A federal aviation expert put it more bluntly: "It's definitely a real hazard."
In many instances, said the official, who was not authorized to speak publicly on the subject, aircraft from the era when hitting big birds was a rarity were not built to sustain those impacts.
"The threat to big airplanes is jet engine outages," he said. "The threat to smaller planes and helicopters is even greater."
Five people died in 2008 when the wing of a small passenger jet struck a pelican near Oklahoma City. Eight people died in 2009 when a red-tailed hawk crashed through the windshield of a helicopter carrying passengers to an offshore oil platform in the Gulf of Mexico. A red-tailed hawk also was blamed for the crash last year in California of a Marine AH-1 attack helicopter that killed two Marines.
The USDA, working on behalf of the FAA, has done a variety of creative things to reduce airport wildlife. At Dulles International Airport, for example, fences extend two feet underground to foil small animals. At Baltimore-Washington International Marshall Airport, the wildlife service traps and relocates American kestrels, which are a type of falcon.
Signs and trees where birds like to perch have been reduced in number, and a sticky coating that birds find unpleasant has been applied in some places. Standing water has been reduced or eliminated. Netting covers light posts and hangar corners to discourage nesting.
Dumpsters that draw rats and the raptors that feed on them have been minimized.
"Not providing the food, water and shelter that the animals want chases more than 90 percent of them away," Bannerman said.
When that fails, airports such as BWI use the noise of cannons to frighten them. And sometimes, Bannerman said, they are "lethally removed."
She said most bird strikes occur between July and October, and they peak in late summer "because you have all of the fledgling new birds."
The first known bird strike by an airplane occurred in 1905 above an Ohio cornfield. It was dutifully recorded in a diary by the pilot, Orville Wright.