Which type of hibernator enters hibernation annually regardless of food or temperature?

An obligate hibernator enters hibernation annually regardless of food availability or ambient temperature.

Obligate hibernation is primarily governed by seasonal or circannual timing cues. The animal prepares for winter dormancy even when conditions are relatively mild and food remains accessible. Many ground squirrels, European hedgehogs, other insectivores, monotremes, and marsupials are described as obligate hibernators.

During hibernation, these animals reduce body temperature, heart rate, breathing, and metabolism. Their torpor is usually interrupted by brief arousals in which body temperature returns toward normal. Researchers still debate the exact purposes of these periodic warm-ups; proposed explanations include sleep regulation, energy management, and immune-system activity.

The term is often confused with facultative hibernation. A facultative hibernator responds more directly to immediate stress, such as cold or food shortage. The white-tailed prairie dog is a classic obligate hibernator, while the closely related black-tailed prairie dog is facultative.