title: Resistance of flight feathers to mechanical fatigue covaries with moult strategy in two warbler species.
abstract: Flight feather moult in small passerines is realized in several ways. Some species moult once after breeding or once on their wintering grounds; others even moult twice. The adaptive significance of this diversity is still largely unknown. We compared the resistance to mechanical fatigue of flight feathers from the chiffchaff Phylloscopus collybita, a migratory species moulting once on its breeding grounds, with feathers from the willow warbler Phylloscopus trochilus, a migratory species moulting in both its breeding and wintering grounds. We found that flight feathers of willow warblers, which have a shaft with a comparatively large diameter, become fatigued much faster than feathers of chiffchaffs under an artificial cyclic bending regime. We propose that willow warblers may strengthen their flight feathers by increasing the diameter of the shaft, which may lead to a more rapid accumulation of damage in willow warblers than in chiffchaffs.
authors.affiliation: Department of Animal Ecology, Ecology Building, Lund University, Sölvegatan 37, S-223 62 Lund, Sweden. thomas.weber@zooekol.lu.se
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Weber
authors.forename: Johan
authors.initials: J
authors.lastname: Borgudd
authors.forename: Anders
authors.initials: A
authors.lastname: Hedenström
authors.forename: Kent
authors.initials: K
authors.lastname: Persson
authors.forename: Göran
authors.initials: G
authors.lastname: Sandberg
mesh_terms: D025041:Animal Migration; D000818:Animals; D001696:Biomechanical Phenomena / Q000295:instrumentation; D005241:Feathers / Q000033:anatomy & histology / Q000502:physiology*; D005426:Flight, Animal / Q000502:physiology*; D018978:Molting / Q000502:physiology*; D020308:Songbirds / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D013045:Species Specificity