Every Feb. 2, Americans turn to a groundhog to see whether winter will stick around. But Groundhog Day is about much more than shadows and more weeks of cold. The tradition began in 1886, when the first Punxsutawney Phil was crowned in Pennsylvania.

Groundhogs emerge from their burrows around Feb.4. This fits the folklore of Groundhog Day, but predicting the weather is not their objective.

Hibernation is a remarkable adaptation that mammals living in colder regions have developed to survive the winter months when food is scarce. Animals slow down their heart rates, lower their body temperature,