A Big Chill

Cooling Down with the Season

Animals in the wild hibernate in response to winter’s lack of food, shorter days and colder temps. Bears, most famously, hunker down in dens, slow their metabolisms, and wait for the warm weather to start producing their meals in the spring.

Because there is no shortage of food here at Lincoln Park Zoo and all animals are given the option to come inside to warm spaces, some species that hibernate in the wild skip the slumber. Our black bears at the Pritzker Family Children's Zoo, for example, gobble berries throughout the winter, sometimes romping in thecrisp outdoor air, sometimes relaxing on warm piles of hay indoors.

But hibernation does happen at the zoo. An off-exhibit area within the Children’s Zoo that houses smooth green snakes is cooled to 50 F, mimicking winter’s chill. The snakes become lethargic during this period, their metabolisms slow, then they bounce back to life when temps are raised in the spring.

This brumation, as it's known with reptiles, is crucial to maintaining their life cycles. They need to experience the changing seasons in order to fully develop and reproduce. A big chill in winter leads to big things the rest of the year.