Behavioral Ecology Advance Access originally published online on February 24, 2008
Behavioral Ecology 2008 19(3):517-524; doi:10.1093/beheco/arn015
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Plumage color and reproduction in the red-backed fairy-wren: Why be a dull breeder?
a School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164-4236, USA b Center for Tropical Research, Institute of the Environment, University of California at Los Angeles, La Kretz Hall, Suite 300, Box 951496, Los Angeles, CA 90095, USA
Address correspondence to M.S. Webster. E-mail: mwebster{at}wsu.edu.
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Abstract |
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Males of many species can breed in distinct alternative phenotypes; for example, in many birds some males breed in dull plumage while others breed in bright plumage. Because females often appear to prefer brighter males, it is unclear why some males breed in dull plumage. Males in dull plumage might enjoy enhanced within-pair reproductive success if they can gain access to better breeding territories, or they might have relatively high extrapair reproductive success if they are better able to intrude on the territories of other males. To test these possibilities, we examined the reproductive consequences of plumage color in the red-backed fairy-wren (Malurus melanocephalus), a species in which males can breed in either bright plumage or dull plumage or serve as nonbreeding auxiliaries. Male plumage color was distributed bimodally and was loosely associated with age, such that some males molted into bright plumage a year or more earlier than others. Both male phenotypes were cuckolded at similar rates, but bright males sired significantly more extrapair young than did dull males, and this effect was independent of age. Thus, 1-year-old males who bred in dull plumage had low seasonal reproductive success compared with same-aged males who bred in bright plumage. These results suggest that males may not reap any fitness benefits by breeding in dull coloration, compared with breeding in bright plumage, but rather may be constrained to breed in suboptimal plumage by the timing of plumage acquisition.
Key words: alternative breeding strategies, delayed plumage maturation, extrapair paternity, fairy-wren, Malurus melanocephalus, plumage coloration.
Received 9 October 2007; revised 14 December 2007; accepted 17 December 2007.