ABSTRACT
Stored food is the primary source of energy during hibernation for small sciurid hibernators such as chipmunks (Tamias and Eutamias), whereas stored body fat is the predominant energy source for large sciurids such as marmots (Marmota). Although ground squirrels (Spermophilus), medium-sized sciurids that store fat preparatory to hibernation, have long been known to collect and cache seeds, the relationship between cached food and hibernation is unclear because little is known about the identity of cache owners or when caches are created or used. A significant sexual difference in duration of pre-emergence euthermy has been confirmed for S. columbianus and S. richardsonii from radiotelemetric studies of squirrels in natural hibernacula. W. T. Shaw, however, reported a sexual bias in the contents of the hibernacula of S. columbianus, noting that most males (12/17) but few females (1/9) had stored food.
