Alarm call like the whetting of saw blade

BOONSBORO - The high-pitched, staccato mating call of a northern saw-whet owl pierces the night and lures birds into a gossamer net that researchers have strung along the Appalachian Trail.

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The owls -fluffy, brown-and-white raptors about the size of a human fist- are weighed, measured, banded and released to help scientists learn more about their migration patterns.By Thanksgiving, the Department of Natural Resources hopes to have banded and released more than 1,000 saw-whet owls captured while flying from the northern United States and Canada to southern destinations including western Maryland and West Virginia.

The most active of four Maryland banding stations is on Lamb’s Knoll, a 1,758-foot peak atop South Mountain near Boonsboro. Biologists and volunteers have banded as many as 73 owls a night there during the first four weeks of the two-month migration period.

„Three a.m. to dawn, we can get slammed”, said David F. Brinker a DNR ecologist and founder of Project Owlnet. Composed of scientists in 11 Eastern and Midwestern states and Ontario, Canada, the project aims to improve understanding of nocturnal owl migration. „This is a species that for many years people thought was rare, but it was rarely seen”, Brinker said.

In the fall, many northern saw-whet owls migrate hundreds of miles south while others stay within their breeding ranges - patterns that are well documented in some areas but still poorly understood, according to Project Owlnet.

Every four years, an ”irruption”, or sudden population increase, provides opportunities for studying the owls at dozens of banding stations. Brinker said the numbered leg bands include instructions on how to report an owl found dead or alive.

The saw-whet owl is named for its distinctive alarm call, which sounds like the whetting of a saw blade.

To collect birds for banding, researchers use a recording of the owl’s courtship call, a whistled ”hoop” repeated more than once a second, sometimes for several hours without a break.

During the banding season, volunteer Steve Huy, who lives nearby, spends six or seven nights a week at the station. Huy weighs each captured bird by sliding it headfirst into an empty fruit-juice can and then placing the can and owl on a scale. While the bird is immobilized, he uses a pliers-like tool to wrap a metal band around one of its legs. Then he removes the bird from the can, measures its wings and beak and examines it for molting and signs of whether it is well-nourished. (World)