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A Pilot Geographical Information Systems (GIS) Assessment of Rocky Mountain Bighorn Sheep Habitat in and Around Great Basin National Park, Nevada

Great Basin NP
Neal Darby
Bighorn sheep are getting help from high technology, including GIS, as
wildlife biologists try to prevent a symbol of the West from vanishing from
Great Basin National Park in Nevada. Today, fewer than a dozen Rocky
Mountain bighorn remain in the rugged Snake Range in and around the park,
where hundreds of the majestic creatures once roamed. Early on, wildlife
biologists tried to bolster the herd by adding bighorn sheep from other
areas. Those efforts failed, and the herd continued to dwindle even after
the creation of the national park in 1986.

In 2001, wildlife biologists used GIS technology to see if the loss of sheep habitat played a role in the herd's woes. Using a GIS software program called ArcView developed by ESRI, researchers evaluated whether the herd had enough room to survive and grow.

The resulting GIS map showed the sheep still had plenty of habitat in
general but barely enough room to bear and raise their young. Bighorn ewes
and their newborn need areas with plenty of grass and water during the
spring lambing season. They also need open areas where they can spot
mountain lions and other predators and escape pursuit over rocky slopes.
The GIS map shows these to be in short supply for bighorn lambs. One
GIS map layer identified the southerly, steep slopes where the snows melt
early and provide grasses for forage. Another map layer showed the
availability of water, and a third identified types of vegetation that
indicate open areas and protection from predators. From this information,
wildlife biologists and fire managers are further using GIS to plan
remedies, such as prescribed burns and thinning of forests, to restore
suitable lambing areas in hopes that the herd will one day thrive again in
its historic range.

April 08, 2004