ROBERT SIEGEL, host:
This is ALL THINGS CONSIDERED from NPR News. I'm Robert Siegel.
Time was, Purple Martins took up summer residence in Chicago along Lake Michigan. Then, the city grew. The birds largely left. And six years ago, Chicago tried to make amends with new birdhouses all along the lakefront.
Now, thanks to these human-made shelters and their landlords, the Purple Martins have returned.
Here's NPR's David Schaper.
(Soundbite of Purple Martins chirping)
DAVID SCHAPER: Purple Martins aren't really purple. They're mostly black, with a glossy steel-blue shine to their feathers that can seem purplish in the sunlight. They are spirited songbirds and daredevil flyers, acrobatically darting through the sky in pursuit of tasty, large insects. Purple Martins prefer to live in open areas and near water where insects are plentiful. Historically, they'd nest in hollows in old-growth trees.
But Zhanna Yermakov, Natural Areas Manager for the Chicago Park District, says much of that kind of habitat around Chicago is long gone.
Ms. ZHANNA YERMAKOV (Natural Areas Manager, Chicago Park District): But because they can't really compete with the starlings and other birds, their numbers really started to decline.
SCHAPER: It's not just a problem here. Everywhere east of the Rocky Mountains, Purple Martins only nest in human-made bird houses. And for at least 15 to 20 years, they had completely disappeared from Chicago's lakefront.
In 2002, the Chicago Park District put up birdhouses for Purple Martins in a handful of locations to try to lure them back, and the Park's recruited volunteers including Bob Schleike to keep watch for the migratory birds' return from South America.
Mr. BOB SCHLEIKE (Volunteer, Chicago Park District): There was some anxious moments that first spring. You know, we were coming out here every day, wondering if we're going to get them or not.
SCHAPER: Schleike says birdwatchers knew they flew over the area but rarely stopped.
Mr. SCHLEIKE: And then all of a sudden, one shows up one day. And I think we had just the one nest the first year. And it's roughly doubled each year since then, to a total of - now we've got - we came close to a hundred.
SCHAPER: That's close to a hundred offspring this year from about 30 sets of parents, an amazing rate of success in the past six years.
Mr. SCHLEIKE: I would guess that we'd have maybe half as many birds if there weren't humans here helping them out.
SCHAPER: The human volunteers call themselves landlords. And they take meticulous care of the Purple Martins' apartments.
Gary Thatcher says their primary job initially is keeping starlings from nesting in and invading the birdhouses.
Mr. GARY THATCHER (Volunteer, Chicago Park District): I can't stress enough how destructive a starling is. Most people don't really comprehend it. Starlings are very aggressive, very mean. It's 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, is not giving the starling a chance to do that.
SCHAPER: At least twice a week, Thatcher and the others lower the birdhouses down to check on the Purple Martins' nests.
Mr. THATCHER: The house is up on about 15-foot pole. And we have them on a -hooked up to a wheel(ph) system where they'll just ride down the pole nice and smooth.
But parents, sometimes they won't even fly out of the house until you're, like opening the door. They are that accustomed to us. This one just - the newer one - he just flew out. And so did the mom. And now, we're going to take a look at some babies.
SCHAPER: The little nestlings are about 16 days old. And debunking an old wives' tale, the volunteers can handle them, and the parents don't mind one bit, especially, Thatcher says, when they can save the nestlings from a dangerous mite infestation.
Mr. THATCHER: What we do then is we take that nest box - the inserts from that apartment out.
SCHAPER: Replace the nest.
Mr. THATCHER: Replace the nest. And then we take each of the babies that were in that nest and clean all the mites off. And then we then return them to the nest.
SCHAPER: The Purple Martins' apartment is then closed back up. It goes back up the pole. And by then, the mother and father bird are usually waiting with a big, juicy insect in their mouths, ready to feed their young. Within the next few days, as soon as all of the young are mature enough, the 150 or so Purple Martins here will meet up with thousands of other Purple Martins, some coming from hundreds of miles away. They'll group together for one night somewhere along Chicago's lakefront - no one knows exactly when or where. So these thousands of Purple Martins can leave together for the long trip to their winter home in Brazil.
David Schaper, NPR News, Chicago.