Seasonal Activity Cycle and Weight Changes of the Franklin's Ground Squirrel

Abstract

Annual activity patterns and weight changes of adult Franklin's ground squirrels (Spermophilus franklinii) in North Dakota were recorded during 1981 and 1982. Timing of emergence, immergence and weight gain differed between years and among males, parous females and nonparous females. Males emerged from hibernation in mid-April, ca. 2 weeks ahead of females. Parturition occurred during late May and early June and young appeared above ground in late June through early July. Males and nonparous females began entering hibernation in early August followed by parous females in midto late August. During all sample periods, mean weights of males were significantly greater than those of parous females (P<0.04). Accumulation of most fat reserves for hibernation was concentrated during the month preceding immergence.