All Groundhogs have 22 teeth.

Groundhogs hibernate one to a burrow, with at least two doorways.

Each Spring males emerge earlier than females.

Groundhogs can lose at least 50% of their body weight during hibernation. The average weight of a groundhog is 10 kilograms = 22 lbs.

Groundhogs can swim and climb trees. They have a top speed of 15 kilometers per hour (9.3 miles per hour.)

Groundhog day was once celebrated by the ancient Celts. It is half way between winter solstice and spring solstice.