Birds of Indian Subcontinent

Stable isotope evidence for different regional source areas of common crossbill Loxia curvirostra irruptions into Britain

Publication Type:Journal Article
Year of Publication:2008
Authors:Marquiss, M, Hobson, KA, Newton, I
Journal:Journal of Avian Biology
Date Published:2008
ISBN Number:1600-048X
Keywords:Fringillidae, Loxia, Loxia curvirostra, Norway, Pyrrhula, Pyrrhula pyrrhula, United Kingdom
Abstract:We used the stable isotope composition of body feathers to show the extraordinarily varying regional provenance of an irruptive conifer seed specialist, the common crossbill Loxia curvirostra. In the boreal region of the western Palearctic, this species specialises on the seeds of Norway spruce Picea abies. The patterns of deuterium in the feathers of migrant common crossbills collected in Britain suggested that irruptions in different years originated in widely separated regions of the Palearctic boreal forest. The birds from some irruptions were relatively narrow-billed compared with those from others, but bill width was not correlated with deuterium values. However, deuterium values did co-vary with the dates that the irruptions reached Britain, with the lowest deuterium levels in years with the latest arrivals. This finding was consistent with the idea that birds with low values came further, from regions far to the northeast. This pattern was very different from that found in irruptive northern bullfinches Pyrrhula p.pyrrhula which had larger variation in deuterium values within an irruption, suggestive of a much more widespread provenance. It is argued that the difference between species is the result of their differing foraging ecology. Bullfinches have a varied summer diet and, unlike common crossbills, do not concentrate regionally to breed where a single type of food is available that year.
Short Title:Journal of Avian Biology
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith