Feather damage of long tails in Barn Swallows Hirundo rustica.

Abstract

Extravagant tails of many male birds are morphological structures affected by both natural and sexual selection. Elongated tail feathers may be more vulnerable to damage than feathers of short length. Feather breakage maythus act as a constraint on the evolution of elongated tails, regardless of mode of selection. Feather damage can affect flight performance by producing an asymmetric tail shape that may reduce manoeuvrability and agility Furthermore, feather asymmetry can reduce male mating success. We studied differences in tail damage in relation to tail length in Barn Swallows Hirundo rustica from two populations. Damaged tail feathers were most common in individuals with the longest tails in both populations.