Continental great spotted Woodpeckers dendrocopos major in Britain – further analyses of wing‐length data

Abstract

Recent studies have suggested that the wing lengths of British Great Spotted Woodpeckers Dendrocopos major anglicus are more variable than originally thought and raised questions about the occurrence of continental races of Great Spotted Woodpeckers in Britain. In this study, wing‐length data from the British Trust for Ornithology database were used to explore in more detail the patterns of occurrence of long‐winged birds. Because of the larger sample size, the range (122–141 mm) is bigger than that quoted in standard texts and overlaps that for the nominate continental race D. m. major and also D. m. pinetorum. Only in extreme cases is it possible to determine the race of an individual bird on wing length alone, although patterns of occurrence of long‐winged birds are informative. There was an excess of long‐winged birds (>139 mm) trapped at all east‐coast sites, particularly in Scotland and in the irruption year of 2001/02. In non‐irruption years, there was an excess of long‐winged birds at east‐coast sites in Scotland but not elsewhere. The origin of these long‐winged birds is still unclear but is most likely to involve birds from Scandinavia. Measurements of other characters, such as bill length and depth, may throw more light on this and help decide whether distinct subspecies exist, rather than there being a cline from western Europe through Scandinavia to Siberia.