The falloff in songbird populations and woodpeckers also remains an annual concern.

Many ornithologists maintain that collisions are a leading cause of decline in songbird populations, second only to habitat loss.

But a new study suggests that United States land development may be a much more potent factor in slashing songbird populations.

However, there is a lack of qualitative evidence that grey squirrels are actually having a significant impact on songbird populations.

The destruction of the earth's habitat by mankind has already had sinister results, Mr. Eldredge maintains, of which the waning of North America's songbird population is one.

Many studies, mostly short-term, failed to find an effect on songbird populations caused by predatory birds such as Eurasian Sparrowhawks.

The overpopulation of crows is also having a negative effect on the dwindling songbird population in what's left of its habitat in suburbia.

"They're basically crowding out the songbird populations," he said.

Providing such food and shelter is increasingly important because migratory songbird populations in the Western Hemisphere have plummeted, some as much as 90 percent, over the last 20 years.

The ominous decline in songbird populations over the last 30 years makes the refuge all the more critical as a last bastion on the Atlantic Flyway.