Male swamp sparrows adjust vocals in hostile situations

January 10th, 2009 - 12:29 pm ICT by ANI  

Washington, January 10 (ANI): A study on sparrows has revealed that the male Swamp Sparrow adjusts its vocal when faced with a hostile situation.
Adrienne DuBois, a graduate student at the University of Miami (UM) College of Arts and Sciences Department of Biology, says that the birds ability to emit such songs as are physically difficult to produce during hostile situations suggests that it uses sophisticated vocal performances as signals in aggressive communication. In a research paper published online in Biology Letters, the studys authors say that it contributes to the current understanding of how animals use signals to communicate. DuBois revealed that the study was aimed at determining whether vocal performance is used as a signal in aggressive interactions between male songbirds.
The researcher said that the study showed that, when challenged, the male Swamp Sparrow escalates its vocal performance by increasing the frequency range and the speed of its song.
“Vocal performance was thought to be a static characteristicset once a song is learned. Our results are the first to show that songbirds can modulate vocal performance, when it is important to do so,” DuBois said.
While it has theoretically been thought that only males with better genes, or those in better condition, should be able to produce high performance songs, the current study has shown that males are able to increase their vocal performance when challenged by a competitor.
“Even in the case of signals whose properties are physically constrained to reflect an individual’’s abilities, animals exaggerate their signals as much as they can, during critical situations,” said Bill Searcy, Maytag professor of Ornithology in the UM College of Arts and Science and co-author of the study.
The slow trills of the Swamp Sparrows can be heard during spring and summer across the Eastern and Central North American wetlands.
The small songbird with a grey face and reddish wings defends his territory and attracts a mate usually by singing from a raised perch in a brushy swamp.
Steve Nowicki, Duke University professor, dean of Undergraduate Education and co-author of the study, said that the new findings could be extrapolated to other areas of study, including the evolution of communication, and animal cognition.
“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,” said Nowicki. (ANI)

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