In the world of Kentucky wildlife, there are light sleepers and there are deep sleepers. Raccoons and skunks are light sleepers; they enter a state called torpor but will wake up and forage during warm spells in January.

The Groundhog (also known as the Woodchuck or Whistle Pig) is different. It is one of the few “true” hibernators in our region. When a groundhog goes down for the winter, it is out cold.

Understanding this cycle is critical for homeowners who want to protect their gardens and foundations. If you know when they wake up, you can be ready.

The Physiology of Hibernation

Groundhog hibernation is a medical marvel.

• Body Temperature: Drops from 99°F to as low as 37°F.
• Heart Rate: Slows from 80 beats per minute to just 4 or 5 beats per minute.
• Breathing: Slows to one breath every few minutes.

They survive entirely on the thick layer of fat they built up during the summer and fall. During this time, they are in a deep coma-like state in a winter burrow, which is often located in a wooded area or fenceline, distinct from their summer burrow under your deck.

The Timeline: When Do They Emerge?

October - November: The retreat begins. By the first hard frost, most groundhogs have sealed themselves into their winter dens below the frost line.

February: The “False” Awakening This is where the Groundhog Day legend comes from. In Kentucky, male groundhogs often wake up briefly in February. They emerge from their burrows, groggy and thin.

• The Mission: They are not looking for food (there isn’t any yet). They are looking for females.
• Scouting: The males travel to female burrows to introduce themselves and establish territory. They don’t mate yet; they just want to know where the potential mates are located.
• Return to Sleep: After a few days of scouting, they go back underground to sleep for another month.

March: The Real Season Begins As temperatures rise and the first green shoots of clover and dandelion appear, the groundhogs emerge for good.

• Mating: Breeding happens immediately in early March.
• Feeding: They are ravenous. They have lost up to half their body weight. This is when they are most destructive to early spring gardens.

April - May: The young are born. A litter typically has 2-6 pups. By late May, you will see the “chucklings” emerging to explore.

Why This Matters for Homeowners

1. The Window of Opportunity The best time to seal a burrow under a shed or deck is when you are 100% sure it is empty.

• Late Winter (Jan-Feb): If you haven’t seen activity since October, the burrow under your deck might be a “summer home” that is currently vacant. However, you must be careful. Sometimes they hibernate in the same spot.
• The Test: Fill the hole loosely with newspaper. If it stays in place for 3-4 days during a warm spell, the hole is likely empty.

2. Garden Prep If you wait until you see a groundhog to fix your fence, it’s too late. You need to inspect and reinforce your garden fences in late February.

• Check for gaps dug under the wire.
• Ensure the “floppy top” of your fence is secure.
• Clear brush around the perimeter.

3. Trapping Strategy Trapping is most effective in early spring (March/April) when food is scarce. They are easily lured by fresh cantaloupe or broccoli because there is little competition from natural vegetation. If you wait until summer when the world is green, they are harder to bait.

If you see a large dirt mound appearing next to your foundation in March, the season has begun. Call Critter Removal of Louisville to handle the problem before they start a family under your house.