04/12/2006
Betty and Other Crows
Last Friday, I was flipping rapidly through the TV channels looking for an alternative to the day’s depressing news when I stumbled upon Animal Planet. I was surprised to see a crow with a wire in her beak. Sure enough, it was Betty! You remember Betty – she was the crow I mentioned two weeks ago and in an earlier column. Betty is celebrated as the crow that, faced with a delicacy at the bottom of a narrow glass tube, picked up a length of wire and fashioned a hook with which she retrieved the food item. The Animal Planet segment showed Betty doing her thing. A tiny bucket with a handle contained the food item; the bucket was at the bottom of a glass tube. Betty picked up the wire and bent it. Holding the wire in her beak and bracing herself with her foot on the top of the tube, she lowered the wire into the tube and pulled out the bucket. Betty did indeed know how to fashion and use a tool to accomplish an objective – one smart crow.
I took the coincidental sighting of Betty as a sign that I should revisit the subject of crows. Actually, I had decided that last week but got so wound up with the merger of Lucent and Alcatel that I had no space left to do justice to the crow. You may remember that two weeks ago I mentioned that Kevin McGowan, an ornithologist at Cornell University, had observed that a crow widowed by the West Nile virus had taken her brood and moved back in with her parents. After posting that column I was having a cup of tea in our breakfast room when I heard the distinct “caw-caw” of a crow in our backyard. This set me to wondering how McGowan could possibly have been able to determine that a widowed crow moved back with her parents. So I visited the Cornell Web site and found a plethora of information about crows that McGowan has assembled.
The answer to my immediate question about the widow was clear when I found that McGowan and his students have been following the American crow population in an area near Ithaca, New York since 1989. They’ve been climbing trees, some 10 stories high, and tagging young crows in their nests with different colored and numbered tags. The tags allow the researchers to follow the birds from the ground with high- powered binoculars and over the years they’ve followed the habits and movements of individual crows and families. McGowan now has records on over 350 crow families.
Crows are not only intelligent but they are also family oriented in ways unlike most other birds. Most birds feed their young up to the point where the youngsters are ready to leave the nest and fly. The parents encourage the young ones to leave the nest, although I’ve observed in our backyard that some robin parents still dig out worms to feed to their young on the ground after the latter have left the nest. Soon, however, the young ones take off or are chased away by their parents and that’s the end of the family ties. Crows, however, may preserve those family ties for years.
McGowan has seen crows that hang around for even 5 or 6 years and help to feed and raise their younger brothers and sisters. He’s seen as many as five birds on one nest feeding the nestlings. The older children may also help out by feeding their mother sitting on her eggs prior to hatching another brood. The average brood is three babies with the chances being that two will survive until the next year. This means the family can grow and McGowan has found that extended crow families of 15 or so are not uncommon. The older offspring also help out by defending the family territory and the nest. When a crow finally strikes out on its own, it may end up with a nest only a couple hundred feet from its parents’ nest. Close enough that a widowed crow can move back with her parents and be tracked by dedicated researchers.
Crows share the tendency of many other birds to sleep in “roosts”. For crows, the roost is typically a fall and winter thing; during the breeding season they tend to sleep in their own territories. I was shocked to find that the sizes of crow roosts commonly involve thousands or tens of thousands of crows and that some exceptionally large roosts may contain hundreds of thousands of the birds. One roost in Oklahoma was estimated by the State of Oklahoma Upland Game Inventory to number over two million crows! Obviously, one tree couldn’t hold a million crows; a roost may range in size from a single tree to a wide area of trees and/shrubbery depending on the number of birds in the roost.
Why do crows and other birds form roosts? Apparently, nobody knows the answer. Speculations range from the crows seeking protection from predators by sleeping in large numbers to the idea that the birds share or seek information about good foraging sites or even roost in or near good food sites. Near a good food site, they can have a hearty breakfast before going off to forage for a wider variety of foodstuffs. Typically, near the end of the day, the crows don’t just head for the roosting site but an hour or two before roosting will gather together in noisy groups, where they chase each other and fight or just make a lot of noise chattering. These groups then head for the roost where things usually quiet down for the night.
In the past, crows generally roosted in rural settings outside of town but today it is common to have roosting crows in the towns or cities. In urban settings, it seems that the crows prefer roosting in areas that are well lit at night instead of the darker sections of town. The move to the cities may illustrate the intelligence of the crows, which may have figured out that people in cities don’t usually have guns to shoot them and/or that there aren’t as many Great Horned Owls in the city. The owl likes to dine on crows if given the opportunity. By choosing well-lit areas for their roosts, the crows can see any predators more clearly.
McGowan has observed that in roosts in the darker country settings the crows settle and quiet down rather quickly. In the well-lit city roosts, there is more noise and birds will flit from one tree to another more often, unconcerned about unseen predators. Another possible advantage to city roosting is the fact that it is warmer in cities than the surrounding countryside, sometimes as much as 5-10 degrees Fahrenheit.
Crows have a tough time starting out, most not even living a year, either dying in the egg or as nestlings. However, once they’ve survived the first year, the outlook is much better. McGowan’s American crows average around three years for the females and about five years for the males before they start breeding. A real Methuselah was a 29 year-old American crow, the oldest known wild American crow. The second oldest known was just shy of 15 years old, so the record holder was probably quite exceptional.
McGowan also has had the opportunity to check out the old adage “to eat crow”. If you’re humiliated by having to admit a mistake, the expression implies that you won’t find the taste of crow to your liking. McGowan has had crow on several occasions and found it to be “just fine”, its dark meat comparable to wild duck. I would suggest, however, that you not try to bag a crow for your own tasting without checking the hunting laws in your locale. Discharging firearms in an urban setting is generally not looked upon with favor!
Allen F. Bortrum
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