Neither a tree-dweller nor a night bird, and roughly the size of a chicken, the Gunnison sage-grouse is not a particularly secretive bird yet just recently has it been identified as a new species of bird. The collaborative research designating the bird as a new species was conducted by researchers at the U.S. Geological Survey, University of Denver, Western State College of Colorado, Colorado Division of Wildlife and Colorado State University. The new species is recognized in the December issue of the Wilson Bulletin, which includes a discussion of the genetics research that conclusively proved the species designation.
Historically, scientists had believed that the newly named Gunnison sage-grouse, found in the sagebrush ecosystem of southwestern Colorado and southeastern Utah, was the same species as the Greater sage-grouse, which is found in northern Colorado and throughout 11 western states and two Canadian provinces. But over the years, differences in body size and unique plumage and behaviors led scientists to question this kinship.
Compiling the evidence needed to formally designate a new species is no easy task, said Dr. Jessica Young of Western State College of Colorado who led the effort along with Clait Braun, formerly with the Colorado Division of Wildlife. In this case, the final confirmation drew on the growing field of conservation genetics and involved a detailed DNA analysis of the two groups of grouse.
Because evidence of reproductive isolation is one criterion by which species designations are made, notes Dr. Sara Oyler-McCance, a conservation geneticist with the U.S. Geological Survey, the researchers used powerful DNA markers to determine whether gene flow, or interbreeding, had occurred between the two groups of sage grouse. We discovered that gene flow between the two grouse was absent and that the two groups were too distantly related to be considered the same species, said Oyler-McCance.