David Schaper, NPR
A purple martin nestling sits in a human-made nest in Chicago's Park District.
Purple martin nestlings inside a human-made nest in Chicago's Park District. David Schaper, NPR
David Schaper, NPR
Purple martin fledglings perch on the edge of their bird "apartment" on Chicago's lakefront, while a parent bird keeps watch.
David Schaper, NPR
Volunteer purple martin "landlord" Gary Thatcher checks on his "tenants."
Purple martins historically lived along Lake Michigan in the summer months, but development in Chicago long ago eliminated much of the birds' natural habitat in the city.
Now, just six years after the city of Chicago put up bird houses for the purple martins along the lakefront, the migratory songbird is thriving.
Purple martins aren't really purple. They're mostly black, with a glossy, steel-blue shine to their feathers that can look purplish in the sunlight. They are spirited songbirds and daredevil flyers, acrobatically darting through the sky in pursuit of tasty, large insects. The birds prefer to live in open areas and near water, where insects are plentiful.
Historically, they nested in hollows in old-growth trees. But Zhana Yemnikov, manager of natural areas for the Chicago Park District, says much of that kind of habitat around Chicago is long gone.
"Because they can't really compete with the starlings and other birds, their numbers really started to decline," he says.
It's not just a problem here. Everywhere east of the Rocky Mountains, purple martins nest only in human-made bird houses. For at least 15 to 20 years, they had disappeared from Chicago's lakefront.
Then in 2002, the Chicago Park District put up bird houses for purple martins in a handful of locations to try to lure them back. The district recruited volunteers to keep watch for the migratory birds' return from South America.
"There was some anxious moments that first spring," volunteer Bob Schleike says. "You know, we were coming out here every day, wondering if we were going to get them or not."
Schleike says birdwatchers knew that purple martins flew over the area but rarely stopped there.
"All of a sudden, one shows up one day, and I think we had just the one nest that first year," he says.
He adds, "It's roughly doubled each year since then, to a total of — now we've got, we came close to 100."
That's close to 100 offspring this year, from about 30 sets of parents — an amazing rate of success in the past six years.
"I would guess that we'd have maybe half as many birds if there weren't humans here helping them out," says volunteer Gary Thatcher.
Thatcher and other volunteers call themselves "landlords," and they take meticulous care of the purple martins' "apartments."
Thatcher says their primary job initially is keeping starlings from nesting in and invading the bird houses.
"I can't stress enough how destructive a starling is," Thatcher says. "Most people don't really comprehend it. Starlings are very aggressive, very mean, very similar to a rat. They take over by sheer numbers, and with the destruction and killing of the young of anything that is in their space, competing with them. So what we're doing is, basically, not giving the starling a chance to do that."
At least twice a week, Thatcher and the others lower the bird houses to check on the purple martins' nests. On a recent day, Thatcher checks on 16-day-old nestlings; he says the parents don't mind, and the check-ups help keep nestlings free from dangerous mite infestations.
In the next few days — as soon as all of the young are mature enough — the district's 150 or so purple martins will meet up with thousands of other purple martins, some coming from hundreds of miles away.
The birds will group together for one night somewhere along Chicago's lakefront — no one knows exactly when or where. Then, thousands of purple martins will leave together for the long trip to their winter home in Brazil.