The Dry Garden: Détente with the gopher
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Plant ecologist Paula Schiffman came to praise gophers when she packed a lecture last spring hosted by the Los Angeles chapter of the California Native Plant Society. It was awkward for the Cal State Northridge professor, given that most of the audience filling a cold, no-frills Santa Monica meeting room had come to learn how to kill the animals.
The atmosphere only got colder as Schiffman’s live-and-let-live message began to sink in: Gophers were here before us, they are integral to our local ecology, and one of the most common ways that we kill them also can accidentally poison a whole host of other animals.
Anyone who gardens with gophers can imagine the crowd’s aloof response. But even as fall planting season is in full swing, and we find seedlings and young plants either dug up and dragged under, it merits hearing Schiffman out.
Thomomys bottae, as the burrowing animal is officially known, owes its genus name to “the Greek terms thomos and mys, meaning ‘a heap’ and ‘a mouse,’ respectively,” according to a treatment from the American Society of Mammalogists. The species name, evidently, “honors Dr. Paolo Emilio Botta (1802–1870), a collector for the Museum of Natural History of Paris and one of the first naturalists to collect specimens in California.” To Schiffman, who studies grassland ecology, gophers amount to nature’s own engineers. Their tunneling talents were so evident when early explorers beheld California that the 16th century British explorer Sir Francis Drake noted in his diary, “We found a whole country to be a warren of a strange kind of conies.”
Of the ‘conies,’ or burrowing animals noted by Drake -- gophers, voles, moles, kangaroo rats and ground squirrels -- it is the pocket gopher that drives modern gardeners nuts. Unlike insect-eating moles and seed-eating voles, gophers appreciate tender roots and fresh green leaves. One 1939 study quoted by the mammalogists society even claimed to have detected “the rasping sound of the gophers’ teeth shearing through the plant fibers” from 20 to 30 feet away.
Hmmm. What good hearing they had back in the day.
The good news about these supposedly rasping gophers, Schiffman said, is that they are shy. They rarely venture beyond the immediate mouth of a burrow, so if you create a raised bed, you’re unlikely to have gophers jumping fences. Another heartening piece of gopher trivia was the news that their populations level out. One report estimates maximum capacity at 30 an acre. Whatever it is, if you have been living with gophers for a while, your gopher hotel is probably full. They are territorial. You won’t have more.
A signature of gophers, as opposed to other tunnelers, are nuisance mounds of earth kicked up during excavation. Reading about gophers, the surprise is that they don’t kick up more earth. Estimates reported by Schiffman put the warrens anywhere from 6 inches to roughly a foot and a half deep and as long as 16 feet, though this burrow system is by no means in a straight line. Gophers, it seems, prefer paths of least resistance. A trap-them-kill-them UC Davis pest management sheet gives the burrow diameter at 6 inches and says nests can be as deep as 6 feet.
One upside of living with gophers (surprisingly, there are many) is that their tunnels create habitat for some of the garden’s most beneficial gleaners, including lizards, toads and even burrowing owls. Another benefit is tillage. A gardener with gophers is unlikely to suffer from soil compaction. Schiffman cited estimates that gophers will turn over soil around their burrows roughly every three to 15 years.
This leads to a personal observation. As someone who gardens on a remnant of an old Altadena farm and who walks as often as possible at Hahamongna Watershed Park in Pasadena, it’s interesting to note that in the gopher-rich foothills, the large citrus trees at home and the old oaks of Hahamongna seem not only to tolerate active burrows around their trunks, but also benefit from greater water infiltration.
It’s getting trees established that may be the challenge, Schiffman interjected during a recent follow-up interview. Of traditional methods for keeping gophers at bay, she doubted that the humming of a whirlygig -- a common gardener solution -- will do much.
“I can’t imagine the vibration would travel very far through dense soil,” she said. “But if it did, would they care?”
Adopting a small dog strikes her as a possibly effective option, though the dog may do more damage than the gopher. But she is strongly against poisoning.
The hardest thing to hear during her lecture wasn’t about lost rose bushes or ankles sprained in gopher holes, but the result of a National Park Service study that found the majority of bobcats tested in the Santa Monica Mountains had consumed rodenticide. The toll became more grim when talk turned to common gopher poisons’ effects on mountain lions, coyotes and owls. As a pet owner, I couldn’t help thinking about my dogs. A strong correlation between mange and gopher poison was so unnerving, it had Schiffman’s audience vicariously itching.
Trapping has been one reaction, but once a gopher was in a cage, who among us would know what to do with a disgruntled rodent? By the end of Schiffman’s lecture, I was convinced that the only safe way to defend vegetables from gophers was to out-engineer nature’s own tunnelers. Line vegetable plots with brick or wood or stone to two feet deep. Then line this barrier with wire mesh.
So far, the strategy has worked. Generous inter-planting of poppies and sunflowers also seems to have kept the bulging cheek sacks of gophers full of seeds instead of roots and leaves. Of dozens of stone fruit trees, roses, native fuchsias, lilacs and sages put in my garden last autumn, I’ve lost two small sages and one zauschneria cutting. Not bad for a third of an acre with at least a dozen gophers. The rest of the plantings benefited from deep percolation of rain and irrigation.
With that, fellow gardeners, let us all depart the chill room that we enter, either literally or metaphorically, when we think about what we would like to do to gophers.
-- Emily Green
Paula Schiffman will lecture on gophers at 7 p.m. Nov. 16 at the Solvang library, 1745 Mission Drive. The talk is sponsored by the Santa Ynez Valley Natural History Society.
Green’s column on sustainable gardening appears here on Fridays. For an easy way to follow future installments, join our Facebook page dedicated to gardening in the West.