Chipmunks, what fun critters to watch! Their tiny striped bodies darting from place to place seeking food with senses peaked to detect any sign of potential danger. If you sit nice and still they will run right up to you in curiosity. If you have a clam sense about you they many times will run right up and sit on your leg like it is a log they found to perch upon while their teeth whittle away a seed casing.
I think most people here are familiar with the sight of chipmunks and perhaps even mark them up as a common sight in both yard and park. But how much do you know about them I wonder. This is the case with most people and most critters of the outdoors. Even though an animal might be a common sight does not necessarily mean that a person of this modern age knows much about them. It rather goes along with my last article on Attention Spans.
With that in mind let me lay out a few things about our tiny furry friends the chipmunk and shed some light on the topic. Let us see how much you know about them, shall we?
Chipmunks are of the rodent family and so before I begin with the chipmunk I will talk a little about the vast rodent family, Rodentia. It is important to state that the rodent family of animals is the largest order of mammals in the entire world. Zoology states that the rodent family makes up more than half of the total mammalian species with around 3,000 rodent species included. In North America alone the vast diversity of rodents is quite astounding. From the up to 90 pound (40 kilos) beaver all the way down to the smallest of mice weighing in at less than an ounce (<10g). Included in the rodent family are squirrels, beavers, chipmunks, mice, rats, marmots, prairie dogs, groundhogs/woodchucks, gophers, lemmings, voles, muskrats, porcupines, and nutria here in North America. Notice rabbits and hares are not listed? This is because they are members of the Lagomorphs family and not the Rodentia family. Picas also are part of their own family, even though they look sort of like a rodent. They belong to the Ochotona family rather than the Rodentia.
What makes a rodent a rodent? Three main characteristics are used to generally define an animal as a rodent.
- Rodents only have two incisors in the front and then molars in the back of the mouth, but no teeth between which creates a large space (rabbits and hares have 4 incisors, two in front and two behind them)
- Rodent incisors do not stop growing
- The incisors only have enamel on the front side, leaving the back of the teeth unprotected and soft, allowing the animals to shave them down since the continually grow
If the rodent does not constantly chew on things to wear down their teeth, the teeth will grow and grow, eventually either starving the animal, since they would prevent the animal from closing its mouth or eating, or the teeth would grow back into its skull and kill it.
Many rodents are nocturnal, but some prefer diurnal activity, like most squirrels. Quite a few remain active and scurrying all year long throughout all seasons. However, there are some who hibernate during winter or go dormant in extremely hot summer locations. Due to their incredible population and their average size, they are a powerful food source for a great many predators. The Rodentia family compensates for heavy predation losses with a truly remarkable reproductive prowess that cannot be found in any other mammal.
Seeds, nuts, roots, fungus, insects and arachnids are the primary food source for rodents, which help keep the insect population down. If we removed all rodents from the world we would lose all of our food sources to insects in a matter of a few years, at most.
Now let me return to chipmunks.
Chipmunks are actually squirrels (Sciuridae family). Of the nearly 275 species of squirrels around the globe, the 22 species of North American chipmunks are part of that total species number. Of the 22 chipmunk species, all but one lives in the western expanses of North America. Only one, the Eastern Chipmunk, lives in the eastern section of the continent. Of course the western species look so similar, for the most part, that it can be extremely difficult to identify who is who in the field. Typically the Eastern Chipmunk is larger than the western species, though in many western states people refer to chipmunks as “mini-bears” and for good reason. They are voracious eaters! The average weight of chipmunks spans 1-6 ounces (28.34 grams – 170 grams).
The primary activity of chipmunks is searching for food, gathering food and carrying it back to their dens for storage. This completes the majority of their daily regime. Seeds and nuts are their primary food source, though they will eat many types of insects as well. They are omnivores, not herbivores. This also means they will eat fruits, eggs, small birds and mice and grain as well.
Not only do chipmunks help control insect populations, but they also help to spread seeds of plants, thereby assisting the spread of vegetation, including trees and fungus of which some are crucial to tree survival, like the mycorrhizal.
All chipmunks have a fur-lined cheek pouch in the space between their two incisors and the rear molars to stuff and carry food in. Obviously they cannot carry handbags with them, so they had to evolve in such a way as to be able to carry large amounts of food from source to den. The cheek pouch was the answer, and when stuffed full with food, I think adds quite a bit to their cuteness and humor.
Most chipmunks enjoy forested regions to call home. They rely on trees quite a bit. Trees supply shade, shelter, insects, nuts, seeds, birds and mice, fungus, protection, bedding debris, insulation debris, aeration and thus easier digging soils. Nevertheless, the chipmunk can be found in forest and desert, mountain and field alike.
They typically have a territory of about ½ to 2/3 or an acre in size. Their burrow is contained within that territory and the adult chipmunks only really defend a 50 foot radius around their den site, no matter how large their total territory is. It then becomes easy to find the burrow of a chipmunk by watching where they are chasing other chipmunks away from.
With pale to dark colored fur designed with black and white face stripes, four pale body stripes spaced by five dark stripes, they are wonderfully camouflaged for a wide variety of terrains, but especially field and forest. Observation has shown that typically the more humid the climate, the darker their color and the drier the climate, the paler their colorings are. Of course by observing vegetation colors in humid and dry climates, we can see why they have those color variations.
When they take a break from gather and storing food, they will mate. Typically mating occurs in early spring, but with some species, like the Eastern Chipmunk, the first year females will not mate until mid summer. Yet there are a few western species that will occasionally produce one litter in spring, after a standard 30 day gestation, and another in early autumn. An average of 3-6 blind young are born in each litter. The young are self sufficient within 8 weeks of birth, though may hang out with siblings for company a while longer.
Chipmunks dig burrows, or borrow them from other critters who abandoned then tunnels. Usually the burrows are about 3 feet deep and 2 inches wide and 10 feet long. They can tunnel into the earth, hollow logs and old stumps as well as up in the hollows of trees. Within their tunnel system they will have debris filled sleeping chambers as well as food storage chambers, which can be quite numerous, especially in cold climates.
The chipmunk is a hibernator because they do not built fat stores for insulation. But even though they are considered a hibernating mammal, they are light hibernators as opposed to a deep hibernator like groundhogs. Even though in cold climate winters it will hibernate to conserve energy, it will awaken every few weeks or so to feed on its bountiful food cache. During hard winters following poor crop yield, the chipmunk many hibernate most of the winter, but in high food yield years they may scurry from food chamber to food chamber quite a bit throughout the winter months.
Interestingly reports are coming out stating chipmunks in the southern regions are tending not to hibernate many winters because of the trending warm spells in select regions. Of course “Global Warming” is said to be the reason, but I think most of us here in the Den know that is bogus. As the globe shifts around the climates also shift and we are in a stage of the earth’s climate patterns that produce huge fluctuations in extremes. As I have said before, this can dramatically affect animals and their habits. In regions where the winters have been overly warm for a few years (of which most have been then plunged into abnormally cold winters), the chipmunks were observed not to go into hibernation, but remain active all season. Another observation of the Fordham University was that the chipmunks that did not hibernate were very likely to die by the spring, where as hibernating chipmunks had around an 87 percent survival rate after winter.
Since the wild living chipmunk’s lifespan is only between 2-3 years, the hibernation phase seems vital to its rather short longevity. While in hibernation their body temp can plummet to the temp of their burrow, which can be down into the 40’sF (4C). Their high typical heart rate of around 340-360 BPM can dive to a mere 5 BPM.
Chipmunks, being rodents, are very sensitive to alarm calls of birds and other animals. They remain very astute to their surroundings and can be seen darting like lightning to the nearest cover or lookout perch at the slightest potential disturbance in the local energy. However, the warning goes two-ways. Since chipmunks and other squirrels are known to eat the occasional bird egg, if given the chance, many ground-nesting birds will avoid setting up home where they hear the calls of chipmunks and other squirrels.
Weasels are the chipmunk’s largest predator and are built to enter the narrow burrows while seeking a meal. Thus the chipmunk will always have multiple entrances and exits in their tunnel system for emergency escapes. Of course in hot climates many snakes will hunt chipmunks and in all climates the hawks have a good eye for the chipmunk as food also. Bobcats and domestic cats, foxes, coyotes, fisher cats, and quite a few other predators also enjoy dining on chipmunks.
Lastly the chipmunk has four front toes and five rear toes. They are considered to be bounders as the run and leap across the landscape. A bounder jumps ahead landing with its rear feet placed before the front feet in a square pattern of four distinct tracks spaced evenly apart.
The chipmunk is a wonderfully fun animal to watch and marvel at. Their cute and entertaining behaviors can teach us much about energy movement, gathering and storing for future use. Diligent productivity for the promise of tomorrow, without neglecting the absolute of the NOW, the moment and all its finer intricacies, intimacies and nuances.
So how much did you really know about this animal neighbor?