Grinnies – Something to Smile About

Grinny, ground hackee, chippie, hackle, and rock squirrel. These are some of the colloquial names for the Eastern Chipmunk (Tamias striatus). The name “chipmunk” is thought to come from the Ojibwe word ajidamoo, meaning “one who descends trees headlong.” Most people think chipmunks are only found on the ground, but they are actually very good climbers and will climb trees to gather nuts.

Eastern Chipmunks are found in deciduous forests in the eastern half of United States (except for the deep South) and southern Canada. Photo by Kaldari, CC0, via Wikimedia Commons.

Chipmunks are easily seen now in the fall as they gather nuts and seeds for the winter. In a few weeks, they will retreat into their burrows and not emerge until mid-March or April, depending on temperatures and snow depth.

An Eastern Chipmunk’s burrow system is a maze of interconnecting tunnels, usually from 12 to 30 feet (4 to 10 meters) long and about 2 inches (5 centimeters) in diameter. Their tunnels are from 2 to 3 feet deep. A few deeper tunnels serve as drains to help prevent flooding. The main entrance is usually left open. There are also secondary escape routes plugged with leaves. A burrow will also have several food galleries, a chamber for waste, and a nesting area.

The Eastern Chipmunk’s stretchable cheek pouches can hold lots of seeds, which it carries to its underground storage areas. One animal was observed with 32 American Beech (Fagus grandifolia) nuts in its pouches. Another had 72 sunflower seeds. Now that’s one cheeky animal!

As you can see in this photo, Eastern Chipmunks can hold a lot nuts and seeds in their cheek pouches! This comical look may have been the inspiration for the cartoon “Alvin and the Chipmunks.” Photo by Cephas, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0&gt;, via Wikimedia Commons.

Even though you may not see them, chipmunks don’t sleep the winter away. Eastern Chipmunks are not true hibernators, but “catnappers” that undergo periodic torpor. Their deep core body temperature falls to as low as 40° F (4.4 ° C) and their heart rate slows to four beats per minute. After sleeping for a few days to two weeks, they wake up to feed and defecate. Research has shown that an Eastern Chipmunk stores 5,000 to 6,000 nuts to get through the winter! Juvenile chipmunks and those whose burrows were raided have been observed to scatter-hoard nuts by burying them in temporary caches and returning to eat them later. That’s one way nuts that aren’t eaten sprout into trees.

Most people see Eastern Chipmunks on the ground, but they are actually really good climbers and will hunt in the canopy for nuts, particularly those of American Beech (Fagus grandifolia). Photo by David Whelan, CC0, via Wikimedia Commons.

Chipmunks also feed on other seeds, fleshy fruits, leaves, worms, fungi, and occasionally bird eggs. They in turn are preyed on by hawks, coyotes, raccoons, foxes, owls, snakes, weasels, bobcats, and unfortunately domestic dogs and cats.

Although chipmunks vocalize to protect their territories from other chipmunks, they are famous for their high frequency “chip, chip” (actually ear-splitting up close). This often signals a ground predator (including us!) nearby. Years ago, I was stymied by a “cluck, cluck” sound I kept hearing in the forest. It was actually the sound a chipmunk makes when an aerial predator, such as a hawk, is nearby.

During a January thaw chipmunks can sometimes be seen at bird feeders eating sunflower seeds. They are diurnal, leaving their burrows during the day. This summer I have heard from many people wondering where all the chipmunks have gone. They are not as active during hot, windy, and rainy weather. Some stay in their burrows during much of July and August, which could be a response to scarce food and parasitism by botflies.

You might not be grinning when chipmunks dig up and eat your tulip and crocus bulbs. Plant these with one-half-inch hardware cloth over the bulbs, or in bulb cages, to discourage chipmunks. The plants will grow through the screening. You can also intersperse the bulbs with narcissus, which chipmunks don’t like.

Eastern Chipmunks are solitary creatures, except during two brief courting and mating seasons from February to April and again from June to August. Females will have one to two litters, each with three to seven young.

Although they occasionally cause damage to our plantings, chipmunks are an important part of our local forest ecosystem. They provide food for many other animals, aerate and drain soils, and spread fungal spores, which may create favorable conditions for tree seedlings.

Published by Jim Sirch

Jim Sirch is the author of Beyond Your Back Door, a weekly blog about nature in your neighborhood. He is also Education Coordinator for the Yale Peabody Museum, a UConn Master Gardener and board member of his local land trust. As a trained naturalist, he brings a deep understanding of geology, plants and wildlife and how they interact within a particular ecosystem. He holds a B.S in Forestry from West Virginia University, a B.S. from Miami University in Science Education; and an M.S. in Environmental Studies Administration from Antioch University. He is also the 2014 Sigmund Abeles Award recipient from the Connecticut Science Teachers and Supervisors Association for outstanding science teaching and professional development.

7 thoughts on “Grinnies – Something to Smile About

  1. That was fascinating about the chipmunks. I didn’t realize how extensive their tunnels are. I know they live in this area but I don’t have any in my neighborhood. I just have the black squirrels. I love the suggestion about the narcissus between the other bulbs. I hope the squirrels don’t like them either! I’m going to try that. Thanks a lot, Jim. I really enjoyed your posts.

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