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Question Can a groundhog's shadow really predict if there will be six more weeks of winter?


No, the shadow-observing lore has no scientific basis and will not tell you if there will be six more weeks of winter. However, seeing wild groundhogs out and about during winter months might indicate that the season is almost over.

Woodchuck – Arctomys monax. L. Prang & Co. 1874. Library of Congress Prints & Photographs Division.

Groundhog Day

As the tradition goes, every year on February 2nd Punxsutawney Phil, the groundhog, comes out of his hole in Punxsutawney, Pennsylvania. If he sees his shadow, we will have six more weeks of winter. If he doesn’t see his shadow, we will have an early spring.

The tradition was brought to the United States from Germany, where it was not a groundhog but a badger who emerged from his den on February 2nd to predict whether spring would be arriving soon. When this tradition came to the United States in the late 1880s, a groundhog took center stage, as badgers were not native to the eastern U.S.

Phil is not the only hardworking groundhog, he’s just the most famous. There are five other states that have their own weather-predicting groundhog. If he does or does not see his shadow on February 2nd, it really has more to do with the weather that day than the groundhog itself. After all, Punxsutawney Phil has only been right about 40% of the time!

Groundhog in the Park. Shenandoah National Park, National Park Service Multimedia Gallery.

A Long Winter’s Nap

Groundhogs emerge from their winter hibernation in early to mid-February in mild climate areas. Male groundhogs emerge first to search their territory for burrows of females, where they may spend the night. These visits are so the animals get to know one another. When breeding season starts in March, the males will finally end their hibernation and leave their burrows and winter behind. About four weeks after mating, the females will give birth, and six weeks after that the new groundhog family will leave their burrow for good.

Hibernation enhances survival by saving energy during times of limited food. The ability to hibernate is found in several animal groups, including all marmots, many species of ground squirrels, chipmunks, hamsters, badgers, lemurs, bats and even some marsupials. Nestled in their burrows, they pass away the winter months. A groundhog’s hibernating heartbeat is only five beats per minute in comparison to 80 heart beats per minute in warmer months. Their breathing also slows down in the winter too. It can go from 16 breaths per minute to about two during their hibernation.

When they first come out of their burrows, groundhogs can tell if the winter is going to be harsh. An extended winter could delay the growth of the plants they need to eat after their long hibernation. They will delay their mating season and emerge later to make sure that there is food available. Since they lose over half their body weight during hibernation, this is very important for their survival.

This adult and juvenile groundhog pair were photographed on the campus of Brookhaven National Laboratory.  June, 2012.  U.S. Department of Energy, Brookhaven National Laboratory Flickr photostream.

What’s in a Name?

The names groundhog and whistlepig, are actually nicknames for the animal’s proper name of woodchuck (Marmota monax), which is in the Marmot family. Unlike the children’s rhyme of “how much wood could a woodchuck chuck,” the name has nothing to do with wood. Rather the name comes from the Native American word “wuchak.” The nickname whistlepig comes from the animal’s high pitch whistle-like warning cry. Depending where you live in the United States, there are different names for the woodchuck.

Marmots live together in a large burrow with their extended family and are very sociable creatures. Although woodchucks are members of the same family, they are very different from their marmot cousins. Woodchucks are solitary creatures, and unless the female is taking care of her young, they live alone.

Yellow-bellied Marmot lying on boulder.  2010.  Grand Teton National Park, U.S. National Park Service NPGallery.

Interesting Facts About Groundhogs:

  • Although they spend most of their time on the ground, they can also climb trees.
  • Young groundhogs are called kits, pups or cubs.
  • Since they are solitary, there is no name for a group of groundhogs, but a group of their marmot cousins is called a madness.
  • Their burrows can be up to 30 feet long and contain many different levels.
  • They can move up to 3 tons of dirt when creating their burrows.

Published: 1/16/2020. Author: Science Reference Section, Library of Congress

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