Why do some rodents hibernate while others remain active all year?

Some rodents hibernate as an evolved adaptation to survive periods when food supplies become scarce, such as during the winter months. By entering a state of deep dormancy, these animals bypass the need for high energy expenditure when resources are unavailable.1

The decision to hibernate or remain active is often a trade-off between energy conservation and the need to escape environmental dangers. Some rodents, such as chipmunks, are considered "shallow hibernators." This state serves as a compromise, allowing them to save energy while remaining capable of escaping predators or environmental threats like burrow flooding.2

Factors influencing whether a rodent hibernates include:
* Food Availability: Hibernation allows animals to survive when food is scarce.1
* Climate: In regions with milder winters, some animals may hibernate for only brief periods or not at all.1
* Metabolic Strategy: True hibernators, such as marmots and ground squirrels, undergo complex physiological changes—including dramatic reductions in heart rate, respiration, and body temperature—to maintain a minimal metabolic level.345
* Energy Budget: For some species, the metabolic cost of entering and emerging from deep hibernation is too high to be efficient, leading them to adopt different survival strategies.2