Annual cycle of activity and weight changes in Richardson's ground squirrel, Spermophilus richardsonii

Data were gathered on annual activity cycle, lactation, growth, and weight changes in a population of Richardson's ground squirrels in southern Saskatchewan.Adult males emerged from hibernation in late March and females emerged in early April.Adult males entered hibernation in early July, followed by adult females in late July.Young emerged from the nest burrow in the last week of May and early June.By mid-August young constituted 100% of the active population.Young males entered hibernation later than young females.All age classes of adult females reproduced, with 92-100% lactation each year of the study.Yearling females emerged from hibernation significantly lighter than older females.Some data suggests that heavier animals in the adult male, young male, and young female classes are more likely to be found on the study area following hibernation than lighter ones.Adult and young males were consistently heavier than adult and young females respectively.