Deer dwindle near gas wells

One of the Rocky Mountain region's most extensive mule deer populations may be threatened by increased natural gas development as the search for new energy sources intensifies, according to a study released this week.

The findings from Western EcoSystems Technology Inc., based in Cheyenne, Wyo., said that the winter mule deer population in western Wyoming's Pinedale Mesa dropped to 2,818 in 2005 from 5,228 in 2002, a 46 percent decline.

"Results to date suggest that winter habitat selection and distribution patterns of mule deer have been affected by (natural gas) well pad development," the study said. "Changes in habitat selection by mule deer appeared to be immediate."

The nearly 100-square-mile mesa is a unique winter range for wildlife, providing a home to 4,000 to 6,000 mule deer.

The mesa also is the site of one of the nation's biggest natural gas plays, with dozens of drilling rigs and hundreds of producing natural gas wells.

Locked deep within tight sandstone deposits, an estimated 40 trillion cubic feet of natural gas lies below the mesa's surface. That's enough gas to satisfy residential demand for Wasatch Front cities for more than 300 years, or the nation's needs for two years, according to Ronald Hogan, general manager of the Pinedale Division for Questar Market Resources.

The WEST Inc. study — paid for by Questar Exploration and Production Co., a subsidiary of Salt Lake-based Questar Corp. — monitored deer over a four-year period by using a GPS radio-collared tracking system.

A separate nearby winter range for mule deer, with no oil or natural gas production, also was monitored as a control group. It showed no declines in mule deer population over the same four-year period.

In fact, the control area saw its mule deer population increase to 4,281 in 2005, up from 4,050 in 2002.

Four parameters were addressed in the study, which included monitoring of adult doe survival, over-winter fawn survival, reproduction and abundance. Survival rates for adult female deer and fawns were slightly lower on the mesa compared to the control area.

Because the survival rates were approximately the same in both areas, Hogan said the deer wintering on the mesa could be emigrating to other areas.