Behavioral Ecology Advance Access originally published online on March 8, 2007
Behavioral Ecology 2007 18(3):563-570; doi:10.1093/beheco/arm015
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Breeding rate is associated with pheomelanism in male and with eumelanism in female barn owls
a Department of Ecology and Evolution, University of Lausanne, Biology Building, CH-1015 Lausanne, Switzerland b Avian Demography Unit, Department of Statistical Sciences, University of Cape Town, Rondebosch 7701, South Africa
Address correspondence to A. Roulin. E-mail: alexandre.roulin{at}unil.ch.
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Abstract |
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Melanin-based coloration exists in 2 types: black eumelanism and reddish-brown pheomelanism, which both have a strong heritable component. To test whether these 2 types of melanism are associated with alternative adaptations, we carried out a correlative study over 8 years and an experiment in a Swiss population of barn owls, Tyto alba. This species varies in coloration from reddish-brown to white and from lightly to heavily marked with black spots. Based on the fact that plumage coloration and spottiness are male- and female-specific secondary sexual characters, respectively, we examined whether the probability of breeding is associated with the degree of pheomelanism in males and of eumelanism in females. In males, recruited nestlings were significantly less reddish-brown than their nonrecruited nest mates. In females, individuals displaying larger black spots started to breed at a younger age and had a higher survival, and females with experimentally reduced plumage spottiness bred less often than control females. Therefore, in the barn owl, the degree of male pheomelanism is associated with the probability of being recruited in the local population, whereas the degree of female eumelanism correlates with age at sexual maturity, survival probability, and also the probability of skipping reproduction.
Key words: color polymorphism, female ornament, melanin, sexual maturity, survival, Tyto alba.
Received 24 March 2006; revised 1 February 2007; accepted 2 February 2007.