Is male plumage reflectance correlated with paternal care in bluethroats?

Although it is now well established that the conspicuous male plumage colors of many birds have been subject to sexual selection by female choice, it is still debated whether females mate with colorful males to obtain direct or indirect benefits. In species where males provide substantial parental care, females may obtain direct benefits from mating with the males that are best at providing care. The good parent hypothesis suggests that male plumage coloration signals a male’s ability to provide parental care. Alternatively, the differential-allocation hypothesis suggests that colorful males reduce their care in response to increased investment by females mated to attractive males. We tested these hypotheses on the bluethroat (Luscinia s. svecica), a socially monogamous, sexually dichromatic bird, in which males have a colorful throat patch consisting of a structurally derived blue area surrounding a melanin-based chestnut spot. Male plumage coloration was objectively quantified by use of reflectance spectrometry. We found no evidence of a relationship between male coloration of either the blue patch or the chestnut spot and the level of paternal care. Nor were there any correlations between male coloration and body size or body condition. Thus, our study does not support the hypothesis that male coloration signals male parental quality (the good parent hypothesis) or the hypothesis that colorful males reduce their care in response to increased investment by females (the differential-allocation hypothesis). Key words: direct benefits, female choice, Luscinia s. svecica, parental care, plumage coloration, sexual selection, spectral reflectance. [Behav Ecol 12:164–170 (2001)]