Yellow-bellied marmots act like Eastern groundhogs

-A A +A
By Sylvia Brockner

Feb. 2 is Groundhog Day, a day that doesn’t have much significance here, but it does in the Northeastern states, especially Pennsylvania, where it started.

The myth is that if the groundhog comes out of his winter hibernation on Feb. 2 and sees his shadow, he is frightened and goes back to sleep for six more weeks. But if it is a cloudy day and he does not see his shadow, he will stay awake and spring will come early.

In the cold Northeast, six more weeks of winter or early spring is important, for everyone is sick of winter and eager to see robins running on their lawns. However, the eastern groundhog, or woodchuck, is not found in Colorado, and once awake these animals seldom go back to sleep again.

So, what are the creatures that look like woodchucks and whistle at us from every rock outcropping when we hike in the mountains in summer? They are yellow-bellied marmots. One of the easiest places to see these animals is along Mount Evans Road. They are closely related to the groundhog, as are ground squirrels and prairie dogs. The yellow-bellied marmot and the groundhog both have short legs and barrel-shaped bodies. The eastern woodchuck is all brown with dark brown or black feet. The yellow-bellied marmot is brown with a yellowish wash and a yellow belly. Its feet are usually buff to dark brown, and it usually has a buff or whitish spot on its nose between its eyes.

These marmots are first cousins of the woodchuck. They are a bit smaller, have a bit longer tail and are one of our largest rodents. They eat prodigious amounts of food. They are awake and remain awake as long as there are green, growing plants to eat. When frost puts an end to the growing season, they go into their burrows and hibernate until spring.

When they come out, they are very lean and hungry. This means they must have green, growing food to eat. Therefore, they eat tremendous amounts in late summer to store enough body fat to see them through the winter, which in the high mountains is often five months or more. They are true hibernators in that when they go into a deep sleep, they slow down all bodily functions and survive on their body fat.

At lower altitudes, they often emerge in February, thus the legend of Groundhog Day, but once they emerge, they seldom go back to sleep, even if they do see their shadows. They make do with what early greens they can find between snowdrifts, often leaving their wallowing tracks in the snow.

Another colloquial name for these animals is “whistle pig.” They have a clear, loud whistle, which they use as an alarm note, warning their young and all marmots within hearing that a predator has been sighted. At the sound of the whistle, the young and other marmots dive into the nearest burrow. They usually escape but not always.

In fact, I was sitting on a rock on Mount Evans just above timberline, sketching five young marmots that were playing outside their burrow, when the female suddenly whistled. They all dived for the same hole. Unfortunately, only four of them made it into the burrow. The fifth and last was grabbed by a marten and carried away.

The female had at the last minute dived into another escape hole, and the entire meadow was aware of what had happened, with sharp whistles rising from one marmot after another. The female had lost one of her young, and it took some time before the meadow quieted down and marmots began to poke their heads out of burrows again.

Marmots form an elaborate system of tunnels, which are usually but not always connected, so they have escape routes all over their territory. The main burrow leads to their nesting den, which is often as much as 2 feet wide and in which the female builds a nest of dry plant material lined with the finest and softest grasses available.

They also have side chambers along the tunnels that are used as toilets, and since they hibernate, they do not store any food. When they emerge in the spring, they may travel for some distance in search of a mate. The young are born about a month later and come out of the burrow to play in about another month when they are half grown.