Ageing and sexing of the snow finch Montifringilla nivalis by the pattern of primary coverts

Abstract

We provide here new methods of sexing and ageing the snow finch Montifringilla nivalis, a bird localised on Palaearctic mountain ranges. Between 2003 and 2009 we caught, ringed, measured and took pictures of 108 individuals in order to study the development of plumage among different age and sex classes. In particular we focused on the pattern of primary coverts (PC), to test whether they provide a reliable character for sexing and ageing snow finches. In general males had smaller black markings than females, and older individuals smaller than younger. Juvenile females had completely black PCs, while males of the same age had a little white patch on the inner PCs. This provide a reliable character to sex even fledging or nestlings of snow finches. Males in second plumage were very similar to older females, but when they could be sexed with other methods, then the pattern of PCs could be used to reliably age almost all individuals up to third plumage, with only few intermediates that should be left undetermined.