Human Development Threatens Ancient Paths

by Meredith Taylor

The length of pronghorn migration exceeds even the movements of African elephants and zebras and approaches those of Asian chiru antelope. Photo by LuRay Parker/Wyoming Game & Fish Dept.

Each fall since the last Ice Age, biggame animals have followed ancient migration paths from the summer ranges of Yellowstone's high country south through the Gros Ventre, Snake, Hoback and Green River drainages and on to the Upper Green River Valley and the Red Desert, where they spend the winter. (See articles in the past three issues of Frontline.) Predators followed their prey in this annual passage, and a wide range of amphibians, insects, reptiles, birds and mammals also take part in this dance, part of nature's delicate balancing act.

Long Distance Migration (LDM) is now considered by conservation biologists as perhaps the most dramatic yet endangered phenomena on Earth. Wildlife biologists and managers understand why animals migrate, but few have offered a vision with specific strategies to sustain the world's remnant migration corridors.

According to a recent study by Joel Berger of the Wildlife Conservation Society (WCS), development threats to the Upper Green River Valley are particularly noteworthy. Berger's study focused on 29 terrestrial mammals in more than 100 locations on five continents, and reported that few remaining LDMs have a rosy long-term prognosis if current land-management patterns continue.

During the past century, some private organizations and governments have incrementally acquired and managed whole migration corridors to protect and connect wildlife habitat. But many more big-game travel routes have been converted to human uses, displacing wildlife forever.

Berger found that in areas of the western hemisphere with low human impacts, five species - bison, elk, moose, deer and pronghorn - continue to follow ancient migration routes. Although the Greater Yellowstone Ecosystem has lost almost 75% of its historic migration paths for bison, elk and pronghorn, Berger notes that the GYE's pronghorn still travel up to 160 miles each fall and spring. Their journey is longer than that traveled by African elephants and zebras and approaches that of Asian chiru antelope and African wildebeests.

Unfortunately, unprecedented levels of energy and subdivision development in the GYE may block this important pronghorn LDM.

One landscape-scale protection proposal comes from WCS, which advocates the designation of a National Migration Corridor to provide long-term safeguards for a multitude of migratory species in the GYE. In addition, WOC's Restoring Wild Patterns program proposes acquiring important migration-route land parcels through conservation easements, land use plans and government conservation funds.

Wyoming has a proud history of farsighted habitat protections, including the creation of Yellowstone (the world's first national park), the Shoshone Forest Reserve (the nation's first national forest) and Devil's Tower (the nation's first national monument).

It's time to revive that visionary spirit, using sophisticated modern tools to assure that the GYE's ancient migration paths remain long after the region's last fossil fuels have been extracted.