Above the White Oak Pavilion at the arboretum, the ground is covered with freshly dug soil. This is the industrious work of a pocket gopher.
Pocket gophers are fossorial rodents named for their fur-lined, external cheek pouches. A fossorial animal is one adapted to digging and lives primarily, but not solely, underground. They have prominent, yellow incisors that are always exposed. They have small eyes, ears, and noses which probably leaves them vulnerable to predators when they are at the surface. I often see them pausing at the entrance of the hole, cautiously investigating their surroundings. They don’t leave their burrows open for very long, so you will usually see them plugged with a mound of dirt.
They prefer moist soil that is easy to excavate but can also be found in rocky landscapes. The dirt excavated by pocket gophers behind the White Oak Pavilion is littered with rounded stones, revealing that a stream once flowed through there. They have large, curved front claws for digging, and their protruding incisors probably come in handy when penetrating the dry, hard soil during the summer.
They dig extensive tunnels and the dirt typically gets deposited out in fan-shaped mounds. As they shovel the dirt to the surface, they will launch the soil away with a burst of energy.
Pocket gophers are herbivores. They forage on roots, tubers, and surface vegetation which they collect in their cheek pouches. When walking along the trail, I often see vegetation moving and then slowly disappearing as it is pulled underground.
The species we have at the arboretum is the camas pocket gopher (Thomomys bulbivorus) which is endemic to the Willamette Valley. Its distinguishing characteristic is a white patch surrounding its bottom two incisors.
Nature is an inexhaustible source of wonder. Hope to see you out there.
Resources
Burt, William Henry, and Richard Philip Grossenheider. A Field Guide to the Mammals: Field Marks of All North American Species Found North of Mexico. 3d ed, Houghton Mifflin, 1976.
“Pocket Gophers.” National Wildlife Federation, https://www.nwf.org/Home/Educational-Resources/Wildlife-Guide/Mammals/Pocket-Gophers. Accessed 28 Sept. 2022.
