Feather keratins, morphology and ecology in the taxonomy of crossbills and redpolls

• Main Author: Knox, Alan G.
• Published: University of Aberdeen 1977
• Subjects: 598.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.462303

The Scottish Crossbill, described as Lexis' curvirostra scotica, is shown to be more closely related to L.c.curvirostra than to L.pytyopsittacus (with which it had often been placed) in voice and morphology. Field studies in north-east Scotland revealed scotica and curvirostra breeding side by side, with considerable apparent ecological overlap, thus preventing their treatment as conspecifics. It is concluded that the Scottish Crossbill must be recognised as a full species, L.scotica. L. pytyopsittacus is confirmed as a valid species. Crossbill hind limb assymetry correlated with the direction of bill crossing is described. In an examination of redpoll museum skins, no difficulty was found in assigning supposed hybrids between Acanthis f.flammea and A, homemanni exilipes to one race or the other, and there appears to be no proof of hybridisation in the literature. It is concluded that hybridisation must be rare (or the hybrids are at a selective disadvantage) if it occurs at all. Similarly, the Icelandic birds, which are supposed to be a hybrid swarm, were found to fall into two plumage types with the same measurements, one like A.f'.roatrata (common) and the other like A.h.homemanni (rare). However, the bill length is significantly smaller than that of either supposed parental type, A.f .rostrata and A. h.homemanni. The evidence examined confirms the classification of redpolls into two species, A.flammea and A.homemanni, but the need for field studies is recognised. Reduced and carboxymethylated barb keratin (SCMK) from a variety of species were studied by electrophoresis on polyacrylamide gradient gels. Species-specific patterns were found for all the well-defined species examined, and the results suggest relationships which agree well with published classifications. The technique shows immense potential as a source of taxonomic information. When applied to the crossbills and redpolls the results confirm the very close relationships within these groups, and suggest further evidence of affinities between-races.