The surviving eagle, an immature female spotted by a hiker near Centerville, arrived at the Ogden center Wednesday. Likely hatched this spring, the juvenile displays the same head tremors and lower extremity paralysis as the previous eagles, Erickson said.
As the mystery persists. Erickson is afraid "what we are seeing is only the tip of the iceberg."
Six distressed eagles have been reported by members of the public and delivered by Utah Division of Wildlife Resources officials to the Ogden center or the Great Basin Wildlife Rescue in Mapleton.
Two of those eagles came from West Weber. The others have come from Corrine, Grantsville and Lehi. One of the dead birds was found on the Provo River Trail in Utah County.
Preliminary results from the first birds' tests for illnesses including West Nile virus, lead poisoning and avian cholera are expected to arrive late this week or early next week from the National Wildlife Health Center in Madison, Wis.
Results from more thorough testing to hone in on the exact cause of the deaths will likely not be available until after Christmas.
It is likely that the dying eagles recently migrated to Utah from other states.
Leslie McFarlane, wildlife disease specialist with the DWR, has contacted surrounding states and none reported unusual bald eagle deaths.
McFarlane worries that the increasing arrivals of migrating eagles could compound the number of deaths if it turns out that the cause is an illness that can be passed from bird to bird.
"More eagles are arriving every day. I'm absolutely concerned," she said.
Eagles gather in Utah each winter and tend to stay where food sources are easily available. Farmington Bay Waterfowl Management area in the Great Salt Lake marshes is a good example.
McFarlane said annual winter counts of bald eagles in Utah, scheduled to start in coming weeks, range from 750 to more than 1,200.
The DWR is exploring whether the eagle deaths are linked to the recent deaths of approximately 1,000 eared grebes on the Great Salt Lake and the discovery of 150 dead northern shovelers on Interstate 80 just south of the Great Salt Lake.
McFarlane isn't sure there will be a connection. "We just need to look at everything and hope we can come up with an answer," she said.
Wildlife officials ask people who spot distressed or dead eagles or other wildlife to contact local DWR offices (Ogden, Vernal, Springville, Cedar City and Price) with the location of the animal. The Help Stop Poaching Hotline 1-800-662-3337 is another option on weekends and holidays and after hours.