Insulation capacity of litter mounds built by Mus spicilegus: physical and thermal characteristics of building material and the role of mound size

Abstract

In contrast with house mice (Mus musculus musculus and Mus musculus domesticus), Mus spicilegus is seasonal in its reproduction. Thus overwinter survival seems to be an important factor for population dynamics. In autumn, the mice construct voluminous mounds made of plant material covered with soil, under which they overwinter without reproducing. These mounds could be used for food storage but a thermoregulatory function is a non-mutually exclusive explanation. In this study we investigated the influence of different plant material and mound size on insulation capacity and whether active heating owing to the fermentation process of the organic plant material does occur. We found no indication for active heating processes owing to fermentation but we did find that plant material seems to be important for temperature absorption capacity, although we found no indication for insulation capacity. Furthermore, mound size seems to have a significant effect on thermal stability.