Discrimination between host songs by brood parasitic brown-headed cowbirds ( Molothrus ater) |
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Authors: | Hauber Mark E Pearson Heather E Reh Andrea Merges Angela |
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Institution: | (1) Field of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA,;(2) Present address: Department of Integrative Biology, Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720-3140, USA, e-mail: hauberm@socrates.berkeley.edu, Tel.: +1-607-2620044, Fax: +1-510-6438238, |
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Abstract: | Songbirds can learn both to produce and to discriminate between different classes of acoustic stimuli. Varying levels of
auditory discrimination may improve the fitness of individuals in certain ecological and social contexts and, thus, selection
is expected to mold the cognitive abilities of different species according to the potential benefits of acoustic processing.
Although fine-scale auditory discrimination of conspecific songs and calls has been frequently reported for brood parasitic
brown-headed cowbirds (Molothrus ater), it remains unclear why and how they perceive differently the songs of their many host species. Using habituation-dishabituation
paradigms and measuring behavioral and physiological (heart-rate) responses, we found that captive female cowbirds consistently
discriminated between songs of two host species, the song sparrow (Melospiza melodia) and the red-winged blackbird (Agelaius phoeniceus). Playback experiments with stimuli composed of con-specific followed by heterospecific vocalizations in the field also demonstrated
discrimination between these heterospecific songs even though cowbirds were not attracted to playbacks of either host species'
songs alone. Our results do not directly support a nest-searching function of heterospecific song discrimination by cowbirds
and are most consistent with a function of the parasites' avoidance of attacks by their agressive hosts. These data demonstrate
discrimination between heterospecific vocalizations by brown-headed cowbirds and add a novel dimension to the already expansive
auditory perceptual abilities of brood parasitic species and other songbirds.
Electronic Publication |
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Keywords: | Brood parasitism Discrimination Host– parasite interactions Species recognition systems |
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