| BIOMETRIC DIFFERENCES BETWEEN AGE AND SEX CLASSES OF THE LEVANT SPARROW HAWK ACCIPITER BREVIPES ONMIGRATION AT EILAT, ISRAEL |
REUVEN YOSEF A1, REUVEN YOSEF A2, LORENZO FORNASARI A3
A1 International Birding & Research Centre in Eilat, P.O. Box 774, Elat 88000, Israel
A2 Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
A3 Department of Environmental Sciences, II University of Milan Bicocca, Via Emanueli 15, I-20126 Milan, Italy
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 6.67.3% larger in adult females than in adult males, and 6.26.8% 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-specific hallux size.
The references of this article are secured to subscribers.