MILFORD – In the moment between day and night, woodcock dart through the purple sky with a frantic rustling of wings. This brief, frenzied flight is probably the only time you’ll see these odd little residents of the Maine woods.

Woodcock are essentially shorebirds that moved to the forest. Over time, they evolved a unique lifestyle to take advantage of disturbance, and have thrived while Mainers cleared land for farming and paper making.

But recently, the woodcock population in the East has been declining by as much as 2.5 percent each year. Human use of the land is changing, and nature hasn’t been able to adapt quickly enough to a world of shopping plazas and industrial forest plantations.

Woodcock may be in trouble.

Every night, Dan McAuley hikes into the woods and raises gossamer nets to catch woodcock on the wing. The U. S. Geological Survey wildlife biologist is outfitting more than 100 birds with tiny radio transmitters in an attempt to study migration.

While McAuley and a group of assistants stand in the moonlight squinting at the nets, woodcock zip across the sky.

“They all just kind of buzz around,” the biologist said, freeing an indignant young female from the net. The bird is a soft motley brown, its feathers designed to disappear into the forest floor, its long skinny beak made for plucking earthworms from the soft soil.

McAuley gently palms the downy bird and places his catch in a mesh bag. Typically, he would tuck the bag in his pocket, zip it shut and move on to the next net, the bird snug in his fleece jacket.

Woodcock are about the size of a robin, with a wobbly flight pattern that birders describe as erratic. Yet each fall, the birds travel more than 1,000 miles from their summer nesting grounds in Maine to winter habitats in Florida and Georgia.

Woodcock fly one of the toughest migration routes in America, said Brad Allen, a wildlife biologist with the Department of Inland Fisheries and Wildlife,

“To get down there, they’ve got to fly through New York City,” Allen said. “The hazards of migration for a little bird like that are incredible.”

McAuley has studied woodcock for more than 30 years. The biologist believes that urban sprawl has destroyed woodcock habitat along their migration route, resulting in high mortality rates.

“We’ll be able to tease out some of the puzzles,” McAuley said. “It’s all guesstimates.”

Woodcock are a riddle to biologists, who struggle to understand how the birds survived before large-scale human habitation of the East coast. The birds require early successional forest habitat with swift-growing, but commercially undesirable trees like aspen and birch.

“The only way to produce this type of forest is to cut it or to burn it,” McAuley said.

Woodcock also use newly cleared land for evening roosting and spring courtship dances. Because the woodcock has many predators, the bird rarely travels more than a mile between the grass where it roosts at night and the wooded area where it feeds during the day.

“They don’t move around a whole lot if they don’t have to,” McAuley said.

Some biologists theorize that woodcock are closely related to sandpipers, and they developed their unique lifestyle fairly recently to take advantage of a new habitat created by European settlers. Others believe that small populations of woodcock have always survived by migrating from place to place as fires and other natural disturbances created clearings.

Either way, woodcock cannot return to their old survival strategies.

Thirty years ago, tremendous clear-cuts were made in Maine, partially in response to the spruce budworm epidemic that killed much of the Maine forest. Woodcock populations boomed.

Today, as forest practices change, Maine’s landscape is becoming a mix of older stands owned by small private woodlot owners, and plantation-style softwood stands planted by industrial foresters. Herbiciding of clear-cut land may also impede the growth of woodcock habitat.

“Woodcock don’t like big trees, and the habitat in Maine is going by,” Allen said.

In Massachusetts and New Jersey, where woodcock need habitat for resting and feeding along the migration route, the situation is even more dire. Though parks and backyards offer shelter for some migratory birds, woodcock need the scrubby, unattractive landscape of a young forest.

“A lot of that habitat has been converted into housing developments,” McAuley said. “That shrubby stuff, for a lot of people – especially urban people – is just nasty stuff they don’t want to have to walk through.”

In Washington County, biologists are working to create woodcock habitat. Every five years, the Moosehorn National Wildlife Refuge in Baring clear-cuts a portion of its land. Older areas are burned to create clearings.

The intensive management has resulted in one of the only woodcock populations in New England that is not in decline.

Maurry Mills, a wildlife biologist who has worked at Moosehorn for 17 years, believes that increasing the number of young woodcock that survive to make their first migration from Maine can help the species regionally.

“By increasing the nesting population, we can make a difference,” he said.

When Moosehorn was created in 1937, the interest in woodcock came primarily from sportsmen. Woodcock are still a legal game bird, with an October season, though interest has dwindled to a small group of devotees who hunt the swift birds with dogs.

Since the 1970s, the woodcock hunting season has been reduced from 65 to 30 days, and the daily bag limit has been reduced from five to three birds, but to no avail. Populations have continued to decline.

“It’s a habitat issue, not a hunting issue,” Allen said.

Moosehorn has published a guide to managing land for woodcock in hopes of attracting private landowners to the birds’ cause.

Engaging industrial forestry companies in boosting marginal woodcock habitat might be the key to the birds’ survival, biologists said.

“As long as the habitat is there, they’ll use it,” Mills said.