They're crows, crows, and more crows.
Flocks of the great black birds have been observed at the Heights, where the sight of them roosting in inky clumps atop the leafless trees of College Road sometimes suggests a scene out of Hitchcock's "The Birds." They've also left copious mementos on campus sidewalks, roadways and other vulnerable surfaces.
Where have they all come from?
Boston College Environmental Studies Director Eric Strauss says an extended flock of as many as 700 crows from throughout the Boston area have made the University their gathering ground for the winter. Although the coming of spring has seen their numbers decrease - and an end to their evening caw-fests along College Road - don't think you've seen the last of them, Strauss says.
Crows are among the most social, as well as intelligent, of birds, and in winter months form large extended groups called "roosts" that serve as avian mutual-aid societies, said Strauss, who studies crow behavior at a field station the BC Environmental Studies Program maintains on Cape Cod.
The roosts serve as "information centers" for the finding of food and mates as well as protection during the winter months, according to Strauss, who said crows depart for independent territories as family groups in the spring and return to the larger formation in the fall.
One such roost at Shoppers World in Framingham grew to as many as 5,000 birds in size, said the naturalist, who noted the cutting of trees during development near the shopping center seems to have chased the birds away.
A number of those crows may now be calling Boston College their winter home. Strauss couldn't be happier: The biologist sees the seasonal influx of the birds to campus as a golden opportunity to study crows' social behavior and the ways in which they leave and re-form roosts over the course of the year.
"It's awesome - we watch them every day," said Strauss. "My students have been following [the roost] for weeks, and talking about it in our Animal Behavior class."
The crows started to appear in great numbers on the BC campus in October, and should be gone by the end of this month, when they will return to their home territories to nest, he said. Perhaps six family groups call the Chestnut Hill campus home year-round.
Crows have been increasing in number in eastern Massachusetts in recent decades, Strauss said, as decreased hunting and the reforestation of lands once cleared for farming have led to a return of such woodlands creatures as white-tailed deer, coyotes, foxes and bears to the suburbs.
Strauss said he finds crows particularly intriguing objects of study because of their complex intelligence: With individual life-spans of up to 30 years, crows maintain an "extraordinarily complicated" social system of extended family groups and have a distinct language encompassing some 35 different calls.
Crows are among the smartest of birds, and thus present unique challenges to the field naturalist, said Strauss, who described the lengths to which he has gone to camouflage his camera lenses lest sharp-eyed crows identify them as shotgun barrels. "They have their own sentries who are paying as much attention to you as you are to them," he said.
Crows and ravens have been feared over the centuries as macabre-seeming omens of doom or disliked as boisterous and crop-raiding nuisances, but Strauss said the crafty black birds are really quite fascinating.
"There isn't a more intelligent bird we could have near us," he said. "I would encourage folks to watch them a few minutes. You'd be compelled at the drama being played out in the trees."
Where biologists may welcome the feathered visitors, however, Buildings and Grounds workers may not. Linden Lane after a fly-over recalls, in places, one of the famed guano islands off the Chilean coast.
Of course, getting rid of several hundred crows would not be easy, Strauss said, as the birds are no Canada geese. They are not easily spooked by air cannons and they outright scoff at dogs. "You can watch them taunting dogs from the trees," he said. "They enjoy that."
So what to do with a surplus of crow guano? "It's useful in the garden, but not so useful on the top of your car or in your hair," Strauss said. "I always wear a hat."
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