Interspecific Interactions Between the Shrews Sorex Araneaus L. and S. Minutus L. (Soricidae, Insectivora) and the Use of Habitat: a Laboratory Study*)

Indirect evidence of various kinds demonstrated that the shrew species Sorex araneus and S. minutus show a partial vertical difference in habitat. This study aimed at verification of this habitat difference through direct observation of the animals in an imitation of the habitat under standardized laboratory conditions. Secondly, possible mechanisms responsible for the difference in habitat use were investigated. Proof was found for vertical habitat difference: S. minutus is more active in the upper layers, whereas S. araneus remains largely underground. The evidence indicates the establishment of habitat difference in young animals very soon after weaning early in summer and confirms earlier data as to its disappearance in spring, coinciding with sexual maturation. Furthermore, the effects of interaction between the two species in the laboratory are not likely to play an important role in selection of habitat in the field.

Affiliations: 1: Zoological Laboratory, Department of Population Biology, University of Leiden, Kaiserstraat 63, Leiden, The Netherlands