Pocket gophers are unlikely to be 4-H members, but the rodents may be farming roots in the open air of their moist, nutrient-rich tunnels.
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The gophers eat mostly roots found in the tunnels excavated by the rodents. However, two researchers report in the July 11 issue of Current Biology that the local terrain does not always provide enough roots to sustain gophers. To make up for the shortfall, gophers engage in simple agriculture, creating conditions that encourage more root growth, according to ecologist Jack Putz of the University of Florida in Gainesville and his former zoology undergraduate student Veronica Selden.
However, some scientists believe that referring to rodents' activity as farming is a stretch. Gophers aren't actively working the soil, according to these researchers, but they are inadvertently altering the environment as they eat and poop their way around, as all animals do.
Tunnel digging requires a lot of energy — up to 3,400 times as much as gophers walking along the surface. Selden and Putz began investigating the tunnels of southeastern pocket gophers (Geomys pinetis) in an area being restored to longleaf pine savanna in Florida that Putz partially owns in 2021 to see where the critters were getting all this energy.
The researchers collected root samples from soil near 12 gopher tunnels and calculated how much root mass a gopher would encounter as it excavated a meter of the tunnel. The researchers then calculated how much energy those roots would provide.
"We were able to compare energy cost versus gain and discovered that there is an average deficit, with roughly half of the cost of digging unaccounted for," Selden says.
Selden and Putz discovered gopher feces spread throughout the interior of some tunnels, as well as signs of small bites taken out of roots and soil churning.
The researchers conclude that gophers promote root growth by spreading their waste as fertilizer, aerating the soil, and repeatedly nibbling on roots to encourage new sprouting.
"All of these activities promote root growth, and once the roots reach the tunnels, the gophers crop the roots," Selden explains. According to her and Putz, this is a primitive form of farming. Putz believes that if this is true, gophers will be the first nonhuman mammals to be recognized as farmers. Other organisms, such as insects, farm food and have done so for much longer than humans.
However, the study has its detractors. "I don't think you can call it farming in the human sense." "All herbivores eat plants, and everyone poops," says J.T. Pynne, a southeastern pocket gopher researcher at the Georgia Wildlife Federation in Covington. So the root nibbling and tunnel feces may not be agricultural signs, but rather gophers doing what all animals do.
Ulrich Mueller, an evolutionary biologist, concurs. "If we accept the flimsy evidence presented in the Selden article as evidence for farming... then most mammals and most birds are farmers because they all unintentionally have some beneficial effects on some plants that these mammals or birds also feed on," he says.
Not only that, but according to Mueller of the University of Texas at Austin, the study is also dangerous. He claims that the public will see through "the shallowness of the data" and conclude that science is "just a bunch of storytelling," eroding public trust in science.
Selden, for one, understands that because gophers do not plant their crops, not everyone is comfortable referring to them as farmers. Nonetheless, she contends that "what qualifies gophers as farmers and distinguishes them from, say, cattle, which incidentally fertilize the grass they eat with their wastes, is that gophers cultivate and maintain this ideal environment for roots to grow into."
Putz says he hopes their research makes people more compassionate toward rodents. "If you search the term 'pocket gopher,' you'll find more ways to kill them than you can count."