Chipmunk
Photo courtesy of borealforest.org

Landscaping with Chipmunks

   

"My friends all know that I am shy,
But the chipmunk is twice as shy as I.".

-Ogden Nash
(1902-1971)

This complaint appeared on a gardening bulletin board: "We have an unusually large invasion of chipmunks this year, too many to trap & release. How can I get rid of all these chipmunks? Should I get a cat?"

Golly. I would love to have an "invasion" of chipmunks, but there are cats galore in this neighborhood, so will have to settle for the one young unmarried squirrel that has taken up residence, is frequently on the deck, & who'll undoubtedly have a mate with him eventually.

As a kid I lived some while on a thickly wooded property that adjoined the far back of Saltwater State Park, & we had lots of chipmunks scattered thinly throughout those woods. But the area was in the process of being severely developed until the park was hemmed in by housing projects. Soon the the only chipmunks ever seen were whatever remained after cats killed them. In time the beautiful little chipmunks completely disappeared, never again to be seen in or around Salt Water State Park.
Chipmunk
(Another query came in: "Don't chipmunks cause structural damage to the foundations of houses? Don't they nest in the walls & chew up wiring? I've got them near my house. How do I protect the foundation?" So to go alongside my long chipmunk article, here's the short answer:)

Chipmunks rarely cause structural damage of any kind, but people selling pest-control services & products (most of them worthless) do everything they can to induce hysteria, as it helps their business.

If you have a basement, then chipmunks have no way to burrow under your foundation, as they don't dig deeply. They're more likely to burrow under a patio, or under the sort of flat thin foundation poured cheaply upon which to sit a doublewide.

So first be sure there really is a threat. If there is, chipmunks can never get through 1/4th inch wire hardware cloth, & since their burrows aren't deep, it doesn't take a lot of trenching to install a barrier around any foundation you're worried about.

They need "cover" to leave their burrows so if you don't have shrubs growing right up against the foundation, chipmunks usually won't consider that a good place to start burrowing, as their entrance/exit will be too exposed to predators. They're easily controlled even by an outdoor cat, as they're rather too easy to catch.

You can provide them with a preferred habitat located where you want it, a very rocky rock garden for instance with plenty of stacked rocks with places to begin a natural burrow well protected from cats and other predators but easily tunneled by themselves, flanked with shrubbery that does not lead to any patio or thin foundation.That will become their perferred habitat.

Placement of birdfeeders can also control where chipmunks hang out to gather what falls on the ground. Bird feeders might need to be further from any foundation they are interesting in digging under.

It was so sad to see them go. When there were adolescent chipmunks about, they were easy to trick into a box with a tasty bait, & when you grabbed them, the young ones would struggle but rarely bite. Older chipmunks that might've bitten couldn't be caught; weanlings were harmless, naive, & trusting.

I kept one for a few days & though wild-caught it would ride around on my shoulder or hide in my pocket. I made it a little choke-collar with a slim gold chain & pinned the loose end of the chain to my clothes. The chipmunk could slip out of the collar with great ease & was not at risk of getting choked by its adhock leash. After a few days of having it as a nice little pet, it got down on the ground while I was carrying it outside, then was off like a dart, heading back to where it belonged.

It's true chipmunks don't have much of a chance around cats, unlike squirrels which are big even as adolescents, difficult for a cat to overcome. Squirrels are even known to amuse themselves by playing "ha! you missed me!" games with dogs & cats, posing as if vulnerable & intentionally staying put until making its get-away at the last possible micro-second.

Not so for chipmunks. Adult chipmunks do learn how to avoid cats, but young ones are quite stupid about it. Throughout the natural ranges of various North American chipmunk species, they vanish out of suburban settings for no other reason than cats.

Squirrels & chipmunks are highly territorial & except when a female is raising kits, there would rarely be more than one or two in a given area at any one time. The male does not ordinarily help raise kits, although there are some enticing field observations that suggest it might sometimes happen; usually the male has his territory & hobbit-hole separate from the female. They tolerate each other in overlapping territory only when the female is eager to mate.

Chipmunks breed twice a year (the Least Chipmunk breeds oftener). So there will be adolescents appearing in late spring then again in autumn, but when they are two months old the mother beats the living daylights out of them & they move away or die from mom persistantly badgering them to leave.

Chipmunks have tighter overlapping territories than squirrels, & produce a larger number of young each year; so there could be a few more chipmunks encountering one another in a given area, chirping warnings at each other to keep their distance; & there could be a few sets of adolescents with overlapping parental territories, but only for a brief time, because they must eventually find their personal ranges or be continuously harrassed by adult resident chipmunks, living a life devoid of safety until a predator gets them for lack of a personal burrow.

Squirrels sometimes live as aggressively territorial couples, but adult chipmunks tend to be solitary outside of the mating season, as are woodchucks, & they are intolerant of rivals. So the complaint that there are "too many to trap live" does not sound normal.

If someone trapped one or two, drove them to a park four miles away & turned them loose, they would very likely come right back. They're that territorial. And having enjoyed the trip & being slow learners compared to squirrels, they'll go in the trap again if it has something tasty in it, & they'll be released in the park, & they'll return yet again.

Some people trap & release the same chipmunk time & again, thinking there is an endless supply. Their territoriality is such that they will return from as far as ten miles away, so would have to be taken very far away to a woodland or meadow environment before they'd have no chance at all of finding their way home. This compares to a rat or mouse which can return from three miles away (turning smaller rodents loose on the back forty or down by the creek is barely a one-day jaunt back to the house).

I saw an advice page that said to turn the chipmunks loose five miles away & to make sure they have no water resources in your garden. Exactly the wrong advice on both points. They'll return from five miles within a few days, & they'll attack fruits if there is no standing water.

Repellants are pretty much useless but if you find the burrow's main entries & repeatedly muck up the burrows with cayene pepper or predator urine, the resident chipmunk will probably be forced to move eventually, unless really hemmed in by other "taken" territories, meaning there's no place to move to that wouldn't get it attacked by rivals for space. So they have to suffer your abuses as the least of many nuisance variables in the lives of littler chippers.

When caught & released so far away they cannot get home, they are apt to find they are in territory already divied up between established chipmunks. As strangers they will be at risk of being harrassed to a miserable death. Gardeners who just can't tolerate wildlife may actually be less cruel to just shoot the critters & not pretend trap & release is humane.

This can vary, so talk to animal control about local rules on release. In some places the chipmunk population is already minimal (due to cats, or because habitats have become separated islands, or because areas of woodland reclamation haven't yet attracted all the suitable species) so there may be an area where release would be beneficial by re-introducing a local species where it belongs but has previously died out.

Because of their territoriality they have an imperative to "make do" in their allotment. If a garden produces no berries or grains or nuts to gather, they'll go after flowers or whatever. But they take the route of least exercise & do not create endless excessive stores of foods like squirrels do.

So pandering to chipmunks a bit can usually control where & what they harvest in one's yard. They can even be induced onto porches or laps, especially when adolescent, if that's the easiest way to get food. In rough times they'll dig bulbs if that's all there is, but it's not their preferred food, & even their tunnelling is usually restricted to the area around their burrow, so their diggings do little or no harm to gardens.

A single adult female can have two to six chambers along tunnels five feet to twenty feet, though they excavate slowly & it would take years for a chipmunk to have more than a tiny burrow. Large burrows are usually generational, with successive mothers adding chambers. Males don't extend burrows as far.

Unlike surface-burrowing moles, chipmunks tunnel one foot down before connecting chambers with horizontal tunnels. They do not require their tunnels to be too extensive since they spend much of the day above ground, & do not usually disturb bulbs or anything else since their tunnels run underneath root systems which chipmunks don't like to excavate at all, being path-of-ease animals at heart.

Obviously the specific environment they're in defines how true these generalities will be case by case, but as a rule their burrows are harmless to a garden & their population is restricted by their own aggressive defense of their turf against intrusions from rival chipmunks.

So I was curious why the gardener on the bulletin board disliked these particular chipmunks. Depending on what someone is growing, chipmunks usually are not very pesky. Unlike squirrels they're not smart enough to get around protective barriers on bird feeders, & so merely clean up only what falls to the ground. They harvest very little from gardens, though in hot weather they will chomp into eggplants or tomatoes just enough to quench thirst, but will not do even this if there is a garden pool or birdbath they can reach.

They're diurnal, so easily seen at their amusing antics, are disease-free, & the adolescents are very trusting in approaching humans. They harvest berries in summer & grains & nuts in autumn & bitter berries in winter if not hibernating, but do this to a far lesser degree than do birds. If there are no decent food resources they might resort to leaf buds or newly seeded shoots in the early spring garden, but would quit if there was anything decent to eat, & even at their worst don't usually get much. They do some garden excavating for the sake of a burrow, but not to dig up tubers, & at their most industrious they're still not very aggressive at tunnelling. In all, they should be easy to live with.

To encourage chipmunks one has to have an area that is cat-proofed or where they can create a burrow close enough to escape at the earliest appearance of a cat or hawk. Though they can spend a lot of time up the sides of trees, most chipmunk species are rather ground-oriented near their burrows. They like a spot with piles of rocks, so that digging predators can't get at them. They will also make a burrow in a lumber pile or partially rotted log, or an old stump the rotted roots of which provide path-of-ease burrow possibilities.

Their burrow entrances are tidy & hard to spot, except the large ground-squirrels which prefer grasslands & build obvious dirt barrier around the burrow entryway in any exposed area so as to see into a distance. As the ground squirrel is a loner & fights off rivals, even this fellow can be integrated as an "interesting addition to landscaping" as the Michigan State University gardening & animal data base sweetly put it. But as to the small chipmunk, it will have a tiny invisible entrance at the edge of fallen timber, lumber, stumps, or amidst rocks.

Really it is best to consider them an integral part of the garden if you're lucky enough to have them, & whatever little conflict with gardening occurs, deal with it by rewarding them to stay in the woody-shrub portion of the yard where they can do no harm. This would mean providing a ground level birdbath so they don't have to seek tomatoes & eggplants for water, a feeding station of peanuts & crushed corn & sunflower seeds so they don't have to settle for budding leaves or sprouts, all in eye-shot of a comfy window so you can watch them at play as you would the birds.

   



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