Radio collars were to be attached to several moose this month in a herd of between 40 to 60 moose near Elgin and Westin, said Pat Matthews, an Oregon Department of Fish and Wildlife biologist in Enterprise.
Two moose, a bull and a cow, were wearing radio collars when they died last summer, so biologists were able to locate their bodies.
The biologists were unable, however, to determine a cause of death and at the time didn't know to look for the carotid artery worm, Elaephora schneideri, isolated three years ago in moose herds in Wyoming, the (Portland) Oregonian reported Monday.
Biologists in Oregon have seen moose with cropped ears, a symptom of the deadly parasite, Matthews said. In cold weather, the worms obstruct blood flow, causing ear tips to freeze and fall off. Deer, elk and goats carry the parasite, but have wider blood vessels, which keeps the worms from causing damage.
The Shiras moose, also known as the Yellowstone and Wyoming moose, is the smallest of the moose found in North America.
Notable deaths of 2014 [PHOTOS]