Sexual size dimorphism and determination of sex in Atlantic yellow-legged gulls Larus michahellis lusitanius from Northern Spain

Authors: Aitor GALARZA, Jon HIDALGO, Gorka OCIO and Pilar RODRÍGUEZ

E-mail: agalarza@telefonica.net

Published: Volume 55(1), June 2008. Pages 41-47.

Language: English

Keywords: Larus michahellis lusitanius, Iberian Peninsula, discriminant function analysis and sexual dimorphism

Summary:

Aims: We evaluate sexual size dimorphism in Atlantic yellow-legged gulls Larus michahellis lusitanius and provide a discriminant function to sex gulls in hand.

Location: Two islands of the Basque Country (Northern Spain).

Methods: Incubating gulls were trapped, banded, weighted and measured. A drop of blood was extracted for molecular sexing. After testing for sex differences in body size and weight, discriminant function analyses were performed to identify the best traits for sexing.

Results: Body measurements in males were significantly larger than in females. Within each pair, males had larger head length, bill depth, long bill length and body mass. Discriminant analysis indicated than the combination of three measurements (head length, bill depth and wing length) predicted correctly the sex of 98.5 % of individuals.

Conclusions: The discriminant function described by Bosch (1996) cannot be used to identify sex properly in Atlantic Iberian yellow-legged gulls because they are significantly smaller than their Mediterranean counterparts. No significant differences were found with yellow-legged gull populations from Western extreme of Cantabrian coast (Galicia). Therefore, we conclude that the developed discriminant function can be applied to other Atlantic yellow-legged gull populations from Northern Iberian Peninsula, thus, providing a highly accurate, inexpensive and fast method for sexing in hand this Iberian gull subspecies.

Full Article:

Full Article

Enter your email and password to access the contents of the subscribers of the magazine. If you are not subscribed click here





We use own and third party cookies for the proper operation of the Website, carrying out analytical metrics, showing multimedia content and advertising, and interacting with social networks. More information in our Cookies Policy.
Accept Exit