Dead animals on the highway are a fact of life in California and many people think there is nothing that can be done about it. But now wildlife biologists and transportation engineers are realizing there is actually a lot that can be done.
One of the most successful strategies in recent years has been to create wildlife crossings that allow animals to go under or over busy roads. These are manmade structures being built in a wide variety of ways for a wide variety of animals around the world. Interest in the idea is exploding because scientists report the crossings are working, if they are done correctly.
"Studies have shown that well-placed wildlife crossings, coupled with fencing, can reduce wildlife-vehicle collisions by as much as 75 to 100 percent," said U.S. Forest Service biologist Sandra Jacobson.
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Jacobson is part of the Highway 89 Stewardship Team, a coalition of groups, experimenting with wildlife crossings near Truckee in the high Sierra. The first crossing was a tunnel under the highway, built seven years ago. Pictures from motion activated cameras show animals are passing through it, and there is additional evidence of use in thousands of animal tracks in the dirt at the bottom of the tunnel.
But Jacobson says there is still a lot to learn about the best way to get animals to use crossings. So now the Stewardship Team is building two more tunnels in a first of its kind experiment.
The tunnels will be as identical as possible, a mile apart from each other, in an area known to be full of wildlife. Fences along the road will help guide the animals to the crossings. Jacobson says the challenge is "trying to get the entrances of the structures to where animals will just basically find a trail to walk in."
Having two tunnels will allow researchers to try different strategies in each and see what works best. They plan to experiment with ideas, such as sound barriers to reduce traffic noise that may scare the animals. Jacobson says they may also try making one tunnel look more natural. "We can put rocks and boulders and stumps inside of the structure and maybe that will make them feel more comfortable," Jacobson said.
Caltrans is a key partner in the projects and is also trying a variety of animal crossings in other areas. "As the data comes in, as we show the pictures, as people evaluate them, we are able to show that they are working, better than we ever expected," said Caltrans biologist Suzy Melim.
Caltrans is spending $2 million the experimental tunnels, hoping the research will lead to even better and cheaper solutions.
Researchers from around the world are eager to see what happens, and they are sharing their own experiences with wildlife crossings, as well as other animal road strategies. Road and wildlife experts from across the United States and four countries are attending a weeklong class on the emerging science of "road ecology." It's all happening at a research station run by the University of California, Berkeley in the Sagehen Forest near Truckee.
Some of the students in the class are from a wildlife conservation group called Panthera. They came all the way from South America to find out more about how to save jaguars from being hit by cars.
"Roads enable hunters, loggers, and other humans to occupy (the jaguar habitat) and that becomes a barrier to animals," according to Panthera Regional Director Esteban Payan. He said his team is at the workshop because " he wants "to learn from the best."
The goal is to keep animals safely off the roads, but make sure they can still get across to access the habitat they need to survive.
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Written and produced by Jennifer Olney.
CA researchers keep animals, people safe on the highway