You will notice on your next trip to Manning Park that as you set up your picnic at Lightning Lake, there are very few ground squirrels popping out of their burrows to see what’s for lunch.
But where did they go?
They have bulked up and gone down into their burrows to hibernate!
The Columbian Ground Squirrel spends only a few months above ground, emerging from its burrow in early spring to reproduce and indulge in all the delicious berries, seeds, roots, leaves, and grasses Manning Park has to offer before retreating to hibernate in mid-late-August. These squirrels live in fairly large colonies, and during spring and summer nights they retreat into elaborately constructed burrows to sleep, hide from predators, and give birth to their young.
Females actually enter hibernation later than males, because depending on when they have babies, the females have to first wean their litters before they can bulk up and gain the weight necessary to hibernate. So, females giving birth late in the season are among the last to enter hibernation.
When it’s time to hibernate, the ground squirrels construct a hibernaculum: a safe place to sleep throughout winter. A ground squirrel’s hibernaculum is built in burrows below the frost line, lined with a nest of finely shredded grass, and closed off with dirt at the entrance. During hibernation, a ground squirrel’s heart rate decreases and its temperature drops significantly as it waits for the colder months to pass by.
See you in the new year, Columbian Ground Squirrel!