For these tenants, a wood shack is as good as a palace.
A bird's demands are simple: walls, a floor, a roof over its head and a round door just large enough to squeeze through.
"You put it up and they'll find it," said Stephen Kress, vice president for bird conservation at the National Audubon Society. "The black hole of the right size is a huge magnet for birds at the right season."
You can buy readymade birdhouses at prices up to $100 or more, or build your own for $5 to $10 in materials.
"You're really helping those birds out by putting nest houses up," said Michael Warriner, an information officer who also works with insects at the Arkansas National Heritage Commission in Little Rock.
Warriner became interested in birdhouses in college. Later, he and his father-in-law, Hugh Gregory, worked together on different designs.
"It's just an easy thing to do," he said. "Four walls and a roof and a bottom and you're pretty much done."
The first thing to consider when building a birdhouse is what kind of bird you want to attract. The bigger the bird, the bigger the house. And "different kind of birds have different hole requirements," Kress said.
Barb Pederson of Edina, Minn., did some research at the library after she and her husband decided to build 14 birdhouses as Christmas gifts for family and friends. They chose four patterns, each of which would attract a different bird, and started a production line of sorts, using cedar they had around the house. "Each one took us about eight hours of cutting and figuring and gluing and nailing and screwing," she said.
GETTING STARTED
Any untreated wood can be used for a birdhouse. But cedar, cyprus or fir will last longer than pine or maple, Warriner said.
Birdhouse walls should be about an inch thick, according to a guide from the Fish and Wildlife Service. If the wood is smooth, Warriner recommends scoring the interior walls with a knife or roughing it up so baby birds will be able to climb out. One of the walls or the bottom should be able to pivot out to facilitate cleaning.
The roof should be sloped, to allow water to drain off. And the entrance hole should be about two-thirds up from the bottom, which makes it less accessible to predators and allows the birds to build their nests without blocking the door.
Don't forget drainage " small holes cut in the corners of the floor " and ventilation in the top.
This is one case where perfect craftsmanship might not be desired. "You don't want the roof to fit too tight at the sides," said Kress, author of "The Audubon Society Guide to Attracting Birds." "If there are some cracks, it's fine."
He also suggests predator guards: another piece of wood with a hole the same size as the entrance that is attached to the front of the house. A thin plate of copper or another metal also can be placed around the hole to prevent squirrels from chewing a bigger hole to gain access.