Mighty Movement Underground
- 8 hours ago
- 3 min read
By Amy Porter, Director of Conservation
Published in Salish Magazine & Wolf Tracks vol. 40, no. 3
Spring & Fall 2023
On Wolf Haven’s Patrick Vance Dunn Memorial Prairie, there is an underground movement that largely goes unnoticed – bioturbation (the movement of soil) by Mazama pocket gophers excavating their homes. Mazama pocket gophers are tiny forces of nature, moving 3-7 tons of soil per acre every year as they build and maintain a network of tunnels with separate chambers for storing food, nesting, and depositing excrement.
Pocket gophers are considered “ecosystem engineers” because their movement of soil alters the soil’s structure and chemistry, which in turn affects plant community composition and dynamics. As organic surface matter is buried by mounds, it mixes into the subsoil with decomposing food caches and excrement, creating an infusion of nutrients for plants. On Salish prairies, Mazama pocket gophers play an important role in maintaining plant species richness and diversity.
Amphibians, reptiles, small mammals, and invertebrates all benefit by sharing the landscape with pocket gophers. They use unoccupied burrows as refuge from predators and/or retreat from the elements. Coyotes, foxes, bobcats, weasels, snakes, and raptors also benefit from pocket gophers as a food source.
The Mazama pocket gopher is only found in western Washington, western Oregon, and northern California. Their distribution and abundance in the Salish region correlates with areas that have well-drained glacial outwash soils (deposits of sand and gravel carried by melting glacial ice) and herbaceous vegetation, most of which were historically prairies. Sadly, much of this habitat has been degraded, fragmented, or lost to forest succession, agriculture, and development.
Mazama pocket gophers are not restricted to prairie habitat, but soil conditions affect where they can live. Rocky soils can decrease burrowing efficiency, while soils that are high in clay have low permeability and often become waterlogged, resulting in the periodic flooding of burrows.
Along with habitat restoration efforts, translocation (moving animals from one site to another) has been another component of Mazama pocket gopher conservation. From 2005-2008, 193 pocket gophers were translocated to Wolf Haven’s prairie from sites slated for development. Our 2015 mound survey estimated the population had grown to 600 individuals.
Pocket gophers are adapted to a subterranean life, with strong claws on their front feet and prominent incisors to dig through soil and cut roots. They can close their mouth behind their incisors, loosening soil with their teeth without swallowing dirt. External, fur-lined cheek pouches enable them to transport plant material gathered underground. Narrow hips, short limbs, and loose skin facilitate their movement through tunnels, including turning around in tight spaces. They have tiny eyes, but sensitive whiskers and a sparsely haired tail provide the sensory awareness necessary to guide them through darkness.
While pocket gophers are rarely seen above ground, signatures of their movement are scattered around our prairie. Their mounds are microsites of soil disturbance that can be confused with mole mounds. The difference is that pocket gophers push soil up from inclined lateral tunnels, creating fan-shaped mounds, whereas moles push soil up from vertical shafts, creating dome-shaped mounds. Pocket gopher mounds also tend to be irregularly shaped compared to more uniformly rounded mole mounds.
Life moving through the underground often escapes our attention. If you are patient and observant, you may catch a glimpse of something extraordinary. Perhaps you catch a wiggle in the vegetation, or maybe you are lucky enough to witness a pocket gopher briefly emerge on the surface, cram its cheek pouches with food, then vanish. But if you miss them, their mounds remind us there is a mighty movement happening underground, contributing to healthy ecosystems.
*This is an adaptation from an article recently published in Salish Magazine. For the full article, please visit: salishmagazine.org/underground-movement
