"We don't yet know whether the sage-grouse are more at risk than other species but we do know that the West Nile virus could have devastating consequences for small populations," said Aldridge, a co-author on a research paper just published in "Ecology Letters."
Aldridge was part of a team that monitored radio-marked female sage-grouse from March 2003 to September 2004 in five sites in Alberta, Montana and Wyoming. They found that populations that had their first exposure to the virus in 2003, had a 25% decrease in late summer survival of females. West Nile virus was confirmed to have killed 18 individuals whose carcases could be relocated. Serum from 112 sage-grouse collected after the outbreak show that none had antibodies, suggesting that they lack resistance.
"When we tested individual sage grouse after the outbreak of the virus in 2003, we hoped we would find antibodies present for the virus, indicating some birds were infected, fought off the virus and survived, but we didn't see that," said Aldridge, a PhD candidate in the Faculty of Science. "The immunity appears to be extremely low for sage-grouse, which means it is going to take much longer for the population to develop resistance to the virus and to survive, if they are indeed capable. We don't know how long small populations like those found in Alberta or Saskatchewan can survive, while losing the genetic basis needed to maintain the population, but we may
Contact: Phoebe Dey
University of Alberta