BIOMETRIC DIFFERENCES BETWEEN AGE AND SEX CLASSES OF THE LEVANT SPARROW HAWK ACCIPITER BREVIPES ONMIGRATION AT EILAT, ISRAEL

Abstract

The Levant sparrow hawk (Accipiter brevipes) is a typical raptor with reversed sexual size dimorphism wherein the female is larger than the male. Here, we present the factors contributing to biometric differences between the age and sex classes. Starting from 1984, 1164 Levant sparrow hawks were captured and banded in the area immediately to the north of Elat, Israel. Comparing mean values, feather-dependent characters were 6.6–7.3% larger in adult females than in adult males, and 6.2–6.8% larger in second year females than in second year males. Differences were greater for culmen and hallux length and for body mass. We found wing cord and body mass to be the parameters most efficient in separating sex or age classes. Upon performing discriminant analyses on our data set, we found that hallux length varied independently between males and females, irrespective of the age of the bird. Our data establish that the Levant sparrow hawk is the least dimorphic of the European Accipiter species but has a sex-speci...