Airports work to increase safety

But inside the fence are large swaths of open fields occupied by rodents that are food for predatory birds like hawks and vultures. Both species are considered soaring birds, attracted to the thermal heat patterns created by long stretches of hot pavement.

Mitigating the potential damage requires year-round vigilance by airport staff trained to carry out an integrated wildlife plan -- a series of escalating steps designed to minimize encounters between animal and aircraft.

Those steps range from sound-emitting "bird bangers" to netting that covers roofs where birds like to roost. It also includes covering trash bins to eliminate them as food sources, and using native grasses rather than flowering bushes and trees that produce berries and seeds that animals like to feed on.

The absence of colorful landscaping has prompted complaints at some airports in Indiana where the USDA biologists are working.