Taking fast count before trill is gone

Migration: Biologists keep track of songbirds reaching Maryland.

May 12, 2002|By Heather Dewar | Heather Dewar,SUN NATIONAL STAFF

Jewel-bright songbirds are nest-building now along the Patuxent River, at the end of their long migration. At Jug Bay Wetlands Sanctuary in Lothian, bird banders see more than a dozen of the 69 species that passed through the Texas woods this month.

On a still, bright morning last week, the birders were surrounded by a tumult of birdsong. Elizabeth Sellers of Lorton, Va., singled out the songs of a half-dozen long-distance travelers, including a red-eyed vireo, whose trill is commonly translated as "Where are you? Here I am," and an indigo bunting insistently calling "Fire, fire! Where? Where?"

Sellers, 10 other interns and two instructors are working on a long-term, continent-wide project, the Monitoring Avian Productivity and Survivorship (MAPS) study, run by the Institute for Bird Populations in Point Reyes, Calif.

Every summer across the country, biologists and volunteers study breeding birds at 500 sites. MAPS trainer Amy McAndrews said the resulting data show which birds are thriving and which are in trouble in different regions, and help land managers protect nesting and feeding grounds.

This month, McAndrews and ornithologist Jorge Montejo were training a dozen students at Mad Island on Texas' Matagorda Bay, where the northward migration was in full swing. Montejo is the biologist at a nature reserve in Chiapas, Mexico, where many songbirds spend the winter. His students came mostly from the birds' far-flung summer homes, in Canada and the northern United States.

Last week another group of trainees was at Jug Bay, catching the birds as they move north or settle in for the summer.

At dawn the banders set up fine-meshed, nearly invisible "mist nets" in the woods and near the river shore. Unwary warblers, buntings and orioles by the dozens fly into the nets.

The volunteers patiently untangle them. They attach numbered steel bands to the birds' legs, take detailed notes on their age, sex and condition, and dunk them head-first into a film canister or piece of plastic pipe, which holds them still enough for weighing. Then they open their hands and watch the bright creatures vanish.

This fall, veteran ornithologist Danny Bystrak will conduct a similar study of southbound migrants. He thinks the results will show that riverfront thickets at Jug Bay and elsewhere along the migration route provide essential food and shelter for the journey.

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