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Keeping the Peace Between Gardeners and Chipmunks
When I first moved into one of Washington, D.C.’s Virginia suburbs, shrouded with heavy woodlands, I was thrilled by a little flash of energy that rocketed past me one day as I stepped from house to backyard. Was that a chipmunk?
Was I happy to see it?
The years have passed by since then, as they make a practice of doing, but I still get a thrill out of seeing chipmunks in my yard. I am especially pleased when one of them takes a position atop the highest point in the yard and stands there like the monarch of the mountains surveying its domain. Nothing is cuter to my eye than a chipmunk. I love it that the hair along the eastern chipmunk’s sides and back looks blue—I don’t see many blue mammals. I wish I could watch chipmunks at length and learn something about their lives, other than that they are very jumpy little creatures, bolting away at the slightest provocation. A habit, however, that probably serves well a creature that is food for practically every predator out there.
I didn’t know until recently that some gardeners don’t like them. Apparently, chipmunks sometimes eat bulbs and ornamental flowers. Personally, despite the pleasure I get from seeing blossoms in my yard, I would just as soon grow chipmunks as nonnative ornamental plants. As for native plants, they should be adapted to chipmunks, given that one of the little rodent’s most important ecological roles is the spreading of seeds and, therefore, the spreading of plants, including those that produce berries—a benefit for many species.
Let’s chat a bit about chipmunks, about what they do and about what you can do to defend against them if they trouble your garden.
Evolution must favor chipmunks, because it has made 21 species of them in North America. All but one of those species belongs to the genus of western chipmunks. The remaining loner is the eastern chipmunk, the denizen of my backyard, found across much of the eastern and central United States and Canada.
As a rule, chipmunks live in woodlands throughout much of North America. Relatives of tree squirrels, prairie dogs and various other ground squirrels, they are the pipsqueaks of the squirrel family—about the size of a mouse. Western chipmunks tend to be smaller than eastern, about 2 ounces to the eastern’s 4.5.
Immature forests and forest edges provide chipmunks with the shrubs, fallen logs and other items the rodents use for cover. Though they do climb trees in search of food, generally they forage on the ground for seeds, insects and other small edibles, including special fungi that live around tree roots and that are critical to tree survival. Chipmunks help to spread fungi within a forest, just as they help spread seeds.
Burrows and Foods
Active by day, chipmunks shelter at night in burrows they may dig as much as 12 feet long but generally only about 3 feet deep. At the end of the burrow lies a sleeping chamber furnished with soft plant material. Some burrows include side tunnels and secondary dens. Although chipmunks tend to fight off other chipmunks that show up in the immediate area around their burrow openings, they share feeding areas with a minimum of fisticuffs.
Chipmunks produce one or two litters yearly, and young are on their own within eight weeks. Mean life expectancy is 2.3 years. During summer and fall, the rodents store seeds in their sleeping dens for use as winter food. When temperatures drop, chipmunks go underground. They don’t indulge in the deep hibernation favored by woodchucks, but instead tend to wake up periodically for a snack. On warm winter days, they may even surface above ground.
Chipmunks issue alarms calls when danger looms. Distinct calls indicate terrestrial predators and aerial predators, says Lisa Aschemeier, a biologist at Ohio’s Northwest State Community College who studies the animals. She has found that chipmunks also respond to the high-pitched alarm whistles of their relative the woodchuck, sometimes seeking cover after a woodchuck warning. Woodchucks, she says, pay less attention to chipmunk alarms, presumably because, at up to 12 pounds, they are so much bigger and need not fear as many predators as do chipmunks.
Woodchucks may not show much interest in chipmunk communications, but some bird species do. Chipmunks nosh on eggs and nestlings up to three days old when the opportunity arises. Particularly vulnerable to chipmunk attacks are veeries, a type of thrush that nests in shrubs up to 3 feet off the ground, and ovenbirds, which nest only on the ground. When these birds hear chipmunk calls, they sense danger. Kenneth Schmidt, a biologist at Texas Tech University who studies eastern chipmunks, says that veeries sometimes adjust the height of their nests in response to chipmunk calls. Both veeries and ovenbirds may shift their territories to avoid nesting within chipmunk range.
Fending Off Chipmunks
Like veeries, you, too, may want to take precautions against these cute little burrowers, especially if they have been snacking on your carefully planted bulbs. They can be discouraged without being killed, and here are some ways to do so:
- Spray shrubs, other plants and the ground around bulbs with repellent, such as the anti-deer and anti-squirrel spray sold at garden shops. The spray will need frequent refreshment, so this approach could prove costly and time consuming, depending on the size of your garden.
- Cover flower beds with quarter-inch wire mesh or hardware cloth, allowing the material to extend a foot beyond the flower bed on all sides. Cover the material with dirt if you want to hide it. When bulbs emerge, remove the mesh or cloth.
- When planting bulbs in a bed, dig out the soil, line the bed with wire mesh or hardware cloth, refill with the soil, and add bulbs.
- Keeping a gap between your garden beds and any surrounding woods will help limit chipmunk activity, because these woodland creatures prefer to avoid crossing open ground. Isolating your plantings from brush and wood piles also should help.
Adapted in part from “The Key to Chipmunk Chatter,” National Wildlife magazine, April/May 2012
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