University
of Wyoming Study Shows Major Impacts of Energy Development on Sage Grouse
A study funded by the oil and gas industry,
the Bureau of Land Management and the Wyoming Game and Fish Department
shows that natural gas development is affecting population size, nest
selection, and distribution of greater
sage-grouse in western Wyoming. The study by University of Wyoming
doctoral student Matt Holloran was conducted in the Pinedale Anticline
and Jonah development fields, huge sagebrush basins slated for coalbed
methane development in western Wyoming. Holloran also studied sage grouse
opulations in adjacent areas that are not subjected to CBM development
as his study control group.
The study's findings are remarkable and confirm what wildlife scientists
have stated for decades -- as conducted today, oil and gas development
is not compatible with sage grouse conservation. The findings should have
far-reaching impacts on how energy resources are developed on public and
private lands in Wyoming, Montana, Colorado and Utah.
The study found:
- Populations of breeding males on leks (sage grouse mating sites) in areas subjected to full-field natural gas development in the Pinedale Anticline and Jonah fields declined by an average of 51 percent from the year prior to development to 2004, compared to only a 3 percent decline at undisturbed leks.
- Males at three leks surrounded by natural gas development declined by 89 percent; two of the three leks were abandoned entirely within 3 to 4 years of initiation of gas drilling.
- Active drilling within 3.1 miles of a sage grouse lek reduced the number of breeding males that used the lek.
- As road traffic increased, the number of breeding males on affected leks decreased.
- As well density increased, the number of breeding males on affected leks decreased.
- Females strongly avoided nesting in areas of high well density.
- There was a 21 percent decline in the population of nesting females compared to undisturbed females over the 5 years of the study.
- Females nesting in developed areas had a significantly lower survival rate than female grouse in undeveloped areas. Although nest success rates were higher in developed areas, this increase was not sufficient to overcome the reduced female survival rates, resulting in an overall 21 percent decline in sage grouse population growth in developed gas fields compared to undeveloped areas.
- Population reductions likely result from a combination of dispersal away from gas fields and increased mortality rates for birds affected by development.
- The study's findings suggest, "current development stipulations are inadequate to maintain greater sage-grouse breeding populations in natural gas fields" (p. 57).
Of the 313 square miles of the Pinedale Anticline
field, only 7.3 square miles (approximately 2 percent) is not leased for
oil and gas development. The study predicted that
sage grouse populations would become extinct in the Pinedale Anticline
and Jonah development fields within 19 years if current population trends
continue.
Gas fields and wildlife