Dirk Stevenson (Altamaha Environmental Consulting)
Keep reading to learn more about the lives of another kind of burrower, the southeastern pocket gopher, and some of its unique burrow commensals.
Walking a primitive road near Rainbow Springs State Park in Dunnellon, Florida, I glanced into a turkey oak sandhill to witness something cartoonish. New green plants, over two feet tall, were being pulled and yanked repeatedly, disappearing, a few inches at a time, underground. What in the world? Later the same day, I met a grizzled old-timer who owned the adjacent land. He said he often saw a big blue indigo snake on walks to his mailbox. He knew indigos were the archnemesis of rattlers, which he called bellboys.
We spoke for some time. When I told him I studied amphibians — “you know, frogs and salamanders” — he guffawed, tongue-shifted his chaw, and pointed to a dozen piles of yellow sand under the nearby pines, “Salamanders, they’re everywhere!” Salamander, a corruption of “sandy-mounder,” is a folk term for our intriguing southeastern pocket gopher, Geomys pinetis. (Later, I deduced who made the mounds and solved the puzzle — the disappearing plants was the work of a pocket gopher.)
At 10 to 12 inches long, pocket gophers are sizeable rodents. Tiny eyes and ears accompanied by large incisors lend them an endearing countenance. The lips of pocket gophers close behind the protruding teeth so that gophers can gnaw about underground to their hearts’ content without swallowing a mouthful of sand. Their long, strong digging claws look like they belong on a sloth. Those whiskers and that naked, sensitive tail allow this earth rodent to ambulate backwards in the tight quarters of its tunnel.
Pocket gopher expert Dr. Steven Castleberry, professor of Wildlife Ecology and Management at the University of Georgia, told me of another remarkable characteristic. “Pocket gophers have external, fur-lined cheek pouches, with openings to these “pockets” on the outside, not the inside, of the mouth. They pack the cheek pouches full of plant material to transport back to a food storage chamber in their burrow.” Yes, the burrows of pocket gophers are compartmentalized, with specific chambers for food storage, grass-lined lodges for nesting, and, unlike the slovenly namesake of this newsletter, “dung chambers” for bathroom events. These brown-gray, solitary burrowers feed mostly on roots and tubers of understory vegetation and spend almost all their lives underground.
The main runs of pocket gopher burrows are about a half-foot to three-feet deep and parallel to the ground surface. Burrow systems can exceed 500 feet in length. Mounds, formed when the resident gopher pushes excavated sand to the surface and big enough to appear in aerial photos, mark the pocket gopher’s subterranean meanderings.
Typically, there is one pocket gopher per burrow system, and individuals fiercely defend their tunnels against intruding gophers. Some researchers have described gophers as “homely, belligerent sausages”; although I can’t speak to their temperament, I acknowledge that they possess a physique that qualifies as frankfurter-esque. The burrow systems of females branch and wander while burrows of males are sometimes linear, a product of mate-searching (i.e., enhancing Sir Geomys’s chances of locating Lady Geomys underground).
Pocket gopher populations have been extirpated throughout much of the species’ Coastal Plain range, which includes southern Georgia, the northern half of Florida, and southern Alabama. Recent surveys by Castleberry and colleagues in Georgia located pocket gophers at only 25 percent of historic sites, and similar declines have occurred in Florida and Alabama. According to Castleberry, “Generally, the declines are related to changes in land use and altered fire regimes. There are similarities between the pocket gopher and gopher tortoise as both are adapted to open-canopy pine habitat with frequent fire.”
From Gopherus 101, you may remember that the domiciles of gopher tortoises are cave-like ecosystems. The deep, dry burrows exist on the landscape for many decades, and their dark confines offer stable, humid microclimates and, seasonally, an abundance of fresh tortoise dung that drives a food web comprised of “obligate commensal” flies, moths, and beetles.
Similarly, pocket gopher burrows are home to invertebrate species found nowhere else on the globe. The cryptic diversity of pocket gopher burrows was there all the time, simply waiting for talented entomologists to come find and describe it. In their inspirational 2001 paper, “Insect Surveys in the Southeast: Investigating a Relictual Entomofauna,” coleopterists Paul E. Skelley and Peter W. Kovarik review their exciting discoveries sampling pocket gopher tunnels. When they initiated surveys around 1990, only a single specimen of an unusual clown beetle (Onthophilus giganteus, Histeridae) was known to science. When they visited the type locality — a sandy field near Archer, Alachua County, Florida —they noted the presence of Geomys mounds. One of their colleagues mentioned that Onthophilus spp. was often associated with burrowing rodents. Subsequent pitfall trapping of pocket gopher burrows on-site soon produced 50 specimens of O. giganteus and several undescribed aphodine scarab beetles.
Skelley and Kovarik went on to survey many dozens of pocket gopher populations in Georgia, Alabama, and Florida, cataloguing a total of 15 new scarab and hister beetle species along the way, all of which are obligate burrow commensals and dung specialists. They also encountered the strange commensal Typhloceuthophilus floridanus, a long-legged, blind, pallid cave cricket. Some of the pocket gopher nest and food chambers disclosed by their excavations were six feet deep.
I learned that the strange pocket gopher burrow insects new to science included a small dung beetle called Aphodius baileyi (described by Skelley and colleague Robert Gordon). I couldn’t help but wonder, could this little dung-sucker be named for the herpetologist Mark Bailey? I recently asked the Alabama biologist if he did, in fact, have a pocket gopher beetle named for him. “All the cool kids do. I was perusing a list of imperiled species a couple of years ago and Bailey's Pocket Gopher Dung Beetle caught my eye. Somehow seeing the common name written out like that made it all the more real.”
Animals with backbones associate with pocket gophers, too. Herpetologists stir the mounds of pocket gophers in search of mole skinks — gorgeous lizards with a salmon-colored tails that love to bask in the warm sand. Once my stirrings turned up a southern hognose snake. Another herp common to Geomys country is the Florida pine snake (Pituophis melanoleucus mugitus). Equipped with reinforced bones in the skull and a heavy-duty rostral scale on the end of their pointy snouts, these five-foot long constrictors are specialized for preying on pocket gophers. Pocket gophers tightly plug, with sand, connections between their burrow runs and surface mounds to discourage entry by predators (and conspecifics). But pine snakes are adept at busting in.
One spring, while conducting an amphibian/reptile inventory on the north side of Lake Panasoffkee, I scaled a pretty sand ridge above one of those handsome central Florida depression marshes, green with maidencane, to discover my first-ever pine snake, its rear half sticking out of a Geomys mound. It was a big one. Quivering, I removed it from the sand and looked it in the eye. You will long remember the first time a pissed off Pituophis parts its lips and hisses in your face, the feel of its tail drumming against your thigh.
A longleaf pine upland replete with pocket gopher mounds and the aprons of gopher tortoise burrows is reassuring. We know life is abundant and diverse, even if invisible. However, you will seldom, if ever, see an actual southeastern pocket gopher in the wild. They are that fossorial. Just for fun, we can contemplate — as did Franz Kafka in his unfinished short story The Burrow — what occupies the mind of an animal like a pocket gopher during those countless hours underground, in its impressively constructed and wonderfully biodiverse home: The most beautiful thing about my burrow is the stillness. Of course, that is deceptive. At any moment it may be shattered and then all will be over. For the time being, however, the silence is with me.