Tuesday, February 5, 2019

A bird and a half a day. Cats and bird deaths—an inflated fact?

Photographer friend Jerry Downs posted a lovely photo of an orange spotted housecat sitting on a car hood enjoying a rare bit of sunshine in an otherwise bleak and rainy week. And of course someone had to go and spoil it all by stating how every outdoor cat was responsible for 500+ songbird deaths in North America. (To the tune of  3.6 million birds a day, or 1.3billion birds a year). A bird and a half a day per cat? Do the math. Who comes up with this stuff?

To wit, I replied—The cat bird kill thing is somewhat inflated....that would be something like a bird and a half per day per cat. I don’t think so. Besides, not all free roaming house cats kill birds. In fact, most pet cats are clumsy lummoxes. Easy targets like mice run in front of their noses and they hardly know what to do with them. They’re not the ferocious hunters they’re cracked up to be. Besides the males (he’s orange, therefore, has an 80% chance of being male) rarely, if ever, hunt.

But when it comes to birds, people’s free range pet moggies are unfairly bearing the brunt—convenient scapegoats for bird deaths. Instead look to climate change, bird habitat loss, exposure to chemicals, fertilizers, insecticides, and collisions with man-made objects—from cell towers airplane engines to to cars to windows. A billion birds a year die from colliding with windows. Human impact is the real threat" to songbirds.

We’ve also systematically killed off most of the wild birds’ natural predators—from kestrels and hawks to bobcats to coyotes and wolves— which was never factored in on the annual estimated bird population death counts. That said, I’m not for vast colonies of feral cats. They don’t belong here. They should be eradicated. But when someone’s pet moggie sitting outside on a car hood enjoying a spot of sunshine, being held responsible by proxy for massive bird deaths, is a bit over the top. Talk about killjoy.

Should you happen to have a free range moggie with a taste for fowlish feathers friends, there’s an app for that, a splashy Elizabethan style collar ruff that the birds can see a mile away. According to the Atlantic article, there are 8.4 million pet cats, and 4.6 million of hem have outside access. That does not mean they are all catching birds, that’s an assumption being made. Besides, it’s not  measurable. The article states that the feral cat population in the US is somewhere between 30 and 80 million cats. I’d suspect that they are the real culprits. The estimates are as flagrant as the Powerball meme circulating on Facebook. So let’s play with the math. Suppose all 34 to 84 million cats were successful bird hunters, now divide that number (both high and low estimates) by 1.3 billion. You can see that the claims are impossible—even if you can’t do the math.

1,000,000,000 (one billion) is 100 million.
1.3 billion dead birds / 4.6 million hungry pet cats
(most are unlikely to bag more than a bird or two in a lifetime). = 282.60896
1.3 billion / 4.6 million / 365 days = .77 birds a day
(but we still need to add in the estimated feral cat population)
1.3 billion / 34.6 million total cats, both feral and domestic low estimate = 37.5722543
1.3 billion / 34.6 million / 365 =  .10 birds a day per cat
1.3 billion / 84.6 million total cats, high estimate = 15.36643026
1.3 billion / 84.6 million / 365 = .04 birds per day per cat.

Outdoor cats kill between 1.4 billion and 3.7 billion birds a year, study says Researchers estimate one pet cat kills between one and 34 birds a year, while a feral cat kills between 23 and 46 birds a year.

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