Issue 2, May 8, 2017

Chipmunk vs. Ground Squirrel

Two little furry creatures run around yards, potentially wreaking havoc on plants and the soil:  the Eastern chipmunk and the thirteen-lined ground squirrel.  They can be easily confused and are often treated as one.

The Eastern chipmunk is a reddish brown to tan type of ground rodent with several alternating dark and light stripes (typically around 5) on its back and sides and sides of its head, with cream-colored fur on the stomach.  Ears are rounded and often erect like a cat.  The tail is somewhat furry and fat, but not bushy and usually held erect as it scurries about the yard.  The chipmunk is about five to six inches long.  

Eastern chipmunk.

The chipmunk has great cheek pouches, which they can stuff with food.  You're more likely to find the Eastern Chipmunk on the edge of wooded areas or in yards with lots of trees, shrubs and perennials.  You can see them scurry partway up a tree. They are close relatives of tree squirrels. Burrows under sidewalks and driveways can cause their collapse.

There can be two litters per year, one in the spring and one in late summer.  The Eastern chipmunk does not hibernate.

The 13-lined ground squirrel has just that:  13 stripes on the body, also running to the head but not on the cheeks like the chipmunk.  The lighter stripes are yellowish-white while the dark ones are reddish brown.  There are often spots on the stripes.  Their ears are quite small.  They have short bushy tails which they carry horizontally instead of upright.

13-lined ground squirrel.

Ground squirrels prefer more grassy areas such as pastures, golf courses, and cemeteries.  There is only one generation per year, with the ground squirrels hibernating during the winter.

Both creatures are active during the day, and tend to be solitary, though you may have several in the landscape.

Food includes nuts, seeds, berries and many insects such as crickets, beetles and grasshoppers.  Both the Eastern chipmunk and the 13-lined ground squirrel will tunnel under trees, shrubs, patios, sidewalks and flowerbeds, usually creating multiple openings, though the chipmunk usually has one main opening.  Tunnels can be 20-30 feet long.  The tunneling tends to cause more problems than the feeding.

No chemical products are labeled for control.  Live trapping may be possible, but likely will not result in a "chipmunk/ground squirrel" free yard.  Rat snap traps can be used, but may result in other creatures being caught.  Fumigants may work but shouldn't be used under or around homes.  Read and follow the directions on the label.

Research has shown that reductions in these mammals opens up suitable habitat areas, resulting in adjoining populations increasing reproduction to fill the void. Similarly, populations will rise to the carrying capacity and then reproduction will reduce to replacement rather than increase. In other words, if nothing is done, the number of these rodents will remain somewhat constant, but if individuals are removed, their numbers will rebound quickly.

Make sure to avoid feeding the chipmunks or ground squirrels.  Clean up spilled birdseed. These and other actions to reduce food sources will lower the carrying capacity and numbers will naturally decrease. (David Robson)

David Robson

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