Swamp Sparrows Change Their Tune for Competitors

Ornithologist Adrienne DuBois, a graduate student from the University of Miami, has discovered that male swamp sparrows modify their song when competing males are nearby. The song of a male swamp sparrow is a slow trill of two or more pitches.

Listen to the swamp sparrow's song:

Previously, scientists thought that once the swamp sparrow learned its song, it did not modify it—the swamp sparrow simply sang the same tune repeatedly. But DuBois' research shows that swamp sparrows do not sing the same song over and over again. Instead, when competitors are in range, they modify their song—increasing the frequency range and the speed at which they sing.

The results from DuBois' research have implications outside of the field of ornithology. Birdsong provides scientists with insight into the evolution of communication. Steve Nowicki of Duke University, a co-author of DuBois' study, explains what birdsong reveals about communication in animals:

"By understanding what animals do in their natural environment, we get a glimpse of what their brains can do. In a broader sense, we can make assumptions about the way the animal brain develops to support a complex communication system."

Swamp sparrows (Melospiza georgiana) are small songbirds that inhabit wetlands throughout eastern and central North America. During the summer months, swamp sparrows inhabit a range that extends from Canada's Yukon Territory eastward to Labrador and southward to Nebraska, the upper midwest, and coastal New England. Their winter range extends from Southern New England to Florida, the midwest, and down into Texas and Mexico. Swam sparrows inhabit a variety of freshwater and tidal wetlands including marshes, meadows, swamps, and bogs.

Find out more: DuBois A, Nowicki S, Searcy W. 2008. Swamp Sparrows Modulate Vocal Performance in an Aggressive Context. Biology Letters.

Photo © Robert Lachlan.