Weathering the Cold, Part One: Brumation
By Taylor Buley
Illinois is home to over 54,000 different species of wildlife, and the majority are species of insects. Often, the time of year dictates when we can see some of our more familiar species. As fall and winter begin to make their way into Illinois, the animals we see moving around begin to change. But where do our animal friends go if we are not seeing them anymore? When winter moves into Illinois, animals who cannot handle the cold generally have three options: Brumate, Hibernate, or Migrate.
Brumation is the term used for the period of inactivity some ectothermic (cold-blooded) animals experience in the winter months. Because ectotherms cannot control their internal body temperature, as the outside world cools, so do they – and brumation is an adaptation that evolved to keep them alive in cold conditions. While brumating, many animals stop eating and will very occasionally wake up to drink. Snakes, lizards, and terrestrial turtles will burrow or find a hole in the ground or fallen tree to rest in. Aquatic turtles will bury themselves in mud at the bottom of their pond or stream to brumate. During this time, they will absorb oxygen directly from the water and through their skin, allowing them to stay underwater for several months. Some examples of Illinois reptiles that brumate are box turtles, painted turtles, blue racers, gray rat snakes, and many more of our approximately 65 reptilian species.
Reptiles are not the only ones who brumate. Frogs, toads, and salamander species in Illinois also brumate! Most frog species survive our winters by brumating in the mud in ponds, rivers, and lakes. The mud acts as insulation, keeping their body temperatures above freezing. American toads will bury themselves in soil below the frost line to survive winters. They will move up and down within the soil depending on how far the frost line penetrates. Some frogs, such as wood frogs and gray tree frogs, can brumate in leaf litter or under tree bark. These species accumulate glycerol in their body which moves through their system and acts as antifreeze, allowing them to survive the freezing temperatures. Salamanders, such as tiger salamanders and small-mouthed salamanders, will find shelter under logs and leaf litter and in burrows or rocky crevices to brumate.
