In All Seriousness, Pocket Gophers are a Keystone Species

Portrait of a pocket gopher (Thomomys bottae), photo by Steven Hammerich.

By Anne Carol Mitchell, certified California Naturalist and Climate Steward

When I told my friend that I was writing an article about pocket gophers as a keystone species, she literally burst out laughing. The term keystone species brings to mind iconic examples, such as gray wolves that were hunted, trapped, and poisoned out of Yellowstone National Park in the 1920s with disastrous repercussions. The demise of gray wolves led to the decimation of aspen and willow forests by elk, who had been kept in check by the wolves. Without the presence of a keystone species in an ecosystem, like a proverbial keystone in an arch, things fall apart. How could the maligned pocket gopher possibly be in the same league as a gray wolf? Keystone species, as I’m learning, can take many forms besides a legendary predator. They can be a humble plant, an unassuming fungi, inconspicuous bacteria, or even a destructive pocket gopher.   

My friend, like me, is a dedicated food gardener with years of experience and a fierce attachment to carefully tended plots. That is why my friend thought I was telling a joke. Gophers are rapscallions in the gardening world. This perspective made it difficult for my friend, and me before working on this article, to fathom that gophers have another function besides chomping a broccoli plant in the time it takes to say “Thomomys bottae,” aka pocket gopher. 

Despite being continually aggravated by these underground ninjas in my garden, I respect them. Early on in growing food, I learned from farming friends how to put a stop to their munching on my plants through the proper use of cinch traps, designed to instantaneously and humanely kill them. I don’t revel in killing gophers and have taken this responsibility to heart in only going after them when they go after plants, not using products that are harmful to other wildlife, and educating myself in the correct use of traps. 

The silver lining in this unsavory business has been an education in their acute senses and sharp wits. As Brock Dolman shared in his DIY primer for setting traps called the Gopher Getting Guide, for what the gopher “has evolved to do, there is no more intelligent life form in the known universe!” Gophers have keen hearing and sensitive noses. I learned that trap-setting must be a quiet activity, beginning with ceremoniously crushing a kale leaf and thoroughly rubbing it on the traps, as well as my hands and arms, to mask my scent. Gophers are smart. When they sensed my traps, I returned to find my handiwork buried in copious layers of soil and, on occasion, the traps were buried forever. 

But they’re not just canny creatures. A recent scientific discovery found that southeastern pocket gophers are biofluorescent, meaning they glow under ultraviolet light. It’s unclear why exactly this is. I also learned that gophers have actual pockets, which I find ingenious. Their fur-lined cheek pouches are used for foraging, and carrying bits of food back to their caches. Perhaps the most inspiring information for me about gophers is that they are tough and hard-working ecosystem engineers in the grasslands. 

When I told Valerie Eviner, UC Davis professor of Ecosystem Management and Restoration who works in grassland research, about the article I was writing she had a different reaction than my friend, “What a fun article!” she emailed back to me. She went on to share with me research that instantaneously illuminated my one-sided perspective on gophers. The destructive behavior of gophers of tunneling in order to forage – behavior that brings gardeners to tears – is “an important tool in grasslands,” according to Eviner. In fact, Eviner didn’t use the word “destruction” in referring to gophers. She used the word “disruption.” Disruption is “what keeps diversity going,” Eviner said. 

In the context of a grassland, disruption is the gopher’s keystone superpower. The churning of soil through burrowing activity moves nutrients vertically through the soil strata, or layers, changing the conditions of the soil, and creating a patchiness of bare mounds across the landscape. These mounds contain different arrays of soil as compared to surrounding soil, and they contain another important ingredient in grasslands: seeds. In Eviner’s research looking at wildfire recovery at Pepperwood and at a similar site at the Hopland Research & Extension Center, she is finding that the mounds are repositories of buried seeds that can survive wildfire to repopulate the grassland. Eviner calls these mounds “islands of recovery.” 

And another thing about gophers that further endears them to me and illuminates their keystone status: that “patchiness” that gophers engineer across the landscape is an important feature for biodiversity. The variance of soil conditions and plant species contained within the islands of recovery, contribute to a more resilient grassland able to adapt to a changing climate. As ecosystem engineers, the gopher creates, modifies, and maintains the grassland, strengthening biodiversity and overall health and resilience in the process. 

But that’s not all that gophers do for grasslands. Gophers create critical habitat for amphibians and reptiles through the tunnels they build. Trish Tatarian, a wildlife biologist and the Conservation Chair for the Milo Baker California Native Plant Society, has extensively researched cohabitation of amphibians and underground mammals. When I emailed her about this article, her first words back to me were, “I’m so glad you’re writing about the importance of pocket gophers,” and then she went on to share some of her fascinating research on this subject.

Underground burrows of gophers serve as dry season homes for the endangered California tiger salamander (Ambystoma californiense) whose populations have dwindled along with the numerous vernal pool wetlands in the Santa Rosa Plain of Sonoma County. Because California tiger salamanders need both upland terrestrial and aquatic habitat for their life cycle, gopher burrows are much-needed abodes for them to survive underground during the extended rainless period in this climate. The California tiger salamander is also a keystone species, being both predator and prey in the food web. I can’t help but imagine a cute, below-ground scene with these two keystone species, an amphibian and a mammal, chilling in the dark during a long hot summer day. Below is a video showing two gopher snakes hunting in a gopher burrow. 

As my perspective continues to shift about the underrated gopher, it makes me wonder if other minds can be changed. I’m thinking especially about large-scale agriculture and the legendary abhorrence the industry has towards gophers. In this sector, gophers reap annual damages somewhere between $28M and $91M, depending on the year and region in California, damaging crops, reducing forage on grazing lands, mangling irrigation, and contributing to soil erosion. To control gopher populations, fumigants and toxic baits are commonly used. Toxic baits have secondary kill effects on raptors, foxes, coyotes, and mountain lions. Fumigants are harmful and dangerous to humans and have negative impacts on the environment. 

What if these industries took into account that gophers are a keystone species engineering biodiversity, which is valuable to the production and longevity of the vineyard, farm field, and range? Could this lead to the introduction of more ecologically friendly practices, like planting buffer zones of crops that don’t sustain gophers, rotating crops to control gopher populations, choosing less vulnerable crop varieties, or using less irrigation to reduce the lush appeal of crops to name a few? With an effective PR campaign, could there be more information available to farmers and ranchers about the benefits of gophers and how to manage them in less malignant ways?

It’s unlikely that gophers and the agricultural industry can live an entirely peaceful existence, just as I know that if a gopher goes after the kale in my garden, I will use a cinch trap. Yet, the gopher as a vilified pest that is also a keystone species, brings into focus other and, perhaps, more far-reaching questions in an age of climate change. As the climate continues to be a rollercoaster of drought, flood, fire, and no fire, we don’t know what organisms will be critical to our stressed ecosystems. The fact that gophers help engineer and preserve biodiversity holds the promise of a more resilient grassland able to weather the changes that are so difficult to predict. 

Could underappreciated organisms, like the pocket gopher, turn out to be unexpected climate heroes? I asked Valerie Eviner this question. While she thought it a good question, she felt the gopher as a “climate hero” was taking it a bit far. However, the question is worth some musing. At this point, the agricultural industry might not shed a tear should the pocket gopher disappear from the farm, but the animals, plants, and systems that rely on gophers would be devastated by their absence on the grassland. Like a keystone holding the arch in place, a species that supports fire recovery, provides critical habitat, and promotes biodiversity is not only important but invaluable. 


Post a comment

Traducir »