Using wing length for sexing Eurasian Skylark Alauda arvensis: examples from a British population

ABSTRACT The Skylark Alauda arvensis is a common, yet rarely ringed species. Outside the breeding season, determining the sex of individual birds is problematic. While previous studies have provided sexually dimorphic ranges of wing length, those based on accurate DNA sexing focus on Continental populations, which are subject to seasonal influxes of migrants. In Britain, Skylark is largely a sedentary species, and Continental guidelines on in-the-hand sexing might be inappropriate. Here we present a comparative analysis of morphometrics and DNA sexing for 137 individual Skylarks, to assess the accuracy of using wing length to sex trapped birds. We suggest that birds with wing measurements of 107–109 mm be classified as of ‘undetermined’ sex, with those below this range being classified as female and those above as male.