A typical human can go for less than a day without getting thirsty, but can only last for an average of three days without water. How do hibernating animals survive without water for such a prolonged period? It’s different for every animal.

First, take the thirteen-lined ground squirrel (Ictidomys tridecemlineatus). A research study by Jenkins et. Al. found that the squirrel goes for months without drinking water because of changes in the sensitivity of its thirst cues. The article states that the suppression of thirst comes from “physiological indicators of fluid deficit,” due to “activity of neurons in the circumventricular organs.” During hibernation, these cues become less activated, causing a lesser need for thirst.

The squirrels go through two physiological states during their hibernation: torpor and interbout arousal. The study explains that torpor in a squirrel is characterized by “suppressed metabolism and a body temperature of 2°C to 4°C,” lasting for two to three weeks.” Then, the squirrel enters the interbout arousal state, in which the animal moves around in its burrow, increasing its body temperature back to 37°C. Then, the cycle repeats for the extent of the hibernation.

American alligators may seem very different from squirrels, but they also have a similar hibernation strategy. American alligators are the northernmost living member of the Crocodilia species, living as north as North Carolina. In these states, winter freezes the water, and alligators must go through their own variation of hibernation, called brumation, to stay alive.

During brumation, alligators will poke their noses out of the water before it freezes over, and that gives them a way to breathe during the winter months. The South Carolina Aquarium states that the alligators “enter a low metabolic state where they engage in minimal activity, but still wake up and will drink.” They will also suppress their heartbeats from a range of 30-40 beats per minute to just 2-3 beats per minute, limiting the amount of oxygen they use.

Animals have astounding ways to survive through hibernation without growing thirsty. From limiting their neuron activity to poking noses out of the water, they all have something to help them hibernate successfully.