What's Up, Watershed? Winter Wildlife: Secrets to Skipping the Winter Season

Winter in Pennsylvania can be a beautiful time of year, with thick blankets of snow covering the ground, icicles hanging from the trees, and constellations dancing across the ever-dark sky. Still, the short days and icy temperatures usually make me wish I could curl up and sleep the day away or take a long vacation somewhere warmer. In this edition of “What’s Up, Watershed?” I’d like to celebrate some of the members of our watershed that do winter differently — by skipping it altogether. Maybe we can take some inspiration from them as we all get through these next chilly months. 

1. MIGRATION

Because many plant and insect species go dormant over the winter, animals relying on them need to migrate south for the winter in search of another food supply. Pennsylvania is part of the Atlantic Flyway, a flight path that sees thousands of different migratory birds during the late summer to early winter months.

From the Appalachian Mountains in the western half of the commonwealth to the brackish Delaware River marshes further east, Pennsylvania’s diverse ecosystems allow a diverse group of birds to travel safely to their winter homes. This includes shorebirds including the Arctic Tern, songbirds and Woodpeckers such as the Northern Flicker, and even large raptors such as the Golden Eagle. 

Did you know that birds aren’t our only flying friends that use migration to thrive during winter? Of the nine bat species native to Pennsylvania, three migrate south for winter. Silver Haired, Eastern Red, and Hoary Bats are all tree-dwelling species — which means they aren’t protected from the elements and have to seek out warmer weather. 

2. HIBERNATION & TORPOR

The other six bat species in Pennsylvania have a different method for getting through winter: hibernation! During hibernation, body temperature, breathing, and heart rate all drop significantly. Hibernating animals can sleep for months at a time, only waking up to drink water and relieve themselves. Most animals prepare for hibernation by consuming large quantities of food over the summer and storing the extra nutrients in body fat. Groundhogs and Eastern Box Turtles are other species native to Pennsylvania that enter true hibernation. 

If you’re wondering why I haven’t mentioned bears, it’s because they aren’t actually true hibernators! Instead, Black Bears and many other mammals enter a state called torpor. It’s similar to hibernation, but much less intense. During torpor, their body temperature drops a little bit and they sleep for most of the day. However, they can still wake up to eat stored food, care for their young, and respond to danger. 

3. ICY EXTREMES 

Travelling somewhere warm and sleeping both sound like great ways to get through the winter, but other animals in Pennsylvania take their survival strategy to the extreme. One example is the Wood Frog. Like all amphibians, Wood Frogs cannot regulate their own body temperature. Unlike the other amphibians in

Pennsylvania, Wood Frogs don’t solve this problem by hibernating underwater to avoid the chilly air temperatures. Instead, they hide under leaf litter and let themselves partially freeze! When temperatures drop, a Wood Frog’s liver will send glucose to the cells in its body. This prevents the inside of the cell from freezing — similar to how antifreeze protects the pipes of an engine. Meanwhile, ice forms around the outside of the cells, creating a protective layer around the frog’s organs. These little frog-sicles start to thaw out when temperatures rise above freezing, making Wood Frogs one of the earliest members of the spring chorus.

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That’s all for this edition of “What’s Up, Watershed?”. We’ll see you next time, make sure to stay warm until then! 

Photos shown (top to bottom): Winter Coyote; Northern Flicker;  Grand Tetons black bear; Wood frog

Originally posted to PRC.org on 1/12/2026