The Morphometric Examination of Head Area of Black Headed Gulls (Larus Ridibundus) from Marmara Region

Abstract

The Black-headed gull (Larus ridibundus), a gull species commonly seen on shores of Küçükçekmece lake located in Turkey’s Marmara Region. This bird does not show sexual dimorphism because as it has monomorphic feather characteristics like other gull species.. In order toperform sex discrimination in gulls, the effective discriminant function analysis (DFA) method is used for the measurements based on theexternal morphology and determining the variables discriminating the two sex groups. The head morphological measurements and the bodyweights of 28 (14 males and 14 females) adult Black-headed gulls were obtained. One discriminant function was determined based on theresults. The accuracy rate in two sexes was determined to be 82.1% (85.7% female, 78.6% male) using the formula we obtained as a result ofthe discriminant function analysis in which the head length, determined to be more significant compared to the other variables, was used.The aim of the study is to assess the sexual dimorphism in population of Black-headed gull and represent a reliable method to make a sexdiscrimination along with discriminant analysis.