Friday, December 14, 2012

Cirque de Squirrel

It's a good thing you know what squirrels look like, because I don't have a picture of a squirrel for you!  I wanted to write about them this week, but when I went to take pictures, they were gone for the day.  That's OK, though, because there is plenty of squirrel evidence visible in our outdoor classroom.  If you visit and don't see actual squirrels, look for clues instead.

Squirrels are messy eaters.  They unwrap their food, eat what's inside, then drop their food wrappers all over the place.  If you walk around the outdoor classroom and look down at the ground, you can see their food wrappers (complete with squirrel teeth marks) all over the place!  (You may notice that humans are also sometimes messy eaters - I picked up several human food wrappers out there this week.  Somehow human food wrappers are less adorable than squirrel-chewed walnut shells.)
Evidence of squirrels.
Another visible sign of squirrel activity is squirrel nests.  If you look to the top of the magnolia tree in the front yard of the beautiful building next to our classroom, you can see a squirrel nest.  Do you see it in the picture below?
Can you see the squirrel nest in the top of this tree?
Here is the squirrel nest a little closer:
Squirrel nest in the top of a magnolia tree.
Squirrels are probably the easiest topic for me to make interesting, because just about everything squirrels do is either hilarious, cute or annoying.  Here are a few fun things you might notice about them this time of year if you stop to watch them for a while.

1. Acrobatics.  Squirrels climb up and down all sorts of surfaces.  They are the only mammals that can climb down trees face-first, which they do by turning their back feet around as they descend.  Squirrels chase each other on mad dashes through the tree tops, often making great leaps from one tree to another like circus performers on a trapeze.  They also have a great high-wire act - squirrels commonly run across electric and telephone wires as easily as we run on sidewalks. 

2. Nest design.  Squirrels make extremely well-insulated nests in crevices in buildings or trees or constructed in tree branches or on top of bird nests.  They layer their nests with feathers or thistle or dandelion down (those feathery parts of the seeds).  When their nests are made of leaves, they can add layer after layer of leaves to make a hollow ball for sleeping.  The layers of leaves keep the rain out and the heat in.  Since squirrels don't hibernate, they need to keep their body temperature warm all winter, so their nests are important for keeping them warm at night, just like your nest, er, I mean, bed.  Look for squirrels carrying leaves or other materials to build nests next time you see one.  (You can try out a leaf nest for yourself.  If you layer about 50 tightly-packed leaves carefully over a balled-up paper towel then sprinkle water over the top, the paper towel is unlikely to get wet.)

3. Variety of Behaviors.  Squirrels are generalist feeders.  We always think of them as eating only nuts, but they also eat tree bark, berries and seeds.  Generalist feeders tend to have a much wider variety of behaviors than animals that eat only one thing.  Generalists must be curious about new food sources and adapt their food searching to a variety of challenges, which means their brains must be flexible and able to improvise.  Nothing against cows, but compare the variety of behaviors of squirrels to cows, and you can see what I mean.  Try making a list of all the things a squirrel does next time you see one.  I'll start: chase, dig, search in the grass, make a loud alarm call, climb up bricks.....

4. Problem Solving.  If you've ever had a squirrel figure out how to access the seeds in your bird feeder at home, you have seen the evidence of squirrels' ability to solve problems.  Once they locate a food source or nest site, they will try many new strategies to succeed in their plans to eat or build a nest.  Notice how ingenious this squirrel is at getting to what he wants despite human attempts to keep him out of the bird feeder.  Squirrels are an inspiring reminder to try many different strategies to succeed at a task.

5. Memory.  Squirrels have an unusually good memory for where they leave food.  They store food for the winter in a method called scatter-hoarding.  It's the opposite of how humans store food - all in one place in the kitchen pantry.  Squirrels leave little patches of food buried or hidden in hundreds of places, and they remember where they leave the food (they don't find their stashed food by smell - they find it by memory).  Scatter-hoarding is risky because squirrels can't guard all their food at once.  However, if their food is discovered and stolen from one location, they still have hundreds of backup locations that are unlikely to be raided.  Look for squirrels burying their food - the squirrel is almost 100% likely to come back and dig up that food later in the season. 

6. Deception.  I'm not condoning lying, but it sure is amusing to watch squirrels lie!  If a squirrel knows it is being watched by another squirrel, it will not actually hide its food.  Instead, it will pretend to hide the food by digging a hole, pretending to drop in a nut, and covering up the hole.  The watching competitor squirrel will be fooled, then the squirrel will go and hide the food in private so as not to reveal the hiding place.  It is easy to verify if a squirrel has lied.  Next time you see one bury a nut, go check and see if the squirrel has actually done so or if it has fooled you too.

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