More than four million miles of roads connect almost 330 million people in the United States. Humans rely on these corridors to facilitate migration and enable the commerce that allows our species to thrive. Likewise, wildlife require corridors. Connected habitats enable migration, colonization, adequate nutrition, and the interbreeding necessary for wildlife survival.
Using advancements in GPS technology, scientists have developed a cornucopia of data surrounding wildlife corridors. For example, in 1998, biologists at the University of Wyoming used GPS collar data to identify a 100-mile long migration corridor for pronghorn leading from Grand Teton National Park to the Green River Basin. Along the journey, thousands of pronghorn and mule deer were forced to cross highway 191 near Pinedale, Wyoming. Vehicle collisions were common.
More than 140 mule deer and pronghorn were killed each year along a 27-mile stretch of this highway. Collision data and corridor research helped garner public support for building a series of wildlife overpasses and underpasses along this stretch of highway. These crossings, known as Trapper’s Point, facilitate the migration of thousands of pronghorn and mule deer annually. Vehicle collisions have declined by more than 70%, and this multi-millennia old wildlife corridor remains intact.
Other research highlights the consequences of failing to conserve corridors. Big horn sheep in Grand Teton National Park used to descend thousands of feet from the jagged spires of the range, to the valley floor in winter. However, human development in the first half of the 20th century cut off migration routes. The remaining, and declining herd now spends its entire life scraping out a living on the harsh peaks of the Teton Range.
Once these migration corridors are cut off, they are difficult to reestablish. In many species such as elk, pronghorn, mule deer or bighorn sheep, migration is a learned behavior—passed from mother to young. If the mother stops migrating, her offspring will not migrate. This can impact animal health and herd viability, and disrupt other natural systems. Limiting development in corridors is important.
We already impede many known migration routes. Highways, fences, oil and gas development, and new home construction are just a few of the barriers that block migration pathways. Yet, for every known wildlife corridor, there are many more undiscovered. Our ever expanding human footprint makes identifying and conserving wildlife corridors critical for maintaining biological diversity.
Wildlife holds intrinsic and economic value. It feeds millions of Americans each year, drives tourism in many places, and reminds us that wild places still exist. At a moral and legal level, identifying and conserving wildlife corridors are necessary to satisfy our trust obligation to both our wildlife resource and future generations. Wildlife corridors matter.