By Joe Taschler

Wings and tails are crucial parts of most aircraft, but also can be major hazards when they happen to be made of feathers or fur.

Airplanes colliding with animals ranging from white-tailed deer to birds of every shape and size are a constant problem at airports across the United States, and federal aviation regulators are working to fully document the scope of the problem.

The issue is so important that Milwaukee's Mitchell International Airport has a full-time wildlife biologist on staff who works to prevent animals from making it onto the airport's property.

"He has to advise on types of vegetation that are not attractive to waterfowl or birds and types of plantings that do not offer good hiding places" for animals and birds, said Pat Rowev, an airport spokeswoman. Everything from grass planted along airport freeways to the location of storm water retention ponds has to be looked at in terms of the wildlife that it might attract, Rowe said.

It's not just major commercial airports like Mitchell that must deal with wildlife hazards.

In Watertown, the white-tailed deer problem at the airport has become so bad, a professional sharpshooter has been brought in to thin the herd in the area, said Jeff Baum, president and CEO of Wisconsin Aviation, which operates the airport.

"The sharpshooter, his first day out, got three of them," Baum said. "He's counted over 25 deer on the airport itself. It's just crazy. We see them every night."

The sharpshooter has been effective to the point that "we think we have the situation under control," Baum said.

Baum knows firsthand how dangerous the situation can be. A plane he was piloting several years ago struck a deer just after landing. No one on board was hurt, but the aircraft sustained $50,000 in damage.

"When you've got aircraft that are touching down at 120 to 140 mph at dusk, and a deer comes running out on the runway, you've got a real issue," he said.

Anyplace where there are airplanes, there are wildlife hazards.

"When it comes to deer and those types of animals, commercial service airports in the last 10 years have really beefed up their capabilities in controlling that," said Bob O'Brien, Executive Director of the Wisconsin Airport Management Association. in Blue River, Wis.

The most effective way to keep deer off airports is to build fences that are too tall for them to jump over, O'Brien said.

"Geese and birds, they are more challenging given that they have the ability to fly," in and out," O'Brien said.

The number of animal-aircraft collisions reported each year has increased sixfold to a record 11,315 in 2013 from 1,851 in 1990, according to a study done by the Federal Aviation Administration and U.S. Department of Agriculture. Birds were involved in 97 percent of the reported wildlife strikes while land-dwelling mammals were involved in 2.2 percent of cases.

Growing wildlife populations, more aircraft and a sharper focus on reporting of planes colliding with animals are contributing to the higher numbers.

Some of the encounters are minor. Others are terrifying. US Airways Flight 1549 had to ditch into the Hudson River off New York City in January 2009 after Canada geese were sucked into both engines on the Airbus A320, causing an almost total loss of thrust, according the National Transportation Safety Board. Five people were seriously injured.

Many populations of large bird and mammal species that are often involved in aircraft mishaps have adapted to living in urban environments, including airports, according to the FAA/USDA report.

"The wildlife figure out really quickly that (airports) are great refuges where no one is hunting them, nobody is bothering them," Baum said. There are a lot more potentially problem critters to deal with these days.

The resident (nonmigratory) Canada goose population in the U.S. and Canada increased from about 500,000 to 3.8 million from 1980 to 2013, according to the FAA/USDA report.

The white-tailed deer population increased from a low of about 350,000 in 1900 to about 15 million in 1984 and to over 28 million by 2010, the report said.

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