Behavioral Ecology Advance Access published online on June 15, 2009
Behavioral Ecology, doi:10.1093/beheco/arp079
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Song types, song performance, and the use of repertoires in dark-eyed juncos (Junco hyemalis)
a Department of Zoology, University of Melbourne, Victoria 3010, Australia b Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405, USA c Department of Ecology and Evolution, University of Chicago, 1101 East 57th Street, Chicago, IL 60637, USA
Address correspondence to G.C. Cardoso. E-mail: gcardoso{at}unimelb.edu.au.
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Abstract |
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Song performance encompasses the idea of how physiologically demanding different songs are to sing, and this is thought to reflect the singing ability of individual birds. In the dark-eyed junco (Junco hyemalis), each male has a repertoire of song types, some of which are shared with other males in the population. We used 4 measures of performance, based on trade-offs between song traits, to test if song performance is consistent among the song types making up the repertoire of individual males. We also tested if song types differ consistently in performance regardless of which males sing them. We found low but significant correlations of performance measures among the song types of individual males. This contrasts with highly consistent differences in performance among song types, regardless of which males sing them. We conclude that performance of single song types, as evaluated by trade-off–based measures of performance, gives little information about male singing ability. As song types differ in performance, we asked if males use the song types in their repertoires differently. We found that juncos use higher performance song types during bouts of more motivated singing, as evaluated by the length of songs, suggesting that song types may be preferentially used in different contexts depending on their performance.
Key words: bird song, dark-eyed junco, Junco hyemalis, song performance, song repertoires.
Received 30 July 2008; revised 8 December 2008; accepted 13 May 2009.