Adventitious feather replacement favours a more rapid regeneration of primaries over rectrices in two passerine bird species

Abstract

There is increasing evidence of adaptive preferential investment during moult in those feather tracts that are more advantageous for fitness. In this study, we assessed whether, after the manual removal of two functionally different flight feathers (one primary and one rectrix), birds from two common passerine species (Eurasian Blackcap Sylvia atricapilla and European Robin Erithacus rubecula) favoured the regeneration of primary (supposedly the most functionally important feathers) over rectrix feathers. Our results did not show differences between replaced primary and rectrix feathers in their final length, but demonstrated that the gap left by the loss of the primary feather was filled earlier, suggesting that a rapid repair of the most essential feather tracts is also evolutionarily advantageous during the adventitious replacement of plumage.

Moult in the Loggerhead Shrike Lanius ludovicianus is influenced by sex, latitude and migration

“…In the tail, the central pair of feathers acts as a protective covering for the remaining rectrices. The preformative moult in Loggerhead Shrikes, although not including all flight feathers, ensures those feathers that receive the most wear are renewed, thus maximizing the effectiveness of a moult with minimum investment (Jenni & Winkler 1994, de la Hera et al 2015. The descendant order is thought to provide better protection for growing primaries against upward bending by lift forces during flight compared with the ascendant sequence (Noordhuis 1989in Jenni & Winkler 1994.…”