by Koren
Wetmore
You know the world's gone
high-tech when eagles send e-mail. Yet bird messages are commonplace
for Janet Linthicum, a research associate with the Santa Cruz
Predatory Bird Research Group. Each day Linthicum
receives up to 20 electronic notes from 13 bald eagles that she’s
tracking on their
migration routes from California to nest sites up north. Two of the
eagles are among the 30 that winter in the San Bernardino
Mountains.
“We always knew the birds went
north, but before the study, nobody knew how far they went,”
Linthicum says. An adult tracked from
Silverwood Lake this year flew 2,000 miles to nest along
the Great Slave
Lake in
Canada’s Northwest
Territories. An immature eagle tagged here last year
prefers to summer along the Athabasca River in Central Alberta,
Canada.
The technology behind the birds
is as amazing as their travel plans. Unlike their peers, the studied
eagles wear a backpack that houses a transmitter. About the size of
a matchbox, the 70-gram pack equals two percent of the bird’s body
weight. Its straps leave room for wing movement and are designed to
wear out in about three years (the approximate lifespan of the
transmitter). “They don’t seem to notice it’s there,” Linthicum
says. “They preen the feathers under and around
it.”
Signals from the pack are picked
up by several satellites, which calculate and feed data on the
bird’s location to a computer in Seattle. The computer then relays the
information via e-mail.
The system recently revealed
information about eagle movement that radically changes how
biologists view bird territory...
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