What do snakes do in the winter?

November 8, 2021

How do cold-blooded animals deal with cold weather? We had lots of questions about snakes in the winter and Dr. Allison had lots of answers! Keep reading to learn about what snakes in Illinois do in the winter when it gets cold.

“What do snakes do in the winter? Do they hibernate?”

Reptiles, including snakes, and amphibians brumate over the winter. It’s not hibernation, which warm-blooded animals do. Instead, snakes stop eating as the temperature drops, their metabolism slows down, and they look for an underground place to hide from surface temperature changes. Snakes are less active over the winter, but will still come to the surface to drink on warmer winter days, but they won’t eat until spring.

“Where do snakes spend the winter?”

Snakes overwinter underground in a hibernaculum. A hibernaculum is a place where several hundred to several thousand snakes spend the winter together brumating. Multiple species of snakes can be found in a single hibernaculum. Both juveniles and adult snakes will follow each other’s scent trails to a hibernaculum.


Garter snake photo by Dr. Allison


Smooth greensnake photo by Dr. Allison

“What types of places do snakes use as a hibernaculum?”

Snakes will overwinter in a variety of places. Some snakes will spend the winter in tunnel systems, like inactive ant mounds in a prairie, where they can get below the frost line. Oftentimes, smaller snakes and juvenile snakes spend the winter deeper underground than larger snakes. The most cold-hardy snakes that emerge first in the spring, like garter snakes, are found closer to the surface, as opposed to smooth greensnakes, which are less cold tolerant, and are found deeper underground. Other snakes, like the massasauga rattlesnake, will brumate in crayfish burrows below the water table.

If there aren’t any natural areas to get below ground, some snakes will use above ground structures, like large rotting logs in oak savannas, or human structures such as mulch piles, railroad embankments, or basements. Railroad tracks or rails to trails paths can act as snake highways that lead snakes into restored habitat areas.

“When do snakes leave their hibernaculum?”

Different types of snakes will leave their hibernacula at different times and temperatures. Garter snakes are one of the first snakes to emerge in the spring, northern water snakes are one of the later snakes to emerge. More snow in the winter is better for snakes. The snowpack buffers the hibernaculum from surface temperature changes, and helps prevent false starts of snakes emerging too soon due to early high temperatures.

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