AVIS-IBIS

Birds of Indian Subcontinent

Wing shape variation of Finnish and Central European Willow Warblers Phylloscopus trochilus and Chiffchaffs P. collybita

Publication Type:Journal Article
Year of Publication:1985
Authors:TlAINEN, JUHA, Hanski, IK
Journal:Ibis
Volume:127
Issue:3
Date Published:1985
ISBN Number:1474-919X
Keywords:Acredula, Finland, Germany, Phylloscopidae, Phylloscopus, Phylloscopus collybita, Phylloscopus trochilus, Trochilus
Abstract:Wing shape variation of European Willow Warblers Phylloscopus trochilus and Chiffchaffs P. collybita was studied using indices calculated from wing formulae. Our data were from free-living local populations of P. t. acredula and P. c. abietinus from southern Finland, and P. t. trochilus and P. c. collybita from southwestern Germany. There were no significant shape differences between the subspecies of the Willow Warbler in which sexual dimorphism was pronounced. The subspecies of the Chiffchaff were significantly different while the sexes were not. There were also significant differences between adult and immature individuals in the autumn. The intrapopulation variation must be considered in attempts to recognize different subspecies or populations in data on birds caught during migration. In the Willow Warbler at least, the difference between age-groups was larger in males than in females. If the change in wing formula due to the complete pre-nuptial moult is similar in both sexes, juvenile males intermediate between adult females and adult males suffer disproportionately high mortality. It was earlier suggested that sexual selection increases body size in Willow Warbler males, but the present results imply additional selection pressures for increasing sexual dimorphism.
URL:http://dx.doi.org/10.1111/j.1474-919X.1985.tb05078.x
Short Title:Ibis
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