Wild Neighbors: The Subterraneans—Life Among the Pocket Gophers

By Joe Eaton
Thursday July 31, 2008 - 10:25:00 AM

Years ago, probably while watching a bird or watching for a bird, I saw a dandelion move. Not a breeze-driven sway, but a sort of convulsive shudder. And then it slowly retracted into the ground. It was like watching one of those nature-documentary time-lapse sequences in reverse. Then I realized a pocket gopher must be at work. 

The presence of a gopher is usually detected by the earth mounds from its excavations (not to be confused with mole hills) or the damage it does to plants. But sometimes you can see the actual critter as it shoves dirt out of its tunnel system. It’s a chunky, virtually neckless, beady-eyed rodent with alarming yellow incisor teeth. Those teeth are used like a bulldozer blade to push loose soil. 

You seldom see more than the gopher’s head and shoulders; it keeps its lower body anchored in the burrow in case a fast retreat is needed. The effect is rather hand-puppet-like. Usually retiring, gophers may engage in vigorous territorial defense; I once saw one rear back and squeak defiantly at a German shepherd. 

The teeth are part of the gopher’s suite of adaptations to life underground. Both the upper and lower sets project through the rodent’s lips and are exposed even when it closes its mouth, so it can dig or bite into roots without getting a mouthful of dirt. Its forelimbs, heavily muscled and equipped with long claws, are also efficient digging tools. Loose skin allows it to turn around in the confined space of its burrow, where it can move backward or forward with equal ease. A gopher’s tunnel system can extend over 100 feet and includes a grass-lined bedroom and several latrines. 

Unlike the colonial prairie dog, gophers are about as social as tigers, tolerating each other’s company only during the mating season. Females may have several litters each year. When they are two months old the young leave their mother’s burrow, traveling above ground at night to find suitable digs of their own. But the housing market can be tight; an acre of good habitat may contain a hundred gophers, each defending its turf fiercely.  

You may have wondered where a pocket gopher keeps its pockets. They’re fur-lined external pouches in its cheeks into which it stuffs food to be transported to storerooms in its burrow complex. (More typical rodents, like chipmunks, have internal cheek pouches). The pockets can be turned inside out for cleaning; a special muscle snaps them back into place, like a cheap change purse. 

Gophers browse on leaves and grasses around their tunnel openings and harvest roots and tubers underground. They’ll eat just about any kind of plant, given the opportunity, and our farms and gardens are gopher buffets. They’re fond of alfalfa and of root crops like carrots, potatoes and sugar beets. Some nurseries sell a plant called gopher purge that’s said to repel them, but I’m told its effect is mostly mythical. 

The gopher lineage goes back at least four million years in the fossil record. (Some early models had horns, an unusual departure for a rodent.) The lice that live in their fur have evolved along with them. Most gopher species have their unique species of louse, the parasite’s mouthparts fitting the host’s hair like a lock and key. 

Four million years represents a lot of digging time, and a significant environmental impact. Although we tend to think of it as a uniquely human trait, Homo sapiens is not the only species that alters its environment in a major way: think of beavers’ engineering feats, or the foraging activities of creatures as disparate as leafcutter ants and African elephants. The pocket gopher has a definite place on that list. 

Back in the 1920s Joseph Grinnell, a pioneer student of western mammals and birds, wrote an article titled “The Burrowing Rodents of California as Agents in Soil Formation.” Noting Darwin’s study of how English earthworms circulated topsoil, he claimed a similar role for North American pocket gophers. He estimated the amount of earth moved by gophers in Yosemite National Park during the winter as 3.6 tons per square mile, and extrapolated that to 8000 tons each year.  

Grinnell didn’t minimize the threat gophers posed to crops. But, long before “ecology” was in vogue, he saw the rodents as a vital part of natural systems: “We do not agree with the policy of wholesale extermination advocated by some persons for all areas alike … We hold that our native plant life, on hill and mountainside, in canyon and mountain meadow, would soon begin to depreciate, were the gopher population completely destroyed … On wild land the burrowing rodent is one of the necessary factors in the system of natural well-being.”  

I suspect that philosophical stance would be difficult to maintain if your own carrots were going missing.