Annual Activity Cycle:
mean dates
In Southern Alberta, adult male Richardson's ground squirrels emerge from hibernation in mid- to late February. Male ground squirrels terminate torpor several days before emergence above ground, spending those days underground in a state of euthermy. During this time they eat cached seeds, permitting testicular recrudescence and accumulation of fat stores for the upcoming mating season. (see Reproductive Physiology)
The majority of adult female Richardson's ground squirrels emerge from hibernation in early to mid March, about two weeks afrer the emergence of males. Females mate within a few days of emergence from hibernation. In contrast to males, female ground squirrels emerge above ground almost immediately after termination of the final torpor bout. data
In southern Alberta, females give birth in an underground chamber in late March to early April, and litters first appear above ground from late April to early May. Young and adults spend the summer accumulating body fat in preparation for hibernation.
Adult male ground squirrels enter hibernation (immerge) from late May to early June, and adult females immerge from late June to early July. Juvenile females enter hibernation next from early to mid-August. Juvenile male ground squirrels remain active until mid-September to October.
Dates of annual events may vary by several weeks between years, and are ususlly several weeks later in more northerly and more easterly locations than in southern Alberta.
Richardson’s ground squirrels are strictly diurnal, coming above ground only during daylight hours. data Their eyes, which are adapted to make the transition from the total darkness of the burrow to the bright light above ground, have a cone-dominant retina and a pigmented lens. Consequently ground squirrels have poor vision in the dim light of dawn and dusk.
