DIET OF GALEMYS PYRENAICUS (GEOFFROY, 1811) IN THE NORTH OF THE IBERIAN PENINSULA

摘要

In this study data about the trophic ecology of Galemys pyrenaicus in the north of the Iberian peninsula are reported, based on analysis of the digestive tracts of 46 specimens from the Quinto Real mountain range (Navarra). Diet composition, trophic niche width and seasonal variations are described. The total number of prey identified was 2,629. The diet almost completely consisted of aquatic prey. The greater number of prey corresponded to Ephemeroptera larvae (46.6%), Trichoptera larvae (23.1%), Diptera larvae (13.3%) and Plecoptera larvae (9.0%). Trichoptera larvae provided 56.8% of the biomass, Diptera larvae 17.9% and Ephemeroptera larvae 16.1%. Galemys pyrenaicus does not select its prey by size, however a positive selection towards Ephemeroptera and Trichoptera larvae and a negative one towards Amphipoda was found. The results obtained mean that Galemys pyrenaicus can be characterised as a stenophagous species in which energy input is obtained from not-very-mobile invertebrates with a large amount of biomass (Trichoptera larvae), and other small but numerous and accessible taxons (Ephemeroptera larvae).