Last Thursday, Rachael Rost, education specialist at the Topeka Zoo, ventured into the 20-degree cold and presented a terrific program at the Library she called, “Winter Adaptations.”
Have you ever wondered how wild animals survive during the winter, a time of limited or scarce food sources?
To help us understand, Rachael explained biological processes and introduced some scientific terms.
We learn in elementary school that some mammals hibernate in the winter. During hibernation body temperature falls so low that it’s only a few degrees above the soil temperature. The animal wakes up every few weeks to eat stored food and release waste. But did you know only small mammals, such as the hedgehog, truly hibernate? This means bears are really just “winter lethargists”–they lower their heart rate and become inactive, but their body temperature doesn’t go low enough to be in a state of true hibernation. They are basically in a deep sleep called torpor but may awaken to fend off an intruder.
Some insects such as ants and termites find a protected place (anthills or mounds) to spend winter. Other insects practice diapause, which is basically insect hibernation. Growth is actually suspended during this period. Have you ever seen ladybugs group together to diapause in your house during the winter?
Many birds, such as snow geese, travel south (or migrate) to warmer climates for the winter. Rachael brought an Eastern Screech-Owl from the Zoo and explained that not all birds, such as the Screech-Owl, are migratory and instead adapt to their existing environment to survive. In warm weather Screech-Owls feed on insects and bugs. In the winter they feed primarily on mice. The Screech-Owl’s process of switching food sources and its ability to survive on this changed diet in winter is an example of a winter adaptation. Think of your backyard birds, too, during January and February and set out wild bird seed and clean water for them.
Rachael brought a Red-eared slider, a familiar turtle at Kansas ponds, lakes and wetlands, and described how cold-blooded creatures (also known as ectotherms) get most of their heat from external sources, such as the sun or heated stone. Sliders are able to lower their metabolism and can spend months underwater. In fact, they are able to hold their breath for 3-4 months but also acquire precious oxygen around them to survive. Rachael explained that “cold water traps and holds more dissolved oxygen than warm water.” This is how aquatic turtles are able to survive our cold Kansas winters.
We were introduced to a large male American bullfrog, a cold-blooded amphibian that resides in Kansas. The bullfrog’s skin is semi-permeable and he breathes in oxygen through his skin. Similar to the slider’s behavior, in the winter he will bury in the mud at the bottom of a pond or lake and will absorb oxygen from the water through his skin to survive. So, the next time you see a frozen pond or lake, think about what is happening beneath that frozen layer!
Reptiles such as snakes go dormant in winter (lower their body temperature and energy needs) and spend the cold months in a den where they can stay warm. Did you know a hibernaculum is a sheltered place where animals, such as a group of snakes, spend the winter? In the summer snakes estivate, which is another form of dormancy, and will seek shelter in a cool place during extreme heat.
Rachael brought several different fur pelts to pass around. We touched otter fur and the incredibly thick white fur of the Arctic fox. The fox’s fur turns white in winter for camouflage, a change from a grayish color in summer. He has special footpads that provide good traction and keep his feet from freezing in the snow and ice, another example of an adaptive trait necessary to survive in an extremely cold environment.
Check our catalog for children’s books about animals in winter. For adults, Bernd Heinrich’s Winter World is a great read.
The next Zoo Animals program at the Library will be at 4:00-4:45 p.m. on February 6, featuring the Great Horned Owl, Library staff’s adopted Zoo animal!