Thursday, December 17, 2009

What do they do for Christmas?

Nature Watch
By Susan Benson,
CNHM Director of Education

While I watched students in a classroom writing their letters to Santa, I began to think about how different animals spend their Christmas. Where do the birds go? What about the frogs or turtles? Are the black bears already hibernating? What kind of “Christmas” do they have?

Where do some of the birds go for Christmas? For this answer, I had to go to my favorite bird field guides. The common loon leaves our lakes to enjoy the eastern and gulf coast, as well as the south-eastern part of the United States. Banded great blue herons from Canada have been found in Mexico, Honduras, Cuba, Colombia, Venezuela, and Ecuador’s Galapagos Islands. Some of my favorite forest-loving birds have just the right idea – red-eyed vireos end up in the western Amazon, hermit thrushes in the Bahamas, Guatemala, or El Salvador, and the black-throated green warbler in the Bahamas, Cuba, Jamaica, or Panama. The northern oriole heads to central Mexico or northern South America. Finally, the winter wren (how does it get that name anyway?) winters in the southern United States.

If we take a look at bald eagles of the Great Lakes region, they do not always migrate, though these resident eagles may travel significant distances in winter to seek food. Ruffed grouse stay with us, growing fringes on their toes in the winter to act like natural snowshoes and spending cold nights using the snow as insulation – imagine using the snow to stay warm. Next we can look at the resident bird that carries a bit of Christmas red color, the pileated woodpecker. These birds make deep, oval excavations in trees to find ants, especially carpenter ants, and wood-boring beetle larvae. These woodpeckers apparently have the “spirit of giving” year-round, as their large excavations often become feeding stations for other woodpeckers, wrens, or other birds.

Frogs have an interesting Christmas. Wood frogs, for example have no heartbeat. They do not breathe. Their blood does not circulate. Their nerves barely register electrical impulses. They are essentially frozen solid, yet their vital organs are not damaged. Spring peepers, gray tree frogs and upland chorus frogs also may freeze and thaw several times during the course of a winter. How do they do it? The answer is antifreeze. When ice begins to form on a wood frog’s skin, the frog’s liver releases a high level of blood sugar, enough to fill the blood vessels in all vital organs, creating a type of antifreeze. Other frogs will burrow into the soil or a lake bed to keep from freezing. Leopard frogs sink to the bottom of a water body, where they sometimes unfortunately become food for a fish.

Where do turtles go in the winter? All but one of Wisconsin's eleven turtle species spend Christmas under water. A few turtles bury themselves while others remain motionless on the bottom. Some scientists believe that they hibernate, their blood changing to function like antifreeze, with their body temperature dropping to only a few degrees above freezing. Other scientists believe that they don’t hibernate, but are semi-active, although this activity can take a toll on their body reserves.

When do black bears go into hibernation? Do they nestle in their beds for a long winter’s sleep? Technically, bears go into torpor, which is a state of reduced metabolism from which they can be awakened. Male black bears don’t always go into dens, sleeping right on the ground, or under downed treetops. These males can be more easily aroused from their “winter’s sleep.” When you add the fact that there are a lot of humans moving around in the forest during our fall hunting season, and combine it with the current feeding and baiting of deer or other animals, it is possible to see signs of bears even through November. The latest I have seen bear tracks in the snow is December 13, although most female black bears can go into torpor as early as October first.

As I wrap my presents, enjoy my lit tree, and huddle inside my warm house, waiting for a holiday season, I again find a renewed sense of wonder at the natural world. How fortunate we are to be able to enjoy this variety of wildlife all year round, no matter what the season or conditions in which we find ourselves.

For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at to learn more about exhibits and programs.

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