Proporción de sexos en una población de Arvicola terrestris (Rodentia, Arvicolidae) del NE de la Península Ibérica

Abstract

Sex ratio in a population of Arvicola terrestris (Rodentia, Arvicolidae) from the northeastern Iberian Peninsula
In this study the sex ratio in an Iberian population of Arvicola terrestris is examined. Data on the sex ratio in different age classes and in different seasons are given. The analyzed specimens (n = 684) come from monthly captures that took place between July 1983 and December 1984 in the area situated between the localities of Arros and Aubert, in the Arán Valley (Lérida, Spain). The total sex ratio is significantly different from the expected 1:1 relation, tipping toward females. Monthly analysis of the percentage of sexes shows an oscillation throughout the year, with a predominance of females during most of the year. The causes for this sexual unbalance, mainly in the adult component of the population, are discussed.