Ask an Expert: Slithering Snakes Spotted in Parks and Lawns

Terry Messmer


View as a pdf

garterJust in time for Halloween, an increased number of snakes have recently been reported in lawns, golf courses and city parks. Aside from callers being spooked by an unexpected encounter with a snake, they are also concerned about the snakes harming them, their children or taking up residence in their homes. 

Luckily, the snake at the center of this seasonal controversy is none other than the common garter snake. This non-venomous snake, sometimes called a garden snake or water snake, is the common name given to the nearly harmless, small-to-medium-sized snakes in the genus Thamnophis. Garter snakes are found throughout most of North America, and three species are found in Utah. Garter snakes generally inhabit areas where water is available year round. These areas provide the groceries – amphibians and insects – to feed the snakes.

So why do the snakes seem to be massing on lawns this time of the year? Like all reptiles and amphibians, gartersnakes are cold-blooded, or poikilothermic, and use the sun to regulate their body temperature. Thus, garter snakes that live in cold climates like Utah must hibernate to survive the winter. Before the snakes go into hibernation, they stop eating for about two weeks to clear their stomachs of any food. During hibernation, garter snakes typically occupy large, communal sites called hibernacula. These dens can include rock piles, outcroppings and even foundations of abandoned buildings – basically any open space below the frost line that provides overhead protection. The dens often contain hundreds of garter snakes. One den in Canada was the hibernation spot of more than 8,000 snakes. To get to the den sites, snakes will migrate long distances in large groups. This ritual occurs both in the spring and fall, and that’s why so many are being spotted this time of year.

Garter snakes have complex systems of pheromonal communication. They can find other snakes by following their pheromone-scented trails. As they leave the den in the spring, they release these pheromones to mark the trail.

If you see these snakes massed in your lawn, the best advice is to ignore them. They are timid and will try to avoid you at all costs. During these migrations, they are also very susceptible to predation, and many of them do not make it to the den sites. Hawks, crows, raccoons, crayfish and other snake species, such as the king snake, will eat garter snakes. Shrews and frogs will even eat the juveniles.

Because of their conservation benefits, garter snakes are a protected species in Utah.  However, at times they may try to take up residences in homes. If this happens, contact your local county Extension office. For more information about garter snakes in Utah, refer to this fact sheet.

By: Terry Messmer, Utah State University Extension wildlife specialist,, 435-797-3975