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Sunday August 18, 2019
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bird bath with dead birds

A Murder of Crows

The birdbath as meat locker

by Margaret A. Leary

From the July, 2019 issue

Lifeless creatures began to show up at my house, in ways they never had before, the day after I saw the movie Coco last summer. Inspired by the Mexican holiday the Day of the Dead, Coco is about a twelve-year-old boy who is accidentally transported to the Land of the Dead and struggles to find a way to return to the living.

First my ancient, arthritic cat, who could barely walk, let alone hunt, showed up with a dead bird in her mouth. I discarded it. Ten minutes later she reappeared with a barely alive bird. I learned long ago not to "rescue" such prey and ignored it.

The next morning, a small squirrel seemed to cling to the outer, upper corner of a screen door. It dropped dead to the ground when I opened the door.

But the birdbaths were the worst. Each of the six in my yard yielded up often-unrecognizable pieces of birds, small mammals, and bits of what was perhaps a snake. One birdbath held a small beaked skull and a feathered chest. Another stored chunks of unidentifiable flesh and a small spine. The water was murky with rot. What was going on?

Then I saw a lustrous crow pull something out of the water, place it in under a claw, pull off a tasty morsel, and flap off victoriously.

Cleaning the birdbaths was nauseating. If the water evaporated enough to leave some of the victim dry, flies covered it. The remains stank, and some stuck so firmly to the birdbath's sides and bottom as to require power-washing.

Local landscaper Chris Graham confirmed that June is "bird baby and birdbath time again!" For a longer explanation, I used the website of Cornell University ornithologist Kevin McGowan. There I learned that male crows (and their relatives in the Corvidae family) store food to bring to the female sitting on their eggs; later, the adults store food for their nestlings.

The birdbath-as-fridge is disgusting but clever: the water keeps flies

...continued below...


away, keeps the meat moist, and eases the task of removing inedible parts like feathers. McGowan suggests: "Perhaps they want it to rot a little to improve the flavor … just as we 'age' beef."

I also learned that crows mate for life and form strong communities, roosting at night in large groups and flying off in search of waste grain during winter days. The young stay near their parents for several years before finding a mate and help raise the next broods-sometimes bringing food to the nestlings.

"Crows will eat anything they can subdue," McGowan writes, mostly grain in winter and earthworms and other invertebrates in spring and summer. They also eat eggs and nestlings of other birds and "in some areas might have a significant impact on a local population of birds."

Ann Arborites might immediately leap to the conclusion that crows are in a class with deer: that they are negatively affecting desirable species and ought to be "culled." Might we need a crow cull to protect robins, cardinals, house wrens, and baby bunnies?

McGowan's answer involves "compensatory mortality." Briefly put, if the crows don't eat baby birds and other small animals, other predators will. That's why prey like robins and rabbits breed so rapidly: most of them will quickly become food. So long as the number eaten is within the limits of normal mortality, "exactly NOTHING happens to the overall population." McGowan summarizes: "Crows are NOT a problem to most songbird populations, especially not those that are likely to be found around people's houses. When crows move in, the other birds don't leave."

The difference between urban deer and crows is that our deer have no predators and hence quickly multiply. McGowan, who has studied crows for decades, says: "Most crows don't even live a year, having died in the egg or as nestlings."

The poetic term for a gathering of crows is "a murder of crows." But once I learned that the mess in my birdbaths was the result of normal food gathering and not "murder"-killing without justification or excuse-I decided to follow the lead of scientists and refer to the group as a flock. And to let the birdbaths stand dry for a week or so.     (end of article)

[Originally published in July, 2019.]

 

 
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