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Wildlife Bridges

June 17, 2019 By EarthWise Leave a Comment

Highway accidents involving animals are a big problem for both people and animals.  About 200 people die every year in the U.S. as a result of collisions with animals.  In total, one to two million large animals are killed by motorists every year.  And these crashes are expensive:  deer-car collisions cost an average of more than $8,000 each; elk-vehicle collisions about $25,000; and moose-vehicle collisions over $44,000. 

In the United States, there are 21 threatened and endangered species whose very survival is threatened by road mortalities.   These include Key deer in Florida, bighorn sheep in California, and red-bellied turtles in Alabama.

One solution that has been quite effective around the world in reducing car-animal collisions is wildlife overpasses and underpasses.  Crossings and fencing that guide animals over or under highways reduce collisions by 85-95%.

These traffic-spanning bridges and tunnels have been popular in Europe since the 1950s.  The overpasses usually look much like regular overpasses for cars but are decked out with native flora.  The underpasses, which assist shyer and smaller animals, are typically invisible to drivers.

Washington State has recently started building wildlife bridges and underpasses on Interstate 90.  These passes will allow elk, black bears, mountain lions, pika, and even trout to traverse what was once a near-impenetrable barrier of road.

Some animals that are accustomed to human structures start using the crossings almost immediately.  For others, there is learning curve.  As in many things, the early adapters are important as they provide paths and model behavior that more reticent animals learn to follow.

Wildlife bridges are a very good thing for wildlife and for people.

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Web Links

How wildlife bridges over highways make animals—and people—safer

Photo, posted July 22, 2017, courtesy of David Fulmer via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Wildlife And The Border Wall

February 14, 2019 By EarthWise Leave a Comment

The border between the United States and Mexico is nearly 2,000 miles long, stretching from San Ysidro, California to Brownsville, Texas.  Discontinuous barriers currently cover approximately 650 miles of our southern border. As the particulars of how to better secure the remaining 1,350 miles of border are worked out, one thing is abundantly clear: extending physical barriers would negatively impact wildlife and the environment.

The Trump Administration has called for a 1,000-mile wall, which would cut across land that includes important habitats for wildlife.  According to an article signed by nearly 3,000 scientists, this plan would “threaten some of the continent’s most biologically diverse regions” by inhibiting species movement and triggering flooding. The paper, which was published in the journal Bioscience, highlights how more than 1,500 native animal and plant species would be affected by the wall, including 62 that are listed as endangered or vulnerable.

An extended border wall would not only impede movement of many wildlife species but it would also put pressure on creatures already in peril, such as the Mexican gray wolf and the Sonoran pronghorn.  Other at risk animals include the ocelot, black bear, and desert bighorn sheep. 

According to researchers, extending the border wall could cause problems for low-flying birds and insects. Even plants, including the endangered wildflower Zapata bladderpod and the threatened whiskerbush cactus, are particularly at risk.

According to a 2011 study, bird-watching and other forms of ecotourism in the Lower Rio Grande Valley brought in more than $344 million in economic activity and approximately 4,400 jobs. 

Preserving our natural heritage must be part of this national security discussion. 

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Web Links

Nature Divided, Scientists United: US–Mexico Border Wall Threatens Biodiversity and Binational Conservation

Photo, posted December 14, 2014, courtesy of Tony Webster via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

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