to domestic cat populations at present.

But many wildlife lovers believe enough is enough and have called for action to reduce the impact of our feline friends. Cats hunt mainly from dusk to dawn; research suggests if they were prevented from going out at night, then far fewer birds and mammals would be killed.

The Mammal Society and naturalists, including Springwatch presenter Chris Packham, have called for cat curfews to be put in place to stop cats going out on the prowl during the small hours.

Ms Drake said: “Cats are expert hunters, but we must not demonise the animal itself.

“The Mammal Society strongly advocates responsible cat ownership to include spay and neutering, keeping them in at night if practical, placing a bell on their collars, getting cats from rescue centres as opposed to breeders, and limiting the number of cats per household to one or two.”