In a taxonomic world of splits and lumps (and particularly splits), the classification of the Scottish Crossbill still invites a good degree of scepticism. It was long recognised that many of the crossbills of the Caledonian pine forests of Scotland looked a bit different from other crossbills, particularly in the bill shape. The bill is ‘half way’ between a Crossbill’s and Parrot Crossbill’s in depth. In 1980, the BOU officially split the species, recognising Scottish Crossbill as a separate species, and the only full species of bird endemic to the UK.
More recent studies have suggested that the calls of Scottish Crossbills are also slightly different from other crossbills. So, for now, the species stands. Of course the name crossbill
comes from the birds’ unique crossed mandible tips, which help them extract seeds from conifer cones.