Donna
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« on: 26-Oct-10, 07:38:33 AM » |
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from the Chicago Tribune
Crows, those winged icons of Halloween, are so smart … it's scary!
With Halloween upon us, we thought we'd explore one of the holiday's iconic symbols. But which one? Jack-o'-lanterns? Candy corn? Halloween couture? All as boring as boring can be.
What about crows?
They have been intertwined with mankind for thousands of years. They exhibit humanlike characteristics: They play, communicate and have the capacity to deceive. They're smarter than any cat and most children. (We acknowledge that your cat or child is exceptional and would regularly outperform crows, but our money would generally be on the bird.)
Despite their charms, crows have been maligned for centuries.
"There are a couple of reasons for this," says Kevin J. McGowan, an ornithologist working at the Cornell Laboratory of Ornithology in Ithaca, N.Y., who has studied crows for 25 years. "One is that they're black, and in our western European ethos, that's bad. They also got associated with carrion and death because in Europe there are no vultures. So somebody died, lying on the side of the road or after a battle, and the crows and ravens came in and picked at stuff because there it was, free food."
Closer to home and not as revolting, they get a bad rap from gardeners. It's undeserved, says John Marzluff, professor of wildlife science at the University of Washington and author of "In the Company of Crows and Ravens" ( Yale University Press, $19.95).
Marzluff says crows do more good than harm in a garden.
"They eat a great variety of crop pest insects (cutworms, army worms, even small bunnies)," he said via e-mail. "They do seem to have a penchant for pulling up some plants that are sprouting, famously corn. They also eat fruits and nuts, which can be a problem in orchards. But in the family garden they are good natural insecticide."
So crows are to be celebrated, particularly this time of year.
Here are more reasons they are cool:
A group of crows is called a "murder," a designation thought to date to the 15th century. The term is more literary or romantic than scientific. When crow experts talk shop, they usually refer to a flock, pair or family group of crows.
Speaking of "murder," crows have been known to kill one of their numbers in what seems to be a ritual of sorts. Marzluff said that there are many documented cases of this behavior. He has even seen it himself. "When I came upon this, the victim was injured already," he wrote. "It had a broken wing that might have been caused by a car collision or was inflicted by the group. Either way, the group was finishing off this bird. I suspect this happens when one bird is caught trespassing in another's territory, perhaps to sneak a copulation with a member of another pair (crows pair for life, but they fool around a bit)."
Most male crows live to age 10, females to 8, not a bad life span in the bird world, where a year or two is the norm. Three male crows that McGowan banded in 1993 are going strong at age 17 and could live to 20, he says. The oldest known captive crow was 57 when it died.
They have strong family values. McGowan equates it with our society, saying crows come closer to man than any other species studied, including primates. Crow society is family-based, he said. There's a single breeding pair that has offspring that don't leave right away and help raise the next batch of offspring, just like people. Relationships are maintained and individuals can join up with each other years later. Like us, crows have territories and they gather in communal places. When you see a number of crows gathering, he said, "those aren't gangs of crows, they're typically family groups that are helping each other make a living."
Crows can pick a particular person out of a crowd, probably more accurately than you can. Marzluff suspected as much and tried an experiment. Four years ago, he and his crew captured seven birds for banding — a slightly traumatic experience for the birds — and they wore caveman masks as they did it. He and a number of volunteers, some with caveman masks, some without, then walked around the UW campus, among the 40,000 students. Everyone who wore a mask was subjected to crow harassment — scolding, being dive-bombed, being followed. The birds knew the mask was evil. The thing is, most of the angry crows had never been touched by him or his crew. They learned by observation that the caveman was dangerous.
"This 'social learning' is an example of a high cognitive skill that is found only among the most intelligent and social of species (humans, whales and dolphins, other primates)," he wrote. "We have since determined that crows can learn to recognize a dangerous face by direct experience, by observation of a direct experience (seeing us capture another crow) and by observation of a tutor modeling behavior (seeing another crow scold a dangerous person). We have confirmed all this with less striking, much more realistic human face masks, as well."
A crow's vocabulary is extensive, with 30 or so unique calls, each with a distinct meaning. Each call is also shaded to indicate the intensity of a situation, and each has an individual signature unique to that bird. That way, crows can distinguish between family members, mates, neighbors and strangers. "This is important so they can react differently to different individuals," Marzluff wrote. "Reacting to a mate in distress is more important from an evolutionary perspective than reacting to a stranger, for example."
Juvenile crows like to play. "They chase each other around, pull each other's tails. They get an object like a leaf or a feather and they chase each other around, trying to get the object. Then whoever gets it gets chased," McGowan says.
There are several scientific studies that document tool use by crows. The best tool user is the New Caledonia crow, which makes tools from plant materials to probe into crevices for insects. In captivity, these crows will bend a piece of wire to make a hook, then use it to pull a bucket of food closer.
Crows seem to express emotions, something Marzluff and co-author Tony Angell are examining in their next book, "Gift of the Crow" (Simon and Schuster, due out in 2012). "Crows are very intelligent, among the most intelligent of all animals," Marzluff wrote. "They live a long time and they live in social settings where expressing emotions is an important part of life. They clearly let others know when they are meek, aggressive, fearful, playful and deceptive. The fact that they look you in the eye, crouch, erect their feathers and the like, using postures and positions much like a dog, makes reading their emotions tractable."
Some crow emotions and behaviors are amazing, such as leaving goodies — candy, pieces of bracelets, keys or shiny glass — for people who feed them, or pooping on the cars of people who harass them.
Scarecrows are a waste of straw. They have evolved from being built into fish drying racks by Native Americans to the kids ("crow boys") who chased the crows from European fields to the kites and concussive cannons of today. The crows get accustomed to each new idea, and man has to escalate the war.
(I watched the Crows on the Nature channel last night. They are the most amazing birds.) SMART!!!
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