A Little Bit More
Tree squirrels are so common that they're seen regularly by most of us, even if we live in an urban area. Although tree squirrels tend to be solitary within about a 1-acre natural home range, they are usually much more concentrated in urban and suburban locales. That population of squirrels you see on every tree in your local park is not reflected in the wild; squirrel populations become highly concentrated where handouts are regularly available.
Squirrels are rodents, members of the family Sciuridae (sigh-YUR-ih-dee). The word "squirrel" comes from the Greek "skiouros" or "he who sits in the shadow of his tail". Other family members include chipmunks, marmots (groundhogs), and prairie dogs. The three most widespread and best-known tree squirrels are the Gray, Fox and Red Squirrels although there are other species. Gray Squirrels prefer denser areas in extensive stands of mature hardwoods; Fox Squirrels prefer a mix of hardwoods and conifers (evergreens), interspersed with numerous openings of young shrubs and trees; Red Squirrels prefer coniferous or mixed conifer and hardwood forests.
Dens in tree cavities are preferred by all three species. Initially, a woodpecker's often excavated these cavities pecking, or resulted from a rotten area or broken branch. Cavities are usually found in mature trees, but agricultural and forestry practices often eliminate suitable nest sites. Any remaining tree cavities are useful only if the opening is located in such a way that the cavity won't collect water. And furthermore, a cavity must be small enough to prevent Raccoons (one of the squirrels' predators) from entering. No wonder good dens are in short supply! Lacking suitable den sites, tree squirrels make dreys that serve as housing and protection from the winter weather. Dreys are also constructed during the summer in some areas, but these are often rather flimsy and may be abandoned as winter sets in. As you walk in the woods, you may notice a drey here and there, but it's difficult to know whether or not it's currently occupied. Try using a binocular. Look for the entrance to see if there are any spider webs covering the entrance hole; if there are, it's a sure sign that the nest is not in use.
Activities
Survival Shelter
Objectives: See how a crude shelter can modify your microenvironment
Materials: Sticks of varying sizes and leaves plus an area for construction
When we think of a squirrel making a stick/leaf/grass nest, we may think it can't be very effective. However, a crude shelter can actually make the difference between life and death on a cold night, even for humans.
Students are often enthusiastic about this activity and will be eager to participate - cooperation is an important part of this exercise. If you don't have enough materials to construct your own shelter, look at the diagrams of what the shelter consists of and bring in from home what you'll need (be sure to bring in more than you think necessary).
If space and/or materials to perform this activity are not available, you could do this in miniature. It will be fun for the students to use very small sticks etc. to create their own shelter on a tabletop by scaling down all of the "ingredients" for construction. They'll need a little creativity to come up with the necessary materials, but then, kids are good at this.
Key Concepts
Behavior and Regulation, Structures and Functions
Questions
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Posted by susan hardaway on August 06, 2006 at 01:05 PM
Q: There is a critter that is a type of marmot or groundhog. I thought there were differences in the tail in order to correctly identify what is burrowing under the fence. My neighbor says its a groundhog, but I thought there might be a slight differnce.
A: The Groundhog is definitely a kind of marmot, in fact its scientific name is Marmota monax. The name "Groundhog" is merely a common name for this particular species of marmot that is the easternmost representative of this group of rodents. The differences in the marmots is more one of range (where they live) and a bit of coloration - they all look pretty much alike. Hope this helps.
Posted by stan imada on March 28, 2006 at 05:38 PM
Q: is it true that saliva is used to glue leaves together in a squirrel's drey?
A: That's a new one for me - I've never heard about this. To the best of my knowledge, squirrels simply interweave branches/leaves together for their dreys and saliva has no part in its construction. You may have heard about swifts (a kind of bird) using their saliva to construct nests, but I don't think any mammals do this. Thanks for asking.