Baltimore oriole's decline a mystery to scientists


WASHINGTON -- The fortunes of the Maryland state bird are on a steady decline.

About 24 percent fewer Baltimore orioles are in Maryland today than there were 30 years ago, when accurate records started being kept, and the rate of decline throughout the region is accelerating, government data reveal.

"It's not at the point where it's going to be listed as endangered, but if this trend were to continue over a period of time, it could," said Bruce Peterjohn, the coordinator of the Breeding Bird Survey. The survey is coordinated each year from the Patuxent Environmental Science Center in Laurel.

The average annual rate of decline in Maryland from 1966 to 1994 was 0.8 percent.

The rate of decline has been sharpest recently. In Maryland, the average annual rate of decline has been 1.9 percent since 1980 -- more than six times the rate of 0.3 percent from 1966 to 1979.

No one knows why the Baltimore oriole population is declining, said Doug Gross, a biologist for Ecology III, an environmental consulting firm.

Scientists said they have suspicions. For instance, the bird's habitat is slowly disappearing.

Baltimore orioles prefer to hang their baglike nests from shade trees, particularly elms. Dutch elm disease, a fungus infection, has destroyed elms, said Douglas Gill, a University of Maryland zoology professor.

The bird loses breeding grounds when rural areas are developed, Mr. Gross said.

Pub Date: 4/21/96

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