WASHINGTON -- For all of America's vigilance against terrorists, danger does not always come on two legs.
The threat posed by beavers, woodchucks, deer, blackbirds and other seemingly benign critters has come under federal investigation.
A study ordered by Congress amounts to a compendium of dangers from the feathered, the four-legged and the no-legged:
* 27,000 injuries a year from rodents.
* $1 billion in damage a year from cars hitting deer.
* 15 deaths a year from snake bites.
* 6,000 collisions between birds and airplanes in 2000. Starlings are known as "feathered bullets" because they can cause so much trouble.
* $70 million in annual livestock losses from predators, mainly coyotes.
* Odd incidents of planes being damaged by wingless creatures, including turtles, alligators, foxes and woodchucks that apparently lumbered or skittered onto rural airstrips.
The General Accounting Office, Congress' investigative arm, studied problems caused by wildlife and the effectiveness of federal actions to protect people, their property and businesses from them.
It was asked to do so by members of Congress involved in approving the budget of the Agriculture Department, which kills some predators and tries to shoo others away.
The study found that nonlethal means of scaring off wildlife show promise, but many animals learn to thwart the best-laid plans.
For example, lamb carcasses were laced with a chemical to make coyotes throw up, in the hope they would steer clear of lambs.
The wily coyotes stopped eating them. But they kept killing them.
Llamas and lasers may be more promising.
Ranchers have discovered that llamas bond with sheep. They will chase coyotes, gather sheep and stand between the two with little or no training. "Guard llamas" also stay on the job longer than guard dogs.
Predators and pesky birds often adapt to loud noise and flashing lights, while rattled people in the area don't.
But the study says harmless lasers have effectively scattered birds that interfered with the search for evidence in World Trade Center debris at a landfill.
Researchers gave a nod to the large if unspecified economic benefits of wildlife, but it proved easier to quantify losses.
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