How do they do it? Winter survival strategies of local wildlife
By Cathy Meyer, Naturalist, Monroe County Parks & Recreation Dept. See the rest of our Winter 2015 Twig newsletter here.
As the days grow shorter and the nights get colder, we retreat into our homes and turn on the furnace. Watching the birds at the feeder, hot cocoa in hand, we might wonder how the animals fare out there.
Some critters don’t maintain a constant body temperature and cannot stay warm enough to keep from freezing. This includes amphibians, fish, reptiles, insects and other invertebrates. They can survive with little food but if they get too cold they will die. A few insects migrate and leave the colder climes for places that stay warmer, but amphibians, fish, reptiles, and most invertebrates must find protected areas to overwinter.
Frogs and turtles may burrow into the mud in lakes and ponds. Snakes find denning areas in rock crevices. Insects and other invertebrates may burrow into the soil, or hide under loose bark or in hollow plant stems. While many animals seek shelter where the temperature does not fall below freezing, some frogs and insects generate their own anti-freeze to stop ice crystals from forming in their cells, preventing the tissue damage that would otherwise kill them. Many insects overwinter in particular life stages – as eggs, larvae, pupae, or adults. On a warm winter day it isn’t uncommon to see moths flying around. Sometimes bats will emerge to eat them.
Birds and mammals maintain a body temperature higher than their surroundings in winter and must find enough food to fuel their higher metabolism. Most of Indiana’s mammals are active all winter and have adaptations such as warm fur, feathers, or extra body fat. Other than bats, few of our mammals truly hibernate. Many, such as chipmunks and skunks, remain in underground dens or other shelters when the weather is very cold and only come out on warmer days. Some animals, like the chipmunks, have stored food to get them through the winter. Beavers anchor branches under the water so they can feed even if the water freezes above them. Squirrels and blue jays bury nuts.
Many birds, especially the insect eaters, migrate south. While hummingbirds can enter a state of torpor, most of them migrate. Migration as a survival tactic is triggered by day length, not temperature fluctuations. Even so, migration itself has high energy costs and can be very dangerous.
Winter is a great time to visit a Sycamore Land Trust preserve to look for signs of animal activity such as tracks in the snow or mud, scat, chewed nuts, deer rubs, woodpecker holes, and beaver work on trees. Your chance of actually seeing the animals is greater because there are no leaves to block the view and animals may be more active as they search for food. Find out who your neighbors really are!
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