Forget the BBC article; here is the American Bird Conservancy, with a link to the actual paper.
You cannot compare natural predator impacts to anthropogenic sources of mortality to justify those anthropogenic sources. Any domestic cat mortality is an additional impact that would not otherwise occur.
From: Vermont Birds [mailto:[log in to unmask]] On Behalf Of Jane Stein
Sent: Wednesday, January 30, 2013 1:19 AM
To: [log in to unmask]
Subject: Re: [VTBIRD] bbc article on cats/birds-wildlife - (long)
Richard, please don't make up your own stories about what I think or do.
Here's what I know that makes me skeptical of this and other similar articles. First, any naturalist will tell you there's far, far more damage done to ground-nesting birds in both woods and fields by coyotes, foxes, racoons and other small to medium-sized predators and omnivores whose population is way too high because of the absence of top predators, like wolves, to keep their numbers down.
It isn't primarily nest-sitting birds that are killed, it's eggs, and when nests are destroyed, birds often don't come back to try again.
These wild critters love eggs and seek them out. They destroy far more ground nests than any cat, which unlike them, typically have no idea what to do with an egg. I used to know and work with several refuge managers for small suburban refuges, and none of them ever mentioned their not uncommon cat visitors as a problem, but became apoplectic on the subject of dogs, which trample nests out of curiosity more than actually eat eggs, and egg-eating raccoons, etc.
I intensely dislike killing things, even spiders in my kitchen and wasps nesting over my door. But there comes a point when it's them or me, and I'm afraid I choose me. (I have it on fairly good third-hand authority, btw, that even the Dalai Lama's household is unkind to mice. I asked because I remain troubled about the issue.) Yes, mice are pests when they chew their way into your house and cupboards and leave their feces all over your kitchen and pantry or chew holes in your potato crop before it's even harvested.
Urban sprawl and forest fragmentation, I whole-heartedly agree, is the major problem here. But it's not because of housecats, it's primarily from the devastation of the habitat itself, secondly the presence of coyotes and raccoons attracted to human garbage.
We can argue all day about cats, but articles like this BBC one are just not honest in their attempt to portray housecats as having a devastating effect on "wildlife," which conjures up horrible images, but then not telling you until the very end that they're talking about mice and other creatures so abundant and with such a reproduction rate that it would take 100 times as many cats as there are now roaming around to make a dent in them, and then that it's feral cats that do the most damage anyway. That's called "burying the lead" in journalism, and it's not being straight with readers.
What this kind of thing does, IMO, is let us in our too easy anger at very visible cats forget about the things that are doing the real
damage-- as you say, human development and forest fragmentation, which would be just as devastating even if there were no cats at all. Far more damage is done to bird populations by cowbirds allowed in by forest fragmentation, not to mention the rapidly shrinking winter habitat and staging areas along the way for migratory birds.
As for prey for hawks and owls, it's coyotes and foxes that do the most damage there, though still not enough to make very much of a dent. You might find it interesting to look up what's happened at Yellowstone since they introduced wolves and the populations of both those smaller predators dropped way down. Among other things, yes, the hawks came back, and also the nesting habitat for birds that had been destroyed by deer browsing.
They've seen the same thing at Plum Island in Mass., where for a while wintering Rough-Legged hawk numbers dropped dramatically when both coyotes and foxes, I think, moved in and the refuge staff held off on killing them because of public distaste for the idea. There were no cats in either place.
Also, the primary mouse and vole-eating raptors in this country have stable or increasing populations, with only two exceptions that I know of, one being the Ferruginous Hawk out west, the one that came back to Yellowstone, and the Kestrel. Neither one is in trouble because of food insufficiency.
I've also seen very vividly here that when the local hunters go on one of their periodic coyote slaughtering parties, the population of both rabbits and voles absolutely explodes for a year or so until the coyotes build their numbers up again.
Against all this, cat predation is insignificant, if we're talking about actual effects on populations.
By all means, do what you can to get neighbors to keep their cats in where you're having a problem, or even work for a city ordinance. I'd help you. I wouldn't have a cat that needs to be outdoors in the city or even most suburbs. But it really does seem to me the issue is someone's desire to have unmolested feeder birds to watch versus the neighbor's desire to let his cat spend time outdoors. That's a volatile issue, but it isn't a conservation issue.
I looked up, by the way, endangered species of rabbits and other rodents in North America, and couldn't find one where cat predation was cited as even worth mentioning. If there are places where it is, I'd favor some kind of vigorous local, state or even federal action to restrict, trap and remove, or even ultimately kill cats.
All I'm arguing for here is that we look maybe more calmly at the facts.
Those are the relevant facts that I know of. Given all those things, I'm more than a little bit skeptical of the scare stories that pop up periodically, especially because they tend to be published, as this one was, as scare stories and not reasoned ecological discussions and the role cats may or may not play in them.