Sage grouse numbers are down in northeast Wyoming for a second year in a row and have reached their lowest levels since 1995, according to a state game official.
"We had an upward trend through 2007, now we're on a downward trend again," said Dan Thiele with the Wyoming Game and Fish. "(It is) a pretty significant decline from 2008."
There is no accurate method for estimating actual grouse population numbers. But sage grouse population trends can be followed by monitoring the average number of males on breeding grounds each year.
Thiele and Tom Maechtle, chairman of the Northeast Wyoming Sage Grouse Working Group, stressed that the downward trend is, in part, due to the bird's natural population cycle.
Grouse go through about four-year cycles of increasing and decreasing population, Maechtle said. The area has been in a downward trend of the cycle for the last few years.
Northeast Wyoming also has extensive oil and gas development, which disturbs grouse habitat.
But while oil and gas development is a factor, it is not the only one. The wet weather during the 2008 breeding season also could have hurt sage grouse population, Thiele said.
Tom Christiansen, sage grouse coordinator for the Wyoming Game and Fish Department, said sage grouse numbers statewide are higher than the numbers in northeast Wyoming.
"The statewide average is well above what it is here. Some of that is natural, some of it isn't," Christiansen said.
The U.S. Fish and Wildlife Service is studying whether to protect the sage grouse under the Endangered Species Act. A decision on whether to proceed with listing is expected at the end of February.