The next sound you hear will be from one of the world’s more ferocious animals, an invasive species in these parts, a vicious killer responsible for the predation of billions of wild birds:
Meow? As in, the meow that is so often the response to “here kitty, kitty?”
Yup, that meow. The call of the house cat, “felis catus” to the scientist, beloved companion to millions of Americans, including hundreds of thousands of Vermonters. The cats that crawl onto their owner’s laps in the evening in front of the fire, purr when scratched behind the ears, and make children laugh by leaping about.
And kill birds.
How many birds? Billions, roughly 2.4 billion a year nationwide, says a new study by credentialed scientists from the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service writing in a prestigious, peer-reviewed journal.
No way, says a cat-lovers organization.
“This doesn’t appear to be research for research’s sake,” said Becky Robinson, co-founder and head of Alley Cat Allies. Not only do the “extreme numbers seem quite exaggerated,” she said, but the authors wanted to “further their agenda to kill more cats.”
Whether or not the study -- “The impact of free-ranging domestic cats on wildlife of the United States” – is part of it, there is an agenda of sorts here, a low key but unmistakable campaign being undertaken by environmentalists in alliance with federal and state (including Vermont) agencies to spread awareness about bird predation by cats.
Buck didn’t suggest killing more cats, but Becky Robinson was not entirely wrong. Though it hardly advertises it, one of the aims of this quiet campaign really is to kill more cats.
“Unless adoptions increase, it's hard to avoid euthanasia” as one possible option in the effort to protect birds, said Rosalind Renfrew, a conservation biologist at the Vermont Center for Ecostudies. Even more bluntly, the respected (if often controversial) environmental writer Ted Williams wrote that the most “effective, humane alternative” for both birds and cats was “to trap and euthanize.”
No, not little Tabby sitting on a lap in front of the fireplace. That’s a pet, an “owned cat,” in the jargon of this discussion. No one wants to kill him or her.
The cats effectively marked for death by this persuasion campaign are the strays, the wild or feral cats that are responsible for 70 per cent of the cat-caused bird deaths according to that disputed study.
In Vermont, at least, pet cats would seem to outnumber their feral cousins. According to the American Veterinary Medical Association, Vermonters are more likely to have a cat than the residents of any other state. Seventy percent of Vermont households have a pet, the Association said, with just about half the households owning one or more cats.
Though pets don’t kill as many birds as feral cats, the bird-protectors have advice – or perhaps it’s more like a command – for their owners..
“Keep your cat indoors,” said Mark Labarr, a conservation biologist at Vermont Audubon, echoing the message of the Fish & Wildlife Department and other environmentalists.
Not only will a cat kept inside not kill birds, LaBarr said, “it will probably live longer.” Inside, a cat cannot be run over by a car or eaten by an owl or coyote. LaBarr said research shows a cat kept inside is likely to live four or five times longer than one allowed outdoors.
The authors of the report – actually a compilation and assessment of earlier research – published in January in “Nature Communications” an on-line scientific journal, acknowledge that their figures are not exact. “The magnitude of mortality…remains speculative,” they say, but their “systematic review” of all the available evidence leads to the “estimate that free-ranging domestic cats kill (between) 1.4 (and) 3.7 billion birds…annually.”
What this means, the authors conclude, is that cats “are likely the single greatest source of anthropogenic (human-caused) mortality for US birds.”
Robinson, who said habitat loss reduces bird populations more than does predation by cats, said her organization hired an “independent” statistical analyst, Gregory Mathews of the University of Massachusetts at Amherst, to review the report. Mathews found “numerous major flaws in the statistical analysis.”
But “Nature Communications” has a transparent and apparently rigorous editing and peer review process. The study by the Smithsonian and Fish and Wildlife scientists was submitted in September, but not accepted until mid-December. Other organizations, including the American Veterinary Medical Association, are treating its results as valid.
It is hardly news that cats kill birds. But why, all of a sudden, would they be killing so many that this predation has become a problem?
Perhaps, suggests Rosalind Renfrew, because there are so many more cats. Recent research, she said, showed that “40 years ago there were 30 million pet cats in (American) homes. It’s tripled. There are now about 90 million.”
What makes this more dangerous for birds, she said, is that “birds did not evolve with cats.” So while other animals eat birds, those animals and the birds reached natural population equilibrium. Cats are not part of that process. They were brought here by people, with the potential to upset the equilibrium.
“It’s what cats do,” said Renfrew, explaining that making sure a cat is well-fed before letting it out won’t keep it from trying to catch birds.
Mark LaBarr acknowledged that convincing cat owners to keep their “revered pets” inside can be “a tough one. It’s difficult to talk to some people about that, even though it means they’ll have lower vet bills.”
Experts say that city and suburban cats probably kill more birds than do their rural counterparts. In rural areas, more birds are likely to stay in the forests, where cats rarely wander. Rural cats might also stay closer to home because they are in more danger from predators.
But the standard Vermont barn cat cherished by so many farmers as rodent control agents qualify as “free-ranging domestic cats” that feed on birds. According to Anne Ward of the Central Vermont Humane Society in Montpelier. those barns are home to the typical Vermont feral cat colony. The way to control them, she and other cat-lovers insist, is TNR – trap, neuter, replace. As the sterilized cats die off, the colonies should dwindle.
Here is the crux of the scientific debate. Most environmentalists find that TNR has been a failure. “It has largely been unsuccessful,” said LaBarr. And Ted Williams called TNR “a dangerous, cruel, and illegal practice” harmful to both cats and wildlife.
But Joanne Bourbeau, the former Vermont Director of the Humane Society of the Untie States, insists TNR is working in Vermont, where “fewer and fewer cats are being brought into shelters.”
Becky Robinson insisted that it is euthanasia that has failed.
“We’ve been catching and killing for a century,” she said, “wasting millions of dollars of taxpayers’ money. TNR works.”
But even TNR advocates acknowledge that it will only work if pet cats cease “migrating” to the feral colonies, and Anne Ward noted that in Vermont “there’s a lot of dropping off of non-feral cats in those barns” instead of taking them to shelters.
TNR has been practiced for about 20 years, Robinson said. Considering that a cat in the wild has a life span of only a few years, if TNR were as successful as it supporters claim, most feral cat colonies would be almost gone by now.
Though they are reluctant to say so this bluntly, the bird protectors believe that euthanizing the invasive feral cats – many of them disease-ridden and malnourished – is a small price to pay to protect and preserve native wildlife.
In an animal-loving country, that’s not an easy argument to make.
What do you think? Are you for the birds or the cats? Or do you think they can all get along?