Follow that bird: Bedford Audubon tracks thrushes with GPS

• Wood thrushes are disappearing from eastern forests.
• The birds fly to Central America each fall and return in the spring.
• To understand why their numbers are dropping, scientists attached tiny GPS devices to some males.
• Researchers hope to recapture some of the same birds next spring and download their data.

Scientists want to figure out why wood thrushes, small reddish-brown birds known for their flute-like sound, are disappearing from forests near you.

To learn more, they're using the same technology you might be employing to find the best route home through traffic.

More than three dozen male thrushes, including some in northern Westchester, were captured in recent weeks and fitted with a tiny GPS tracking device.

Wood thrushes raise their families here each spring before returning to Central America each fall. As their numbers continue to plummet, scientists are trying to determine where they are most at risk: on their breeding grounds, their migratory routes or their overwintering grounds. Losing them would be a conservation failure, creating a diversity gap in our forests and silencing their melodious song.

Habitat loss both here and in Central America may be exposing the birds to more predators and depriving them of high-quality food, experts say.

Researchers hope to recapture some of the same birds next June and download data from the devices, said Janelle Robbins, executive director of the Bedford Audubon Society. Males tend to return to the same areas each spring to breed, she said.

By the numbers

More than 50 percent: How much wood thrush numbers have fallen in the past 40 years

44: The number of tracking devices attached to birds here and in North Carolina

22: The number of GPS devices deployed at Audubon and The Nature Conservancy properties in North Salem, Lewisboro and Bedford

50: The number of times the devices will collect location data as the birds migrate in the fall, overwinter and return next spring. The information will be downloaded when a thrush is caught again

$465: The cost of each device

1 gram: The weight of one tracking device

40-50 grams: The weight of an unladen thrush