Behavioural differences between ornamented and unornamented male Red-backed Fairywrens (Malurus melanocephalus) in the nonbreeding season

Abstract

ABSTRACT During the breeding season, male Red-backed Fairywrens (Malurus melanocephalus) can exhibit ornamented (red-black) or unornamented (brown, resembling females and juveniles) plumage. These distinct plumage types represent alternative reproductive tactics and are associated with behavioural differences during the breeding season. However, we lack an understanding of whether and how these plumage types may be associated with behavioural differences during non-reproductive parts of the year. To fill this knowledge gap, we carried out behavioural observations during the nonbreeding season across three years. We hypothesised that ornamented plumage remains associated with mate attraction behaviours outside of the breeding season. We examined the investment of ornamented, moulting, and unornamented males in social behaviours and found that the three plumage types were largely similar in their behaviour except ornamented males courted and, to a lesser extent, allopreened at higher rates than unornamented males. Since concurrent work in the same study population demonstrates increased extra-pair fitness for males who moult into ornamented plumage early, we speculate that ornamentation and courtship behaviour may serve a mate attraction function outside of the breeding season. We argue that future studies should consider individual-level behavioural monitoring throughout the annual cycle to better quantify the complex selection pressures that lead to the coevolution of plumage moult and alternative reproductive tactics in this system.