Behavioral Ecology Advance Access originally published online on February 7, 2008
Behavioral Ecology 2008 19(3):508-516; doi:10.1093/beheco/arm159
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The effects of delayed plumage maturation on aggression and survival in male red-backed fairy-wrens
a 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 b Smithsonian Migratory Bird Center, National Zoological Park, PO Box 37012, MRC 5503, Washington, DC 20013, USA c School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, WA 99164-4236, USA
Address correspondence to J. Karubian. E-mail: jordank{at}ucla.edu.
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Abstract |
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The occurrence of multiple phenotypes within a sex of a single species has long puzzled behavioral ecologists. Male red-backed fairy-wrens Malurus melanocephalus exhibit 3 behaviorally distinct types in their first breeding season: breed in bright nuptial plumage, breed in dull plumage, or remain as an unpaired auxiliary (helper) with dull plumage. The retention of dull plumage by auxiliaries and dull breeders is an example of delayed plumage maturation (DPM), a widespread phenomenon in birds whose costs and benefits are not well understood. At a mechanistic level, DPM might allow dull males either to deceptively mimic females (female mimicry hypothesis) or to honestly signal their subordinate status (status-signaling hypothesis). DPM might function via either mechanism to provide ultimate benefits relative to developing nuptial plumage by increasing reproductive success, survival, or both. In this study, we tested the hypothesis that DPM is related to increased male survival in the red-backed fairy-wren via either female mimicry or status signaling. Aviary-based experiments revealed that dull males were perceived as male, which is consistent with the status-signaling hypothesis but contradicts the female mimicry hypothesis. Further aviary and field-based experiments also revealed that dull males were socially subordinate to bright males and received less aggression than bright males, further evidence for status signaling. However, male survival was not related to plumage coloration or breeding status. These findings indicate that male plumage coloration signals social status but that dull plumage does not afford a net survival advantage, perhaps because plumage color is a conditional strategy.
Key words: alternative breeding strategies, delayed plumage maturation, fairy-wren, Malurus melanocephalus, plumage coloration, survival.
Received 12 June 2007; revised 17 December 2007; accepted 17 December 2007.