What's killing trumpeter swans in Washington?

NEAR LYNDEN, Wash. -- Majestic trumpeter swans, the largest of all waterfowl, whose wingspans can reach eight feet, are dying at a higher than normal rate in their winter haven in northern Puget Sound. And Washington State Department of Fish and Wildlife biologists think they know why.

They've counted 261 dead swans so far this winter in Whatcom County. That's about a 75 percent increase over the normal death rate in winter when their physical and environmental challenges are greatest.

"We believe and have some evidence that aspergililosis is playing a factor in the mortality," said state wildlife biologist Chris Danilson, while standing near a Skagit Valley field dotted with Trumpeter Swans and drenched in brilliant winter sunshine.

"It's a fungus that they'll usually pick up in the feed that they're eating," he said. "So a lot of times it's in the grains or corn, wastage in fields left over from the harvest. It can get moldy."

On Wiser Lake in Whatcom County northeast of Lynden, trumpeter swans are dominating the habitat, and they are loud. Yes, they really do sound like trumpets. Ken and Pam Goto have a sweeping view of them.

"It does concern me, yes," Pam said. "Once in a while we'll see - when it's frozen - we'll see a swan sick and an eagle sitting and waiting for it, to eat it, you know. It's very sad."

Trumpter swans have made a big comeback in recent decades in western North America since hunting was banned and other protections put in place. Indeed, northern Puget Sound has, according to Danilsen, an estimated 14,421 trumpeter swans now. That's up from about 5,000 20 years ago.

So losing a few hundred to a naturally occurring disease is not devastating, according to Danilson.

"So I would say this is something that just occurs and we don't have a lot of control over it and what we've seen so far is it's not a major, major event," he said.