title: Phenotype-limited distributions: short-billed birds move away during times that prey bury deeply.
abstract: In our seasonal world, animals face a variety of environmental conditions in the course of the year. To cope with such seasonality, animals may be phenotypically flexible, but some phenotypic traits are fixed. If fixed phenotypic traits are functionally linked to resource use, then animals should redistribute in response to seasonally changing resources, leading to a 'phenotype-limited' distribution. Here, we examine this possibility for a shorebird, the bar-tailed godwit (Limosa lapponica; a long-billed and sexually dimorphic shorebird), that has to reach buried prey with a probing bill of fixed length. The main prey of female bar-tailed godwits is buried deeper in winter than in summer. Using sightings of individually marked females, we found that in winter only longer-billed individuals remained in the Dutch Wadden Sea, while the shorter-billed individuals moved away to an estuary with a more benign climate such as the Wash. Although longer-billed individuals have the widest range of options in winter and could therefore be selected for, counterselection may occur during the breeding season on the tundra, where surface-living prey may be captured more easily with shorter bills. Phenotype-limited distributions could be a widespread phenomenon and, when associated with assortative migration and mating, it may act as a precursor of phenotypic evolution.
authors.affiliation: Department of Marine Ecology , NIOZ Royal Netherlands Institute for Sea Research , PO Box 59, 1790 AB Den Burg, Texel, The Netherlands.
authors.forename: Sjoerd
authors.initials: S
authors.lastname: Duijns
authors.affiliation: Department of Marine Ecology , NIOZ Royal Netherlands Institute for Sea Research , PO Box 59, 1790 AB Den Burg, Texel, The Netherlands.
authors.forename: Jan A
authors.initials: JA
authors.lastname: van Gils
authors.affiliation: Wash Wader Ringing Group , The Old School House , Rhoon Road, Terrington St Clement, Norfolk PE34 4H, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Smart
authors.affiliation: Department of Marine Ecology , NIOZ Royal Netherlands Institute for Sea Research , PO Box 59, 1790 AB Den Burg, Texel, The Netherlands ; Chair in Global Flyway Ecology, Groningen Institute for Evolutionary Life Sciences (GELIFES) , University of Groningen , PO Box 11103, 9700 CC Groningen, The Netherlands.
authors.forename: Theunis
authors.initials: T
authors.lastname: Piersma
keywords: Limosa lapponica; body size; distribution; food availability; morphology; resource use