Effects of hoard manipulations on life history and reproductive success of female red squirrels (Tamiasciurus hudsonicus)

Abstract

We conducted a series of hoard manipulations on the red squirrel (Tamiasciurus hudsonicus), a solitary species that constructs central food caches, to determine if the size and content of the hoard influenced the life-history parameters and reproductive success of females. Larderhoards of jack pine (Pinus banksiana) cones were experimentally increased in autumn of 1989 and 1990, and decreased in autumn 1989. In both years we also supplied sunflower seeds (a food item with high energy content and low handling time) to individual females. Our experiments had no significant effect on the survival of females (prior to parturition or after weaning), prepartum or postpartum body mass, size of litters, number of offspring emerging from nests, or number of offspring weaned. Parturition date was significantly earlier (P = 0.003) in females that received additions of seeds in the 1st year of the experiment. We also determined that control females harvested only a small fraction of the jack pine cones available on their territories. Our observations suggest that availability of food was not placing constraints on females during the years of our experiment. We also discuss possible reasons why dates of parturition (and estrus) were relatively more responsive to levels of food than our other measurements.