The role of pigment based plumage traits in resolving group conflicts (#815)
The role of melanin plumage, or ‘badges of status’, in male-male competition has been well-studied. In contrast, carotenoid based plumage has largely only been examined in the context of female mate choice. Recent work has shown that carotenoid signals can also function in male-male competition, though the relative importance of the two types of signals is currently unclear. Here, we examine the relationships between colouration, dominance and aggression in the crimson finch (Neochmia phaeton), a species where males have both conspicuous red carotenoid plumage and a melanin black ‘badge’. We examined the importance of carotenoid and melanin based signals in staged dyadic contest in captivity. We found that carotenoid coloration was positively related to the probability of winning a contest, while the size of the melanin plumage patch was not related to contest outcome. When the carotenoid signal was masked (plumage darkened) we found that the manipulated plumage colour was not related to winning, while the underlying natural plumage colour was still important, but birds with more carotenoids were now more likely to lose. Nevertheless the number of interactions required to determine dominance increased considerably. These results suggest that carotenoids are an important signal in male-male contests but that they are used in conjunction with other factors such as self-assessment and body condition. While the black melanin patch, traditionally viewed as a signal of male dominance, was not found to be important in this context.