Bears Need Highway Overpasses, Too | Emily Badger | Aug. 12, 2013 | The Atlantic Cities
Who speaks for the bears? Sometimes scientists do. How does a bear cross the road in Canada? Emily Badger writes:
Beautiful Banff National Park in Canada began to install the first of several dozen underpasses and overpasses across the Trans-Canada Highway inside the preserve’s boundaries in the 1980s. They connect on either side of the four-lane road to no sidewalks or trails. [….]
The park originally installed the crossings to protect motorists. A thousand-pound elk can wreck your car. On one 15-kilometer stretch of the highway, there used to be an average of a hundred elk-vehicle collisions every year. “I think the park realized sooner of later, they’d have a human fatality in some of these accidents,” Clevenger says, “and they were going to be taken to court.”
But over the years, critics and transportation planners, even some environmentalists have groused about the idea: Taxpayer money, building overpasses for bears? Is that really necessary? Would they even use the things? Researchers have been methodically studying the crossings since 1996 to answer this. And it turns out that, yes, animals deterred by fencing that now runs the full 70-kilometer length of the highway in the park actually cross the road an awful lot like a rational pedestrian would. It takes them a while, though, to adapt to the crossings after a new one is constructed: about four to five years for elk and deer, five to seven years for the large carnivores. [….]
To put this notion to rest, Clevenger and colleagues with Montana State University’s Western Transportation Institute recently concluded a three-year study of the DNA from 10,000 hair samples of bears non-invasively snagged from the crossings and other areas around the park (the collection technology is not very sophisticated: this requires a little piece of barbed wire). DNA from bear hair is pretty amazing. It can reveal not just the difference between a black bear and a grizzly, but the identity of the individual bear, its gender, its relationship to bears of the same family.
he study found that about 20 percent of the bears in the geographically broad sample population were using the crossings, and with the same activity patterns they exhibit in the back country. These bears were not, for instance, making a run for it in the middle of the night when traffic volumes were low. And all of this means that this infrastructure is doing much more than protecting motorists. It has enabled the free flow of mama bears and bear genes across four lanes of high-speed traffic.
Via Bears Need Highway Overpasses, Too | Emily Badger | Aug. 12, 2013 | The Atlantic Cities at http://www.theatlanticcities.com/commute/2013/08/inside-dramatic-world-transportation-planning-bears/6487/.