TU professor discovers natural selection in cliff swallows

Monday, March 18, 2013

Study shows birds can adapt to high-traffic, urban environments

Birds appear to have the ability to rapidly evolve in order to avoid new urban threats such as cars, according to new research conducted by University of Tulsa Biological Science Professor Charles R. Brown. His findings are published in the March 18 edition of the science journal Current Biology.

Charles BrownBrown, his colleague Mary Bomberger Brown at the University of Nebraska-Lincoln, and many undergraduate assistants have studied the group living patterns of cliff swallows in western Nebraska for three decades. They have collected hundreds of dead cliff swallows from roadways, railroad tracks and other nesting areas, and recent analysis of these specimens revealed a surprising trend.

“There were fewer road kills, and the birds found along highways had longer wing spans,” Brown said. “I wanted to know if there was selection for particular characteristics in those dead birds.”

Brown’s team began a retrospective analysis, measuring the specimens in his 30-year collection. The results suggested cliff swallows were undergoing morphological changes through natural selection.

“The study shows evolution can work on very short time scales (30 years), and certain traits in birds can change,” Brown said. “These animals have adapted to their high-traffic, urban environments, perhaps in part with shorter wing spans that may provide greater maneuverability and a better chance of avoiding vehicles.”

Brown said the findings suggest cliff swallows also have the ability to learn from other members of their colony; when they see other birds succumb to traffic on highways or have a close encounter with a car, they can learn to avoid the vehicles for survival.

“It was a fortuitous discovery, but biologists may find similar examples of how animals adapt to human landscapes and land use,” Brown said.

Gail Banzet