Post‐fledging wing and bill development in the RazorbillAlca torda islandica

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Abstract
Razorbills Alca torda, live, dead, and museum skins, were examined to establish the relationship between bill grooves and age. Patterns of growth and development to adulthood are shown for wing length and bill depth. Measurements of wing length, bill dimensions and total head length differed significantly between sexes in some samples, but not adequately to sex individual birds. Mean shrinkage of wings, after post‐mortem drying, was 2 mm (range up to 6 mm) in the first two months, nil or negligible thereafter. Bill depth, wing length and numbers of bill grooves in adults are probably linked with inherent size rather than with age of individuals.