Figure 2

The timing of entry into hibernation (mean ± SE) relative to the onset of 100% snow-cover (solid black line at ‘0’ on the x-axis) of free-living young-of-the-year (YoY) arctic ground squirrels from two populations living 20 km apart in northern Alaska. The time of birth is not shown (faded part of bars), however, it is important to note that although the time when YoY entered hibernation is significantly different between the sites and the sexes, the length of time they (females or males) remained active above ground was not (114–116 days for females; 130–134 days for males).