One group, the Gaylord Nelson chapter of the Audubon Society, plans to start a mapping project to track the birds in northwestern Wisconsin, the Eau Claire Leader-Telegram reported.
Purple martins are the largest of the swallow family in Wisconsin. They are communal nesters and depend on man-made birdhouses - those multi-unit houses built on high poles - for lodging.
"They're in trouble," local bird watcher Steve Betchkal said of the birds. "The old timers used to build those houses for them, but they're no longer doing that ... There used to be a purple martin house at everybody's farm. Now they're gone."
His group hopes to find every active martin nest, as well as the sites where the birds historically nested in the area. Group members will record GPS coordinates and a written description of each purple martin and colony.
Betchkal, a member of the local Audubon Society chapter who has been watching birds for 46 years, said last year was the first in which he did not hear or see a purple martin in the state.
Other factors besides housing may be affecting the martins. The birds face competition from house sparrows and starlings. In addition, martins eat insects and are vulnerable to cold weather. Last year, when there was snow in early May, some martins starved when they couldn't find food, Betchkal said.
Chad Mogen, a wildlife technician with the state Department of Natural Resources in Menomonie, is attempting to reintroduce martins there. He said birdhouse builders shouldn't be discouraged if purple martins don't show up at first. But Mogen said the birds are known to be picky, so if no martins settle in a house after a number of years, the house may need to be moved.