10/06/2026
THE SNAKE CROSSING YOUR YARD THIS OCTOBER MAY BE HEADING TO THE SAME WINTER DEN ITS KIND HAS USED FOR YEARS.
For most of the year, garter snakes are easy to think of as solitary animals.
One under a log.
One beside a pond.
One slipping through the grass.
But autumn changes the pattern.
As temperatures drop, many garter snakes begin moving toward places where they can survive the winter underground.
And sometimes they do not go alone.
The National Park Service notes that garter snakes can spend winter in communal dens containing hundreds of snakes. Some species begin moving toward these hibernation sites in October, sometimes traveling considerable distances to reach them. National Park Service
For a cold-blooded animal, finding the right place matters enormously.
A shallow hiding place may freeze too deeply.
A suitable winter den — called a hibernaculum — provides access to protected cracks, burrows, rock piles or underground cavities where temperatures remain survivable even when the surface freezes.
Common garter snakes typically enter this winter dormancy, more accurately called brumation, from late October into early spring across colder parts of their range. During that period, snakes that normally spend much of the year alone may gather together in surprisingly large numbers. National Park Service
And garter snakes are not always the only ones there.
National Park Service accounts describe winter dens shared by several snake species. Racers may overwinter alongside garter snakes, milk snakes, bullsnakes and even rattlesnakes. Bullsnakes have also been documented using large communal winter dens with multiple species. National Park Service
That makes a hibernaculum something far more important than a random hole in the ground.
It can be a piece of wildlife infrastructure used repeatedly across years.
Research on Great Basin rattlesnakes shows just how strong that attachment can become: individuals at communal dens show high fidelity to their ancestral hibernation sites, with nearly all returning in fall. Garter snakes are different animals, but the example reveals how critical a reliable winter den can become for snake populations in cold climates. National Park Service
For plains garter snakes at Jewel Cave National Monument, the seasonal timing is especially clear: beginning in October, the snakes start moving toward winter dens. National Park Service
So a snake moving across an exposed yard, trail or road this month may not simply be wandering.
It may be following one of the most important journeys of its year.
The destination could be an old rodent burrow.
A deep rock pile.
A crack beneath the frost line.
A limestone cavity.
Or a communal den already holding dozens of other snakes.
Once there, everything slows.
Reptiles do not hibernate exactly like mammals. During brumation, their metabolism falls dramatically and activity becomes minimal, although they may become briefly active during warmer periods.
Then they wait.
Weeks become months.
Snow covers the entrance.
The landscape above them freezes.
And somewhere underneath it, animals we usually imagine living completely separate lives may be spending winter almost on top of one another.
So the garter snake you see crossing the grass this October may be doing something much bigger than changing hiding places.
It may be going home for winter.
And when it disappears underground, hundreds of others may already be waiting there.
