Jim
Williams, Special to the Star Tribune
Ruby-throated
hummingbird, juvenile male, at geranium flower
As ruby-throated
hummingbirds are returning to the state, researchers are learning more about
where they spend the other half of the year.
By VAL CUNNINGHAM, Contributing Writer
Around the first of May each year, ruby-throated hummingbirds
begin returning to the midwest. Wonder where they’ve been all winter?
So do the scientists.
At the end of each
summer, some 7 million ruby-throats from across the eastern United States and
Canada essentially disappear.
There are indications
that they travel to the tropics, going as far south as Panama. But hummingbirds
are so common in Central America that few people even notice them, much less
track them. These little mountain birds also disperse widely, making it even
less likely they’d draw attention. So, much of what we know about ruby-throats
outside the United States is based on assumptions.
A South Carolina
naturalist and educator is working to change that.
Bill Hilton Jr. has been
banding U.S. ruby-throats for decades. Over the years, Hilton and others have
slipped tiny aluminum rings on more than 200,000 hummingbirds. Still, none of
the banded birds have been reported in Central America.
And the value of banding
birds lies in them being reported after being caught by another bander or found
dead. It’s only when a banded bird is rediscovered that researchers can learn
where its band was attached. That, in turn, tells a great deal about a bird’s
itinerary.
But Hilton isn’t giving
up. For the past several years, he’s been leading groups of volunteers to the
other end of the migratory trail. In winter, they head to Costa Rica to study
and band hummingbirds there.
The banders found an aloe
vera plantation popular with ruby-throats. By banding a few dozen of these
birds over several years, Hilton could tell that the same ruby-throats were
returning from year to year, a practice called “site fidelity” in ornithological
circles.
To date, an estimated 400
ruby-throats have been banded on their tropical wintering grounds. That’s a
small percentage of the estimated population. But the banding work has already
proved its worth: The birds that return each year to the aloe plantation send a
strong message about conserving such sites.
“Site fidelity like this
gives us pretty powerful evidence when we talk about the need to protect the
birds’ habitat,” said Hilton.
And, in the summer of
2008, Hilton got some exciting news. A bird he’d banded in Costa Rica had
turned up in the United States.
This hummingbird,
encountered in Georgia, was the first-ever ruby-throat banded in Central
America to be captured in the United States. That makes it the first hard
evidence that ruby-throats migrate back and forth.
You can help
If you’re a hummingbird fan, you can help learn more about these
birds. Here’s how: If you come across a ruby-throat with a band on its leg,
contact the federal Bird Banding Laboratory. Either fill out a form on its web
page (www.pwrc.usgs.gov/bbl/)
or call 1-800-327-BAND. They’ll ask for the band number and where the bird was
found, and report this information to the original bander.
If you’d like to join one of those winter bird-banding trips to
the tropics, go to www.hiltonpond.org and click on hummingbirds.
Val Cunningham, a St. Paul resident, writes about nature for
local and regional newspapers. She’s also the author of “The Gardener’s
Hummingbird Book.” She can be reached at valwrites@comcast.net.
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