Abstract

The Northern Shrike Lanius borealis is a potential vagrant to northern and western Europe, both from North America (nominate borealis) and from Siberia (L. b. sibiricus). Currently, there are a handful of accepted European records, including three supported by DNA. There have been several other European claims of Northern Shrikes, especially from Finland, in recent years. A detailed study by the Finnish Rarities Committee, based on examination of museum specimens, led to the development of a multi-character scoring system. This highlights clear differences between many Northern and Great Grey Shrikes L. excubitor. Because some vagrants have shown intermediate characters, and mitochondrial DNA contradicted a seemingly obvious morphological Northern Shrike in Sweden, the Finnish Rarities Committee has opted not to accept records of Northern Shrike without DNA evidence. Nonetheless, the scoring system described here is a step forward in our understanding of the identification of Northern Shrike in a vagrant context1.1 A shorter version of this paper has been published in Finnish (in Linnut 3/2018) and in Swedish (in Roadrunner 4/2018), but more data and greater detail are presented here. IntroductionThere have been several claims of Northern Shrike Lanius borealis from northern Europe in recent years. Most of these come from Finland, with others in Sweden, the Netherlands and Lithuania, but also one from the Azores. In addition, there are two historical specimen records from Norway, one from the Netherlands and at least seven from Ukraine. Following the unexpected result that mitochondrial DNA (mtDNA) from an apparent Northern Shrike on Цland, Sweden, in October 2017, came from a Great Grey Shrike L. excubitor, the Finnish Rarities Committee has recently reviewed all Finnish records of Northern Shrike. That review concluded that claims from Finland could no longer be accepted without DNA evidence. Consequently, just one Finnish record (with DNA support) is currently accepted; all other claims were found ‘not proven’, including one previously accepted record.