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Spring
2003
Biologists and Volunteers
Find Rich Vein of Spring Migrants
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 Photo
by Carol Freeman
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A long-term bird banding project launched
last spring in southeast Lake County is supplying hard evidence
that the Chicago area provides critical stopover territory
for woodland migrant birds.
The Shaw
Woods Avian Monitoring Project (SWAMP) recorded the
second-highest capture rate of similar stations in north
and eastern North America, 1.19 birds per net-hour. "People
told me this area was crawling with migrants," said
project leader Caleb Gordon, assistant professor of biology
at Lake Forest College, "and now we can put a number
on it." Only Black Swamp Bird Observatory in Ohio returned
a higher rate of capture.
These high bird numbers were proportionally
rich in species experiencing significant population declines
such as the wood thrush and the veery, which underscores
the importance of Chicago's natural areas to these birds.
Gordon hopes the data will, over time, reveal more about
species population trends as well as their "stopover
ecology" — the routes, behaviors, and needs of
migrants on their flights north to breeding grounds. Over
the last two decades, biologists have focused on breeding
and wintering grounds. The SWAMP project probes the next
research frontier — what happens in between.
For three weeks in May, Gordon worked
with 40 volunteers, hanging 12-meter-wide mist-nets in the
understory of a muddy woodland along the Skokie River at
Lake Forest Open Land Association's Skokie River Nature
Preserve. They brought 884 birds to the banding table to
measure, band, and quickly release them. Fifty-three species
of birds flew into the nets, including large numbers of
what Gordon describes as the "sneaky species of the
understory" such as the mourning warbler (full species
counts are listed on the project's Web site).
"With a bird in hand, you collect
a richness of data you can't get from observational studies,
such as molt, wing wear, age, sex, weight, fat, and parasite
loads," Gordon said. Since banding records enter a
national database, they trace routes of individual birds,
such as a veery banded in Ripon, Wisconsin, and recaptured
in a SWAMP net. Birds caught more than once in a season
at Shaw Woods help clarify how long migrants spend feeding
at stopovers before continuing north. With plans to continue
the study as long as possible, banders may find familiar
birds returning to the preserve on later migrations.
Gordon calls his project good citizen
science. "Local birdersget to see, experience, and
photograph birds in the hand," he said, "while
providing an indispensable means of collecting data."
For more information or to volunteer,
contact Caleb Gordon at gordon@lfc.edu.
—Ryan Chew
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