Biometrics, sexing and moulting of Snow Finch Montifringilla nivalis in Central Italy

Abstract

As a small passerine typical of several Palaearctic mountain ranges, the Snow Finch Montifringilla nivalis is susceptible to climate change and studies into its ecology are badly needed. Data on biometric measurements and moult parameters are essential to underpin ecological studies and the aim of this study was to provide such data for a central Italian breeding population. Between 2003 and 2009, 404 individuals were ringed and measured. In the majority of morphometric measurements (wing length, eighth primary length [P8], bill depth, bill length, mass) adults were significantly larger than juveniles. Adult males had longer wings than females, but the sexes were similar for all other size parameters. Differences in wing length could be used to sex safely 88% of all adult individuals. Wing and P8 length measurements were influenced by feather abrasion, which was more pronounced in females and reduced wing measurements by 2 mm in summer compared to winter. The duration of primary moult was estimated to be 85 days in juveniles, 80 days in adult males and 67 days in adult females. In general, adults started moulting earlier than juveniles and males earlier than females. As usual among passerines, secondary moult started later than primary moult in both juveniles and adults and was accomplished in 50 and 65 days, respectively.