Invasion of Bullfinches Pyrrhula pyrrhula in western Europe in 2004: a mix of local, ‘trumpeting’ birds and others of unknown origin: Capsule In east Jutland, Denmark, the invasion included individuals of a small-sized local race P. p. coccinea, as we

Publication Type:Journal Article
Year of Publication:2006
Authors:Fox, AD
Journal:Bird Study
Volume:53
Date Published:2006
ISBN Number:0006-3657
Keywords:Denmark, Europe, Fringillidae, Pyrrhula, Pyrrhula pyrrhula, Western Europe
Abstract:Aim To determine the measurements, morphology, phenology of occurrence and abundance of the different forms of Bullfinch occurring during an invasion year in rural Denmark. Methods Seven years of ringing (including three years of colour-marking), recapture and resighting at a baited site provided information on voice, body size and mass dynamics of Bullfinches throughout the annual cycle. Results P. p. coccinea was most common during February and March, slightly less so in October and November, with fewer still at other times of year. Large P. p. pyrrhula were 30% heavier than coccinea and were rare winter visitors (mostly one to five individuals caught during November to March) in four years during 1998?2005. Exceptionally, 30 were captured during November 2004 to April 2005 and two autumn-caught birds wintered at the study site. Female: male sex ratio was higher amongst captured pyrrhula than coccinea. Proportions of first-winter birds amongst both races were not abnormally high. Most notable was the trumpet call (not reported from Denmark before) given by some large individuals in 2004/05, but never by coccinea, although some large birds gave normal calls, suggesting two origins for the large forms. Conclusion Unusually large numbers of three different forms of the Bullfinch in east Jutland from autumn 2004 suggested a general food shortage in their normal wintering areas. Rapid increases in body mass from about 30 g to over 40 g amongst the large Bullfinches immediately prior to their departure suggested an extended migration (potentially >1000 km) back to unknown breeding areas. By contrast, local coccinea birds showed modest declines in body mass at the same time. More research is needed to establish the origins of these birds and the precise cause of their exceptional appearance in that year.Aim To determine the measurements, morphology, phenology of occurrence and abundance of the different forms of Bullfinch occurring during an invasion year in rural Denmark. Methods Seven years of ringing (including three years of colour-marking), recapture and resighting at a baited site provided information on voice, body size and mass dynamics of Bullfinches throughout the annual cycle. Results P. p. coccinea was most common during February and March, slightly less so in October and November, with fewer still at other times of year. Large P. p. pyrrhula were 30% heavier than coccinea and were rare winter visitors (mostly one to five individuals caught during November to March) in four years during 1998?2005. Exceptionally, 30 were captured during November 2004 to April 2005 and two autumn-caught birds wintered at the study site. Female: male sex ratio was higher amongst captured pyrrhula than coccinea. Proportions of first-winter birds amongst both races were not abnormally high. Most notable was the trumpet call (not reported from Denmark before) given by some large individuals in 2004/05, but never by coccinea, although some large birds gave normal calls, suggesting two origins for the large forms. Conclusion Unusually large numbers of three different forms of the Bullfinch in east Jutland from autumn 2004 suggested a general food shortage in their normal wintering areas. Rapid increases in body mass from about 30 g to over 40 g amongst the large Bullfinches immediately prior to their departure suggested an extended migration (potentially >1000 km) back to unknown breeding areas. By contrast, local coccinea birds showed modest declines in body mass at the same time. More research is needed to establish the origins of these birds and the precise cause of their exceptional appearance in that year.
URL:http://www.tandfonline.com/doi/abs/10.1080/00063650609461445
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith