Birds and aircraft: fighting for airspace in crowded skies

Birds and other wildlife such as deer (Odocoileus spp.) pose increasing economic and safety concerns to aviation interests in the USA. Civil aircraft collisions with wildlife (wildlife strikes) annually reported to the Federal Aviation Administration (FAA) increased from about 1,700 in 1990 to 4,500 in 1999. Waterfowl (Anatidae), gulls (Larus spp.), raptors (Accipitridae, Pandionidae, Cathartidae, Falconidae) and deer were involved in 80% of the reported strikes in which aircraft were damaged. Wildlife strikes caused annual losses of $300 million to civil aviation, 1990 to 1998. The known number of civil aircraft destroyed as a result of wildlife strikes in the USA increased from four in the 1960s to 22 in the 1990s. The number of airports requesting assistance from the U.S. Department of Agriculture’s Wildlife Services program increased from about 42 in 1990 to 363 in 1999. Attendance at annual Bird Strike Committee USA meetings increased from 10 people in 1990 to over 300 in 1998-1999. Four factors have synergistically interacted to increase the problem of, and interest in wildlife strikes in the past 20 years. First, populations of many species hazardous to aviation have increased and adapted to urban environments such as airports. Second, passenger enplanements and commercial air traffic (landings and takeoffs) have increased at annual rates of about 4.2% and 2.6%, respectively, from 1980 to 1998. Third, modern two-engine turbojet and turbofan aircraft are generally less apparent to birds because these aircraft are faster and quieter than older aircraft. Finally, liability issues related to wildlife strikes are increasing for airport operators and others. The National Transportation Safety Board issued nine recommendations to the FAA in November 1999 that, if implemented, should reduce the threat of wildlife strikes. These recommendations included more research in methods of repelling birds from airports, use of radar to warn pilots of bird concentrations, development of wildlife hazard management plans for airports, mandatory bird strike reporting with better identification of species which are struck, and improved interagency cooperation in issues involving aviation and wildlife