Habitat and food preferences in a guild of insectivorous mammals in the Western Pyrenees Enrique CASTIEN and Joaquim GOSALBEZ Castien E. and Gosälbez J. 1999. Habitat and food preferences in a guild of insectivorous mammals in the Western Pyrenees. Acta Theriologica 44: 1-13.The use of trophic and spatial resources in a guild composed of five species of insectivorous mammals (Galemys pyrenaicus, Talpa europaea, Neomys fodiens, Sorex coronatus, and Sorex minutus) was studied. The characteristics of the macrohabitat were studied based on data from trap lines. Those pertaining to the microhabitat were examined through a study of the sites where each animal was caught. The diet was studied by analysis of the digestive tract as well as the availability of resources in various microhabitats. The results show a high level of segregation in the use of trophic resources. The microhabitat used on the ground surface has a low level of segregation among the shrews. A comparison of the diet of each species with the results from the invertebrate sampling carried out in different microhabitats (water, subsoil, humus, ground surface) shows that there is a relation between the food consumed and its availability in the microhabitats utilised by each species. This study suggests that the coexistence among the insectivorous species studied may be explained by the use of the microhabitat and diet segregation. The differences in diet would be a consequence of the use of different microhabitats.

This paper describes the attempts to protect and re-establish threatened populations of the native freshwater crayfish, Austropotamobius pallipes, of Navarra, Spain. Three species of crayfish are presently thriving in Navarra, the native species A. pallipes and the introduced North American species Pacifastacus leniusculus and Procambarus ciarkii. Both species are known to carry the fungus Aphanomyces astaci in their cuticles and to transmite it to the native species. The management strategies implemented by the authorities in order to restore native populations of crayfish are discussed.

In order to provide a basis for the sustainable exploitation of the heavily hunted Iberian hare Lepus granatensis, we compared its reproductive parameters at the northern edge of its range, where it occurs at low densities, with those reported in other studies elsewhere within the species' range. Monthly samples totalling 212 Iberian hares (104 males and 108 females) were collected in the province of Navarra during November 2001 ‐ December 2002. Reproductive parameters varied only slightly from season to season. Sexually competent males, defined by the presence of epididymal spermatozoa, were present in all bimonthly periods. Reproductively active adult females were also present in all the bimonthly periods, although a slight seasonality was detected: the highest incidence of pregnancy and lactation (100%) occurred in March‐April, while the lowest incidence of adult females that were neither pregnant nor lactating (15%) occurred in September‐December. Mean annual litter size was 2.09 and the theoretical value of annual young production per female was estimated to be 16.1, which is much higher than estimates reported in studies of L. granatensis in Portugal and southern Spain. In Navarra, which is at the northern limit of the species' range, densities are low due to intense hunting. However, the observed reproductive potential was surprisingly high and facilitates recruitment to the population which could, to a certain extent, make up for the high hunting pressure in the area.

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DNA sequence comparisons suggest that evolutionary rates at the rabbit IGKC1 locus can differ among allelic lineages. Here we address the question of whether population turnover rates can vary among IGKC1 alleles. We studied the distribution of sixteen IGKC1 (or b-locus) allotypes in areas comprising the aboriginal species range (Iberian peninsula). Rabbits in this area belong to one of two distantly related mitochondrial lineages (mtDNA types) A and B. In the more recent distribution area of the species, all rabbits belong to the mtDNA type B lineage, and IGKC1 alleles b4 and b5 comprise over 90% of the gene pool. These two alleles are also predominant in areas of mtDNA type B prevalence within the Iberian range. However, in areas of mtDNA type A prevalence, the b4 and b5 allotypes are rare or absent; they apparently have been replaced by serologically related, but distinct, 'endemic' variants. The cytonuclear disequilibria were highly significant, also within the subsample consisting of populations from Spain. These observations suggest that allelic persistence times for the predominant IGKC1 lineages could be shorter than the divergence time of the major mtDNA lineages A and B. In contrast, the relative gene frequencies of the IGKC1 allele b9 were similar among the type A and type B rabbits; it was present in most populations at low frequency. In consequence, persistence times of the b9 allele appear to be longer than the divergence time of lineages A and B. The data reported here are in agreement with the DNA sequence data, providing further proof that the molecular clock can run at different rates among allelic lineages at the rabbit IGKC1 locus.