STRUCTURE, LOCATION AND AVAILABILITY OF HIBERNACULA OF COLUMBIAN GROUND-SQUIRRELS (SPERMOPHILUS-COLUMBIANUS)

The hibernacula of 39 Columbian ground squirrels from populations at 2 elevations in SW Alberta were excavated and compared for differences in structure and location between age/sex classes within and between populations. Squirrels at high elevation (HE) used hibernacula that were larger and shallower than those at low elevation (LE). Size of hibernaculum was proportional to the weight of the occupant except that adult males used hibernacula larger in proportion to their weight than did adult females or juveniles. Adults at LE used deeper hibernacula than did juveniles; the same trend was seen at HE, but some juveniles also occupied large and deep hibernacula. Juveniles usually hibernated close to their mother and siblings, those that hibernated >20 m from relatives being less likely to survive winter. Juveniles use hibernacula within the natal burrow system when available and may not construct their own chambers. -from Author