WASHINGTON (AP) -- Oh, deer! Unwary motorists aren't the only ones who need to beware of the four-legged bane of gardeners, especially at this time of the year. Pilots are also having deer encounters that rarely end well, especially for the deer.

Soaring deer populations are nuisances for airports and threats to pilots and planes, according to aviation and wildlife experts.

Whether driven by hunger or just crazy for love, deer will do seemingly anything to get onto airport grounds and runways, including leaping over tall fences or squeezing under them. Once there, they like to warm themselves by sauntering on runways, which hold heat longer than bare ground. But put a deer and a plane together on a runway and both can have a very bad day.

From 1990 to 2013, there were 1,088 collisions between planes and deer, elk, moose and caribou, according to a recent joint report by the Federal Aviation Administration and the Agriculture Department. Most of the planes suffered damage, and some were destroyed, the report said. One person was killed and 29 others injured. There's no mention of the fate of the deer.

The vast majority of collisions involved white-tailed deer, the smallest member of the North American deer family, but big enough to wreck a plane.

Their population has risen from about 350,000 in 1900 to more than 28 million in 2010. They've caused $44 million in aircraft damage and 238,000 hours of lost flying time over the past 24 years. About 30 percent of collisions occurred during the October-November mating season.

Last month in Florida, the propeller of a small plane landing at night at the Ormond Beach Municipal Airport struck a deer, causing the plane's front landing gear to collapse, according to local police. The pilot and three passengers were unhurt.

Most collisions involve small planes, but airliners occasionally tangle with deer as well. A US Airways jet plowed through a herd of deer shortly after landing at Charlotte Douglas International Airport in North Carolina in October 2010. At least one deer became entangled in the plane's main landing gear and the runway had to be closed for about 40 minutes while the mess was cleaned up.

Since the Sept. 11, 2001, terrorist attacks, many larger airports have built tall fences topped with barbed wire, mostly as a security measure but also to keep deer and other wildlife out, said Richard Dolbeer, an Agriculture Department science adviser and co-author of the report. Airports also use sharpshooters to eliminate deer that manage to make their way under fences or through cracks, he said.

"Just an 8-inch gap and they can squeeze through," Dolbeer said.

Smaller airports that serve mainly private pilots have been slower to install deer-proof fences, he said. So while deer collisions have dropped significantly at large airports, they're down only slightly at smaller ones. Last year, there were 33 collisions, he said.

The College Park Airport in Maryland is a smaller airport struggling to keep deer out. It is bordered on one side by a park and lake, and on the other by an industrial area. Nearly every day airport employees get into a truck, flip on the siren and charge toward deer into order to scatter them off the grounds so planes can take off or land.

A 7-foot fence was built a few years ago along the park border, but a beaver felled a tree onto the fence and allowed the deer back in. The airport then put up an 8-foot fence with barbed wire, but deer just walked around the airport to the industrial park and leapt over a 6-foot fence on that side. The airport now plans to build a taller fence there as well.

"Nature found a way," said Langston Majette, the airport's senior operations specialist.

Officials at the AAA automobile club's mid-Atlantic chapter were so impressed with the deer problem at airports that they decided to highlight it in their annual warning this week to motorists to beware of deer.

"It is the call of the wild," AAA spokesman John Townsend II said. "This time of year the problems that aircraft pilots face on runaways are similar to the ones that motorists encounter."

___

Online:

Wildlife Strikes to Civil Aircraft in the United States, 1990-2013: http://www.faa.gov/airports/airport_safety/wildlife/media/Wildlife-Strike-Report-1990-2013-USDA-FAA.pdf

___

Follow Joan Lowy on Twitter at https://www.twitter.com/AP_Joan_Lowy