Bald eagle deaths in Utah alarm and mystify scientists
29
December, 2013
SALT
LAKE CITY — Bald eagles are dying in Utah — 20 in the past few
weeks alone — and nobody can figure out why.
Hundreds
of the majestic birds — many with wing spans of 7 feet or more —
migrate here each winter, gathering along the Great Salt Lake and
feasting on carp and other fish that swim in the nearby freshwater
bays.
Earlier
this month, however, hunters and farmers across five counties in
northern and central Utah began finding the normally skittish raptors
lying listless on the ground. Many suffered from seizures, head
tremors and paralysis in the legs, feet and wings.
Many
of the eagles were brought to the mammoth Wildlife Rehabilitation
Center of Northern Utah, where Buz Marthaler — a longtime animal
caretaker — and other handlers tried to save the birds. Within 48
hours most were dead.
“It’s
just hard to have your national bird in your arms, going through
seizures in a way it can’t control — when you can see it’s pain
but don’t know what’s happening to it,” said Marthaler, 56,
co-founder of the facility in Ogden.
“As
a human being, you just have problems with that. And when you lose
one, it just grabs your heart.”
State
wildlife specialists are also baffled. For weeks, officials have sent
birds for necropsies at the National Wildlife Health Center in
Madison, Wis., hoping the results would offer clues.
They
began to rule out obvious possibilities: The birds were not shot by
hunters, and officials don’t believe the birds were poisoned.
“There doesn’t seem to be anything suspicious in that regard,”
said Mitch Lane, a conservation officer with the Utah Division of
Wildlife Resources, who has responded to numerous reports of downed
or sick eagles.
At
first, the agency’s disease scientists guessed that the illness
could be encephalitis, which is caused by the West Nile virus, but
later ruled out that possibility. And although many sick eagles
tested positive for lead, researchers did not think that it was
killing the birds.
Officials
suggest the eagle die-off is possibly connected to the deaths of
thousands of eared grebes that began in Utah in November. Eagles are
known to prey on the small shore birds. Because the grebes are
thought to have died from avian cholera, many scientists theorize
that the eagles became sick from feeding on infected grebes.
Officials still don’t know why the shore birds became sick.
“We’re
getting closer to an answer,” Lane said, adding that officials
would meet this week to continue investigating the mystery.
Meanwhile,
a new ailing bald eagle surfaces almost daily.
Scott
Isaacson, 59, an attorney who lives in the town of Farmington, said
he was feeding his chickens one night this month when he spotted an
eagle on the ground under a cottonwood tree where he was used to
seeing seven or eight birds perched in the branches. “I’ve never
seen one on the ground,” he said.
He
called wildlife officials, who told him to approach bird; if it was
healthy, it would fly off. The bird skittered into a nearby pond.
“It
was really sad to see this graceful creature, with its beautiful
white head, its wings spread out in the water,” he said.
Wildlife
officials later nabbed the bird, which was hissing and clawing as it
was scooped up in a net.
Bald
eagles were removed from the endangered species list in 2007. Utah
officials say 700 to 1,200 winter here each year. “Everybody here
loves the eagles,” Isaacson said. “Our school is named Eagle Bay
Elementary and our church is the Eagle Shore Church.”
Many
sick eagles were brought to Marthaler’s facility in dog carriers.
Workers handled them with Kevlar-lined gloves to avoid being sliced
by the powerful talons.
“In
an average year, we might get one or two, but we’ve received nine
so far, and five of those have died,” Marthaler said. “The other
four are still in our care.”
Some
days have been especially hard on the staff. “Every bird would come
in more paralyzed than the one before it,” Marthaler said. “They
couldn’t move their legs. Their wings were weak. Their heads would
jerk with tremors. It was difficult to watch.”
The
retired Air Force member said it’s often difficult to determine the
ages of adult eagles. “With their plumage, they can be 5 or 20;
it’s hard to tell,” he said.
Officials
at the Wildlife Rehabilitation Center have their own theories about
the sickness. Some point to radiation from Japan after the 2011
meltdown at the Fukushima Daiichi nuclear power plant. “We aren’t
ruling out anything,” Marthaler said. A call from Idaho shed new
light: A wildlife official said bald eagles there were also getting
sick, suggesting that the birds were arriving in Utah already in bad
heath.
The
most recent eagle to arrive with Marthaler was a juvenile. “He was
in the worst condition of all of them,” he said. “He wasn’t
even able to stand. When we left for the night, he was lying down and
you had to look close to see if he was still breathing.”
The
next morning, the bird was standing again. “He’s still with us,”
Marthaler said. “And that gives us a bit of hope.”
No comments:
Post a Comment
Note: only a member of this blog may post a comment.