Happy Groundhog Day! Today is the day each year in which we look towards a giant rodent to find out how much more winter we'll have to endure. This year, we probably know the answer: winter hasn't been very wintery, even for Los Angeles. Which, well, isn't ever really wintery at all.

According to tradition, the groundhog (Marmota monax) peeks out of its burrow today, and checks to see if it has a shadow. If sunny enough for a shadow, the groundhog will return to the comfort of its burrow, and winter will continue for an additional six weeks.

In honor of the holiday, I've rounded up seven things about groundhogs that you probably didn't know. One for each extra week of winter we're going to have, plus one extra for good luck.

1. A groundhog by any other name. Groundhogs are also variously referred to as woodchucks, whistle-pigs, or land-beavers. The name whistle-pig comes from the fact that, when alarmed, a groundhog will emit a high-pitched whistle as a warning to the rest of his or her colony. The name woodchuck has nothing to do with wood. Or chucking. It is derived from the Algonquian name for the critters, wuchak.

2. Home sweet home. Both male and female groundhogs tend to occupy the same territories year after year. For females, there is very little overlap between home ranges except for the late spring and early summer, as females try to expand their territories. During this time, their ranges may overlap by as much as ten percent. Males have non-overlapping territories as well, though any male territory coincides with one to three mature females' territories.

3. Baby groundhogs! Infants stick around home for only about two to three months after being born in mid-April, and then they disperse and leave mom's burrow. However, a significant proportion - thirty five percent - of females stick around longer, leaving home just after their first birthdays, right before mom's new litter arrives.

4. Family values. In general, groundhog social groups consist of one adult male and two adult females, each with an offspring from the previous breeding season (usually female), and the current litter of infants. Interactions within a female's group are generally friendly. But interactions between female groups - even when those groups are shared by the same adult male - are rare and aggressive. Even though daddy woodchuck doesn't live at home, from the breeding season through the first month of the infants' lives, he visits each of his female groups every day.

5. Medical models. Groundhogs happen to be a good animal model for the study of hepatitis B-induced liver cancer. In fact, if infected with Woodchuck Hepatitis B virus, the animal will always go on to develop liver cancer, making them useful for the study both of liver cancer and of hepatitis B.

6. Look up! Though they spend most of their time on or under the ground, groundhogs can also climb trees.

7. Eskimo kisses. Groundhogs greet each other with an odd variation of the eskimo kiss: one groundhog approaches and touches his or her nose to the mouth of the second groundhog. Or, as scientists call it, they make "naso-oral contact."

Meier, P. (1992). Social organization of woodchucks (Marmota monax) Behavioral Ecology and Sociobiology, 31 (6) DOI: 10.1007/BF00170606

Photo: Wikimedia Commons/April King.