People who live in the country tend to view “gophers” in much the same way city people view rats. Suffice it to say, neither animal is particularly popular.
Much of the time, when farmers, gardeners, or groundskeepers are complaining about “gophers”, the animal in question is actually a ground squirrel – and around here it’s usually a thirteen-lined ground squirrel. Although they are beautiful little animals, thirteen-lined ground squirrels have run afowl of humans because their preferred natural habitat of short-cropped grassland is very similar to that found in many yards, baseball diamonds, gardens, and crop fields. When ground squirrels move into those human-built habitats, their burrowing and feeding behavior tends to get them in trouble.
Thirteen-lined ground squirrels are very attractive animals – unless they’re eating your garden plants or digging holes in your landscaping. There are actually two ground squirrels in this photo – can you find the second one? Click on the photo to see a larger and sharper version of it.
Thirteen-lined ground squirrels (Ictidomys tridecemlineatus – formerly Spermophilus tridecemlineatus) are found throughout much of central North America. They are 5-7 inches in length, not counting their 4-6 inch tail. Their name comes from the combination of light and dark stripes that run lengthwise along their body. The lines of spots within the darker stripes are particularly striking.
Thirteen-liners have a high-pitched call – among others – that sounds much like a bird. In fact, it took me several years to figure that out. I know my grassland bird calls very well, but couldn’t for the life of me figure out what bird species kept calling but never flushing as I moved in to investigate. I finally realized it wasn’t a bird at all, which made me feel both embarrassed for being so badly wrong and satisfied that I wasn’t woefully ignorant of some common bird call.
There are several kinds of burrows made by thirteen-lined ground squirrels, each with its own purpose. Nesting burrows can be 15-20 feet long, with multiple entrances. Hiding burrows are usually scattered around nearby to provide a quick escape, but those burrows are typically very short and have only one entrance. During the winter, the ground squirrels hibernate in burrows that extend below the frost line and the entrance is plugged up until the ground thaws enough in the spring that the hungry inhabitant can burrow back out again. In all cases, thirteen-lined ground squirrels disguise the entrances of their burrows by scattering the excavated soil away from the hole itself.
Ground squirrels are themselves well camouflaged, and help disguise their burrows as well, by spreading soil out away from entrances.
Thirteen-lined ground squirrels eat seeds throughout the year, but favor them most in the fall as they prepare for hibernation. During the spring and summer, they consume green leaves, fruits, and flowers from many plants, but are also fairly significant predators, feeding on worms and insects (especially caterpillars, beetle larvae, and grasshoppers) as well as small vertebrates. In fact, grassland bird studies have shown thirteen-lined ground squirrels to be a very significant predator of both eggs and young birds in some prairie landscapes.
In my part of the world (east-central Nebraska), there are two species of ground squirrels, which are differentiated by both habitat preference and coloration. While thirteen-lined ground squirrels have distinctive striping and prefer to live in very short vegetation, Franklin’s ground squirrels are found in tall grass and are unstriped. Franklin’s ground squirrels are rarely seen, but we spot enough of them in our Platte River Prairies to assume they must be fairly common here. I’d like to know much more about their habits and needs because they are a species of conservation concern – especially in more eastern tallgrass prairie regions.
While Franklin’s ground squirrels are fairly uncommon in many places and difficult to find when they do occur, thirteen-lined ground squirrels are very common and abundant – much to the chagrin of those people who find themselves at odds with them. Thirteen-liners enjoy the more intensively grazed portions of our prairies, and seem able to find new patches of grazed prairie as we change the location of that habitat type through time. I’ve often wondered whether an individual ground squirrel actually relocates each year to keep up with those shifting patches of short-cropped prairie, or if populations just increase (and/or become more visible!) where our grazing is most intensive each year.
Ground squirrels are important prey for many of the larger predators in our prairies, including hawks, coyotes, snakes, and badgers. In fact, their popularity as badger food can compound the hassles associated with having thirteen-lined ground squirrels living in cultivated or landscaped places. In our own prairie seed nursery, ground squirrels enjoy living and running around in the plots and mowed trails between them – and we can (mostly) live with whatever damage they cause. However, the giant holes created by badgers digging ground squirrels out of their little burrows are a lot harder to ignore.
Darn gophers…
The Prairie Ecologist 