Ge Determination in the Alpine Accentor Prunella collaris by Discriminant Analysis of Morphological Measurements

Abstract

1) Linear discriminant analysis was performed on external morphological measurements to distinguish yearling from older (≥2-year-old) Alpine Accentors Prunella collaris. 2) From 17 May to 15 June in 1985-1989, morphological variations in eight characters were measured in 148 known-age individuals inhabiting the top of Mt. Norikura, central Honshu, Japan. 3) In both sexes, older birds were significantly heavier and had longer wings and tails than did yearlings, but tarsus length, three bill dimensions and head length showed no increase with age. 4) Stepwise discriminant analysis was performed on body weight (BW), wing length (WL), and tail length (TL). The resultant final functions were as follows: Male: Z=0.592WL+1.008TL-131.330 Female: Z=0.411BW+0.504WL+0.353TL-87.300 Age classes were assigned based on the discriminant scores (Z), as yearlings when Z 0. 5) This analysis proved to be a useful aging method in its reliability and objectivity. By the discriminant function, males and females could be aged in 96.4% (80/83) and 86.2% (56/65), respectively. The classification success rate was much higher than that calculated by the discriminant analysis using a single variable.