- The great horned owl cradled by a technician in St. Paul
was trembling, but not from fear. The bird normally would have put up a
vigorous struggle and clacked its beak, but it was sluggish and weak as
its giant yellow eyes blinked slowly.
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- The owl is one of about 40 raptors taken to the University
of Minnesota's Raptor Research Center in the past three weeks. They have
been sick, almost certainly from the West Nile virus. All but a handful
have died or been destroyed.
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- "I don't think it'd be exaggerating to say that
several hundred owls and red-tailed hawks in Minnesota have been affected,"
said Dr. Patrick Redig. "We don't know where this is going."
-
- Officials have known for years that the West Nile virus,
first detected in North America in 1999, is spread by mosquitoes and affects
humans, horses and birds. Until a year ago, about a dozen bird species
were known to be hosts to the virus, primarily crows and blue jays, which
have been dying in huge numbers.
-
- But the latest estimates are that 110 to 120 bird species
have been infected, according to Emi Saito, West Nile surveillance coordinator
at the National Wildlife Health Center in Madison, Wis. The center has
found the virus in everything from endangered Mississippi sandhill cranes
to ruby-throated hummingbirds.
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- It is too early to know whether certain species, endangered
or not, might be decimated by the virus, she said.
-
- Concern for raptors popped up after thousands of hawks
and owls died in Ohio in late July, Saito said. Soon afterward, the Wisconsin
center began receiving reports of sick and dead raptors from Indiana, Kentucky,
Michigan, Illinois, Missouri, Louisiana, Nebraska, Iowa, Wisconsin and
Minnesota.
-
- Raptor rehabilitation centers that normally receive five
to 10 birds a week suddenly started seeing more than 100 per week, Saito
said. "Something's going on with the raptors," she said, but
whether it's the West Nile virus alone is unclear.
-
- The Minnesota Health Department has confirmed the West
Nile virus in nine owls and hawks. Redig, the Raptor Center's director,
expects that tests for all or most of the other raptors he has seen will
confirm the virus, because they had similar symptoms: disorientation, lack
of focus, inability to stand or fly, extreme thinness and tremors or seizures.
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- "By any definition this is an epidemic," Redig
said. Nature will eventually adapt, he said, but at the moment the West
Nile virus is a novel pathogen that is causing mass death.
-
- Some birds in the wild may get a mild form of the disease
and develop immunity, he said. "There are probably all gradations
of severity, like when people get influenza," he said. "Some
get the sniffles, some get wretchedly sick and some die from it."
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- So far most of the raptor casualties, nationally and
in Minnesota, have been great horned owls and red-tailed hawks. Redig said
Cooper's hawks, merlins and one goshawk have been brought to the center.
No bald eagles in Minnesota are known to have died, he said, but at least
one eagle death has been confirmed in Wisconsin.
-
- Redig said that there is no treatment but that a few
of the healthier raptors brought to St. Paul are being kept alive with
daily injections of vitamins, fluids and anti-inflammatory drugs. But their
full recovery is uncertain, and they might not be returned to wild.
-
- Laura Erickson, an ornithologist and educator in Duluth,
is concerned that many bird species now beginning to migrate south from
Canada could become infected by mosquitoes that carry the virus.
-
- Redig is hoping that cooler weather in northern states
will soon kill the mosquitoes, giving him and other researchers time to
compare notes. They hope to develop a vaccine for captive raptors in zoos,
rehabilitation centers and research centers.
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- "This virus will now be part of the landscape forever,"
he said. "It won't go away."
-
- -- Tom Meersman is at meersman@startribune.com.
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- © Copyright 2002 Star Tribune. All rights reserved.
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