In February 2007, two planes headed for Chicago’s O’Hare International Airport diverted their landings at the last minute. The reason: There were coyotes on the runway.
Just as coyotes have become increasingly comfortable onto the streets of American cities such as Chicago, they’ve also pushed their way onto the tarmacs of airports around the country. They’re the most common carnivore to be found causing trouble for air traffic, researchers report in the May Transportation Research Part D: Transport and Environment.
Carnivores are actually only a small threat to planes. Birds are, by far, the biggest danger. And when it comes to mammals, deer have caused almost as many reported incidents with U.S. aircraft as all carnivores combined. But as the incident in Chicago shows, coyotes and other carnivores can still cause airport delays or, worse, damage planes.
In the new study, Alexander Crain of Mississippi State University and colleagues pulled information from the Federal Aviation Administration’s National Wildlife Strike Database about airport incidents from 1990 to 2012 that involved carnivores. (The database is online — you can play around with it and find out which species are most likely to cause trouble at your local airport.) They found 1,016 incidents that occurred as U.S. civil aircraft of any size were taxiing, taking off and landing, with each phase counting as one plane movement.
Coyotes accounted for the most incidents (404), followed by striped skunks (207) and red foxes (120). One incident involved an American black bear (unfortunately, there are no details of what happened in that one). Most often these wildlife encounters resulted in little to no damage, but 12 accounts reported “substantial” damage, and in two the plane was reported as “destroyed.” Those two categories drove up repair costs to more than $7 million in total.
One interesting trend in the study was that reports increased from 1990 to 2012, when the rate of reported incidents was about 1 per million plane movements. Airports could be having more wildlife encounters, or, because adding a report to the database is voluntary, people simply may be reporting the incidents more regularly. That may be likely, the researchers say, since public awareness of the dangers that wildlife can pose to aircraft rose significantly after an incident with a goose sent U.S. Airways Flight 1549 into the Hudson River in January 2009.
Incidents rose at night and between July and November, and animal behavior might explain that. Many species are more active at night. And juvenile coyotes disperse from their mothers starting in October.
Better fences may help keep carnivores out of airports, the researchers note. Better night lighting or thermal cameras may help pilots spot potentially dangerous wildlife at night. And because there are no conservation concerns for any of these animals, predator control programs could help (though such activities are often criticized by the public).
A couple years ago, O’Hare tackled another one of the scientists’ recommendations — eliminating young vegetation, a habitat type that coyotes seem to prefer (the airport used burros, llamas, goats and sheep). But the researchers warn that manipulating airport vegetation should be done carefully. Those alterations, they say, could simply make the airport more suitable to other potentially dangerous wildlife.