Raptors' die-off spreads fears of West Nile virus

A mysterious outbreak in the upper Midwest may extend to other birds

September 30, 2002|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

ANTIGO, Wis. - In an old incubator salvaged from a hospital nursery, a young red-tailed hawk lies flat on its belly, swaddled in a white terrycloth towel and a pink blanket.

Except for the rise and fall of its body as it breathes, the bird is utterly still. It doesn't react when Marge Gibson, a raptor rehabilitator, puts her hand inside the incubator.

"Her eyes are open, but we don't know how much she's taking in," Gibson says.

At least the hawk is alive. She is a survivor, for now, of a mysterious outbreak of neurological illness and death among hundreds - and quite likely thousands - of hawks, eagles, owls and falcons across the upper Midwest.

Since early August, from Iowa to Kentucky to Ontario, raptors have been found starving, anemic and dehydrated, unable to walk or fly, or swallow. Those that survive suffer from high fever, paralysis, tremors, weakness, convulsions and partial blindness.

"We've seen epidemics before," said Patrick Redig, director of the Raptor Center at the University of Minnesota, who has been working with birds of prey for almost 30 years. "But this eclipses anything I've ever seen, and certainly anything I've ever imagined."

The die-off may extend beyond the raptors. A recent Audubon Society report noted the scarcity of crows in the Chicago area. And Midwestern birders have noted the disappearance of many songbirds.

"I spend a lot of time canoeing on the St. Croix River," Redig said, "and it is just darn quiet out there."

A prime suspect is the West Nile virus. The mosquito-borne pathogen causes encephalitis, an inflammation of the brain, primarily among birds and horses, although more than 2,200 humans also have been stricken in the United States this year - 108 fatally.

Many of the raptors are testing positive for the virus. But if this is a West Nile epidemic, investigators say, it is unlike anything seen since the virus began moving south and west from New York in 1999.

`So darn surprising'

Until now, its arrival has always been signaled first by the wholesale deaths of crows, but only a handful of raptors.

"That's the thing that is so darn surprising to all of us," Redig says. "We knew it would get here sooner or later. But we didn't think it would hit raptors so hard. It begs the question: What changed? I don't know."

There is rising concern that as the virus spreads west, it will threaten the recovery of such rarities as the aplomado falcons in Texas and 73 California condors living wild in the Southwest.

At the nonprofit Raptor Education Group Inc. in Antigo, Gibson, her husband, one paid assistant and a shifting cast of volunteers are racing to save desperately sick birds.

"On Aug. 16, we got our first case," she says. It was the red-tailed hawk, found by the side of a road. The bird was presumed dead until Gibson's assistant noticed an eyelid flicker.

Then the phone calls started coming "in droves," Gibson said. There were seven to 10 a day. Birds were being brought in from all over Wisconsin and the adjoining Upper Peninsula of Michigan - Cooper's hawks, sharp-shinned hawks, bald eagles, great horned owls, red-tails, a merlin falcon and more.

"It was absolute chaos," she says. "We're not funded by the state or federal government. We operate on a small budget. We don't even have a secretary to answer the phone."

Each new arrival was added to a status board, in colored marker, with a brief description: a bald eagle, "toxic and very thin"; a red-tailed hawk, "dehydrated and starving"; a nighthawk, "didn't fly away"; another bald eagle, "partially blind."

There were 27 raptors on the board last week. Many, like the red-tail hawk, arrived virtually catatonic. Some were more responsive but disheveled, weak and feverish. Many others arrived dead, or died within a day or two.

The hawk in the incubator arrived with a fever too high to register on a thermometer calibrated to 111 degrees. "Normal" for a hawk is 104.

Many had to be hand-fed - rats and mice - or tube-fed with pureed meat baby food. "All of these cases are incredibly labor intensive," she said.

Gibson and her helpers soon began putting in 20-hour days. They canceled the center's educational programs. They canceled sleep.

Gibson, 57, a former medical technologist, has worked with birds for 40 years. She and her husband, Don, a retired pathologist, built the rehabilitation center 10 years ago. It stands on 70 acres of woods and meadow outside Antigo, about 200 miles northwest of Milwaukee.

With state and federal permits, Gibson cares for raptors, sandhill cranes, trumpeter swans and other birds found orphaned, poisoned, shot, burned by power lines, hit by cars or just sick.

`Hadn't seen it at all'

At first, she says, when all the raptors began arriving with neurological symptoms, "we were thinking organophosphates" -herbicide or pesticide poisoning.

West Nile had just begun to kill crows in Milwaukee last year. "But we hadn't seen it at all, not even crows," she says.

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