Environmental factors have little influence on the reproductive activity of the Iberian hare (Lepus granatensis)

Abstract

The two European hare species with the largest ranges, the brown hare (Lepus europaeus) and the mountain hare (L. timidus), have a marked seasonal pattern of reproduction, probably reflecting strong environmental influences during the year. In this work, we evaluate the role of some environmental factors on the reproductive activity of another European hare species, the Iberian hare (L. granatensis). The study was carried out in Pancas, southern Portugal, from mid-1997 through December 1999. Climatic data (mean monthly values of minimum and maximum air temperature, daylength and total monthly rainfall) were recorded at the nearest meteorological station. To assess abundance and quality of food, samples of the herbaceous vegetation were collected every two months and analysed for water, fibre and crude protein content. Iberian hares were collected every two months and live or post mortem analyses were performed. The proportion of males with external testes and of pregnant females as well as the weight of the gonads were recorded. While environmental variables had marked seasonal variations, the Iberian hare nevertheless showed continuous reproductive activity. In all sampled periods, males with external testes and pregnant females were observed. However, a slight decrease of sexual activity appears to occur, mainly in males, during autumn. Only the variation of male reproductive characteristics was significantly explained by multiple regression equations. Maximum regression coefficients were obtained with the climatic variables (minimum, maximum temperatures and daylength) and vegetation biomass of the preceding two months. Our data indicate that environmental factors have little effect on reproduction in the Iberian hare. The results are compared with those obtained for other phylogenetically and geographically close hare species, and with another leporid, the wild rabbit (Oryctolagus cuniculus algirus), which occurs sympatrically with L. granatensis.