VCU biologist finds evidence of global warming

By Mike Frontiero
VCU School of Education

RICHMOND, Va. – Scientists and politicians have debated the existence of global warming for many years. Now, a biologist at Virginia Commonwealth University contends he has evidence that the earth is indeed getting warming, and he points to the migratory pattern of a little yellow bird due to return to its U.S. breeding grounds in early April.

Charles R. Blem, Ph.D., currently is preparing more than 300 nesting boxes for the return of thousands of Prothonatory Warblers. For the last 16 years, Blem has studied the birds’ migratory patterns and breeding habits in a swampy area of Virginia’s James River. But what started as a basic research study revealed an interesting trend: the bird has returned from its winter home in South America and the Carribean an average of one day earlier every year.

"We started studying Warbler population changes as a part of neotropical migrant bird decline," said Blem. "Only secondarily it turned out the numbers were changing with time and reflected a change in climate."

Blem is an ornithologist and ecologist in VCU’s Department of Biology. According to Blem, the temperature of the nesting area has increased one degree since his study began. The warmer it gets, he says, the sooner the birds return.

"I predict that if this keeps up, this bird will become a resident species of North America entirely," said Blem.

Along with his team of volunteers and graduate students, Blem has amassed one of the most comprehensive data collections on this particular bird.

"We know who their mother was. We know who their grandmother was in some cases. We know how many eggs they laid so we can get a handle on long-term change," said Blem.

The Prothonatory Warbler, also known as the Golden Swamp Warbler, is a striking bright orange-yellow color and measures about five inches long. It flies only at night during migration and breeds throughout the southeastern United States and in southern Canada. Destruction and degradation of breeding and wintering areas and competition from other birds threaten the warbler’s population, which has declined in recent years. Blem says nesting boxes, which provide safe shelter from weather and predators, are helping to reverse that trend.

Last year, the warblers returned to Central Virginia on April 6. Barring a cold spell, Blem predicts the birds will be back in the United States around April 5 this year.