Demography of Capercaillie Tetrao urogallus in North-East Scotland. I. Determining the Age of Scottish Capercaillie from Skull and Head Measurements

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Abstract
Kirikov''s (1944) method for determining the age of Capercaillie from skull ossification was re-examined using Scottish birds shot in October-January. For both sexes, young of the year, yearlings and adults were readily recognized. The claim that adults can be separated into further age-classes may be true for cocks but was not confirmed for Scottish hens. Freshly-shot cocks, but not hens, can be separated into young, yearlings and adults from measurements of beak depth and head width, without the need to prepare skulls.