Bird Climate and Song Related
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Bird Climate and Song Related

July 19, 2010
Male and female tropical mocking bird in Villa de Leyva, Colombia, South America.

More about this Image A team of researchers from the National Evolutionary Synthesis Center (NESCent), the Cornell Lab of Ornithology and McGill University studied the relationship between mockingbird's habitats and their songs. The researchers found that birds which live in more variable climates have more complex tunes. "As environments become more variable or unpredictable, song displays become more elaborate," said Carlos Botero, a postdoctoral researcher at NESCent in Durham, N.C.

In climates with unpredictable weather patterns, survival and reproduction are more complicated because species cant depend on when food will be available or for how long. Therefore, females must be choosey when selecting a mate.

The main reason male mockingbirds sing is to attract a mate; therefore, the better the singing skills, the greater the chances are of finding one. For a female, the complexity of a song, how many song types a male bird may know and the difficulty of the songs are all indicators of a quality mate. In addition, says Botero, "Males that sing more complex songs tend to carry fewer parasites, and have offspring that are more likely to survive."

Songbirds are not born with their music skills--they learn them over time. Botero and his colleagues suspect that, since birdsong is a learned behavior, a male's ability to learn a complex song may also indicate greater intelligence--another quality that may attract females. An intelligent male is more likely to know how to cope in an uncertain environment. For example, if food is scarce--in a harsh winter for example--an intelligent male may invent or learn new foraging techniques to survive, whereas a less-intelligent male may only know one way to forage. "The more intelligent you are, the more resourceful you are, and the more curve balls you're able to handle," says Botero.

To try and determine if there is a connection between the mockingbird's climate and their songs, Botero studied sound archives from around the world and traveled throughout the Southern Hemisphere, where he recorded wild bird songs in all types of habitats, including desert, jungle, scree and scrub in search of mockingbird songs.

After collecting his data, Botero used computer programs to convert the sound recording--100 tracks from 29 species of mockingbirds--into a sonogram or sound graph, a complex pattern of lines and streaks that allows scientists to see and visually analyze sound. Afterwards, each snippet of song was analyzed and then compared with temperature and precipitation records. Botero and his colleagues found that species that live in more variable and unpredictable climates had more elaborate songs displays.

Botero and his colleagues plan on continuing their research to see if such a pattern exists in other animal species. [NESCent is a National Science Foundation (NSF)-funded collaborative research center operated by Duke University, the University of North Carolina at Chapel Hill and North Carolina State University. Research supported by National Science Foundation grant DEB 05-15981.] (Date of Image: 2004-2007)

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