Birds of a Feather: What Songbird Feathers Tell Glacier's Scientists

A cedar waxwing (Bombycilla cedrorum) inspected by a wildlife biologist. NPS.

One bird at a time

By examining birds one at a time, scientists can see the health of a whole species. MAPS — Monitoring Avian Productivity and Survivorship — is a continuing research program that monitors songbird populations and the factors behind them. By handling each bird, researchers can tell its species, age and sex, and follow changes in population trends. The program has about 300 active stations in Mexico, Canada and the United States, and its data inform conservation. In Glacier National Park, MAPS is funded by the Glacier Conservancy.

Reading a wing

A bird's plumage — the bright males, the often drabber females — is part of its survival, and it tells trained researchers a great deal. Close inspection of feathers reveals a bird's condition, and the wings say the most.

Like a hand fan, a bird's wing feathers overlap in three sections: small, densely packed feathers near the top of the wing where the bones lie, and longer feathers below them, almost translucent in the morning light of a survey day. As a handler gently unfolds the right wing, they look for pin feathers emerging and worn, chipped feathers ready to shed.

A pin feather — a new feather, encased in a keratin sheath as it grows. NPS.

Shedding old feathers and growing new ones is molting, and it costs a bird much energy. Most species do one complete molt a year, usually after nesting in late summer. Some also do a partial molt in early spring to put on brighter breeding plumage, and a bird that loses feathers by accident can do an adventitious molt to replace them. These patterns — nearly unique to each species — reveal a bird's age and breeding status. During its brief stop at a MAPS station, each bird's age, reproductive status and molt are recorded, building a picture of how the species is surviving and reproducing on its breeding, molting or wintering grounds.

When feathers nearly doomed birds

The snowy egret (Egretta thula) was hunted relentlessly for its plumes; in six months of 1911, nearly 130,000 egrets were killed. U.S. Fish and Wildlife Service.

In the 1800s, feathered hats became the fashion for American women, and millions of birds were killed — plumes, and sometimes whole birds, worn on hats. Before they could even vote, a group of women campaigned against feathers in fashion. Their work led to landmark laws that framed the Migratory Bird Treaty Act of 1918, which outlawed selling migratory birds, ended commercial plume hunting, and put plumed hats out of style by the end of World War I. A bird conservation movement had begun.

The songbirds' decline

Even so, North American bird populations have fallen by nearly 3 billion birds over the last 50 years, as temperatures, habitat loss and window collisions have risen. Raptors, woodpeckers and waterfowl are recovering thanks to conservationists, researchers and hunters, but songbirds have not been so lucky: once-common birds have suffered most. More than 2.5 billion, or 90%, of the birds lost come from 12 families, including sparrows, blackbirds, warblers and finches.

A bird released after processing at a MAPS station. NPS.

Birds and their feathers matter to cultures around the world, to ecosystems, and to the idea of wildness. Monitoring and research — and a community working together — are key to helping them recover in a fast-changing world.

More on MAPS in Glacier: The Buzz of Bird Banding and Taking Flight, which notes that more than 1,200 MAPS stations have collected more than 2.5 million capture records.

Sources

Based on "Birds of a Feather," Glacier National Park, National Park Service; a work of the United States government in the public domain.