There's one Minnesota bird that has an unusual habitat problem. Chimney swifts have adapted in the past as humans encroached on their territory.
But now changes in human behavior are presenting new problems for these voracious insect-eaters. And some people are trying to help them adapt again.
In his father's window-and-door warehouse in the western suburbs, Derek Meyer is supervising the boys in his Scout troop as they build a wooden tower for chimney swifts.
They're using rough plywood to build a narrow box 12 feet high, with an opening about a foot square.
Derek Meyer is doing this project to earn the rank of Eagle Scout. In the process, he's learned a few things about the lives of Chimney Swifts.
"They originally lived in hollow trees. But when the settlers from Europe came over they started destroying the trees, so they decided to live in the chimneys," said Meyer. "And then people started putting wire over their chimneys, so over the last 40 years they've lost half of their population."
Not just wire, but rain caps and other devices to keep birds and other critters out of chimneys.
The new home these boys are building for chimney swifts is destined for the nature center next to the Orono schools. The school district was planning to tear down an old brick chimney as part of a remodeling project. Rebecca Field found out about that, and she tried to stop it.
"I said, 'Wait a minute. I'm sure there are chimney swifts in there, and they're really good birds because they eat about 2,000 insects a day, each of those birds. And their favorite insect is the mosquito.'"
Field is on the board of Audubon Minnesota, and she'd been watching the swifts hanging around the chimney in the evenings. Individually they look like fat cigars with wings, but when they get ready to swoop down into the chimney for the night, there are so many of them, they look like a funnel cloud.
"How they communicate I have no idea, how they put the brakes on when they dive into that chimney so quickly, it's a mystery. But it's a fun thing to watch," Field said.
In the end, the school district decided to leave the chimney up.
So now, a few weeks later, and just in time for the chimney swifts to fly back up from the Amazon, the tower is standing on a concrete pad at the Orono schools nature center.
School naturalist Marleane Callaghan has already brought all her classes, grades 3-5, to check it out.
"We've talked about the bird, what it looks like, the dimension of it," said Callaghan. "I've invited them to come back with their parents to watch in the school parking lot in the evening, up at the high school where they've left the chimney, and then to walk on down, to be able to identify them."
This project is part of an effort by Audubon Minnesota to raise awareness of Chimney Swifts and their need for homes.
In addition to installing new towers, project director Ron Windingstad wants to convince homeowners to make existing chimneys more welcoming. He says people can take the rain guards off their chimneys during the summer, or just raise them high enough so the birds can fly in from the sides.
Soon these school kids will be able to see the amazing acrobatics of the chimney swifts. Windingstad says they hardly ever stop flying, from morning until night. They'll even sip water and take a bath in a nearby pond, without stopping.
"They'll scoop down, lower their bill, and fly across it and drink in the water," said Windingstad. "They'll use some of these shrubs around here to break off little twigs, about the size of a wooden matchstick or toothpick, and use that to build their nests. And they do that while flying as well. They are marvelous creatures."
Swifts can eat one-third of their body weight in insects every day -- that's a useful addition to any neighborhood.