Fair Weather Friends

A lot of the excitement goes out of my life at the end of each autumn.  You see, this is the time of year when the chipmunks retire to their winter dens.



Photo compliments of The Animal Diversity Web (online). Accessed November 17, 2011 at http://animaldiversity.org.

 During the warmer months of the year, there is nothing that gets me more worked up than the squeak and shuffle of a chipmunk navigating the edges of our yard.  They always announce that they are about to run the gauntlet from the oak tree in the front yard to the retaining wall at the back of the garden.  This noise could be interpreted as something akin to taking a deep breath before diving into a cold lake.  With a piercing "CHIP", they begin their frantic scurry along the fenceline, behind the rosebuses, and into the garden, with me hot on their heels.

Personally, I think they love the thrill of the chase.  I am not particularly dangerous to them, as I can never catch the quick little rodents.  They are just using me to add a little rush of adreneline to their days.

I will not meet the little striped rascals again until next spring.  Chipmunks are not true hibernators, but they do enter a period of winter torpor.  They stay in their dens, snug and protected from the elements, throughout the harsh winter months.  They sleep most of the time, only waking occasionally to munch on stored nuts and seeds.

Their relatives, the groundhogs (also known as woodchucks),  are true hibernators.  Woodchucks dig special wintering dens, well below the frostline, where temperatures are relatively warm and stable.  They eat frantically throughout late summer and fall, building up a layer of body fat that will sustain them throughout the upcoming winter months.  When the time comes, sometime in late fall, they snuggle into their dens and fall into a state of inactivity, characterized by lowered body temperatures, dramatically slowed breathing, and decreased metabolic activity.  They will remain "asleep" until the end of winter (which, of course, they can predict)!

Another group of amazing hibernators are the frogs, such as this tree frog.

The tree frog will overwinter in shallow mud, under bark, or hidden beneath rocks or logs.  Most of their bodily fluids will freeze solid over the cold season.  However, a special chemical produced by their livers, similar to antifreeze, keeps their internal organs from freezing and allows the frog to "thaw out" in the spring. 

So, along with the birds that fly south during our winter months, we also need to say a temporary goodbye to the animals that use techniques like hibernation and winter torpor to survive the cold.  We'll see them again in the spring.  In the meantime, I am glad I have a thick fur coat to keep me warm.  I can't wait for another season of playing in the snow!

What other Iowan animals seem to "disappear" during the winter?  Many of them are still out, enjoying the last bit of warm weather during this extended autumn.  Get out to our parks and try to get a last glimpse of chipmunks, groundhogs, skunks, bats, ground squirrels, and other animals that wait out winter in the security of their warm dens.  Send in your photos with your comments!