Adventitious molt

Because plumage is a relatively static signal type, birds expressing plumage signals that are thought to honestly signal condition may face a trade-off between timing of signal production and signal quality. For example, signals produced relatively early may be of lower quality because of seasonal constraints such as lower food availability, or may face increased fading or wear of plumage associated with extended duration of signal expression. By comparing feather hue through spectrophotometric analysis of feathers produced during the non-breeding and breeding seasons , I found that red-backed fairywren males that expressed ornamented red/black plumage early (during the non-breeding season) increased plumage hue between these two periods. Spectrophotometry is a tool that allows us to quantify color, so that we can give fairywren back color a specific number instead of likening it to a color in a box of crayons. Fairywrens appeared to increase their signal quality by replacing feathers outside normal molt periods (i.e. adventitious molt). In this way, some male red-backed fairywrens may be able to molt into nuptial plumage in the non-breeding season, and enhance the red hue of their plumage-based sexual signal to a putatively more attractive state at a later date, which is likely to increase access to mates or resources. Adventitious molt is a relatively understudied potential for signal modification outside of the annual molt cycle in birds, and investigating the prevalence of this strategy across species is an interesting avenue for future research.

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