Pocket gophers: busy little critters
There are fresh mounds of dirt where we walk into Frisco Rowing Center each morning. There are no tunnels, so I don’t think it is a mole, and it is not cone-shaped, which would be a vole. The best guess would be that the creature that has made its home in the Marina is a northern pocket gopher.
Pocket gophers are the most common species in mountain rangelands and forests. This 6-10 inch-long rodent is dark-colored with a whitish chin and belly. They are burrowing rodents and they have fur-lined, external cheek pouches, or pockets, which they use for carrying food and nesting materials, hence the name “pocket” gopher. These pockets on a gopher open on the outside and turn inside out for emptying and cleaning.
They spend their lives digging and tunneling in the soil with powerfully built forearms and large-clawed front paws. They are well adapted for this underground existence as they have fine, short fur that doesn’t cake in wet soils and small eyes and ears. Their highly sensitive facial whiskers assist with moving about underground in the dark. Their sparsely haired tails also serve as a sensory mechanism to help gophers run backward almost as fast as they can run forward. A gopher’s lips also are also unusually adapted for their lifestyle as they can close behind four large incisor teeth, and this keeps dirt out of their mouths when they use their teeth for digging.
Pocket gophers usually construct one to three mounds per day, although the rate varies. One gopher can bring about 2-1/4 tons of soil to the surface each year. Mound-building activity usually is greatest in spring and fall. They construct burrow systems by loosening the soil with their claws and incisors, and then use their forefeet and chest to push the soil out of the burrow. The soil is deposited in fan-shaped mounds 12 to 18 inches wide and 4 to 6 inches high. The hole, which is off to one side of the mound, usually is plugged. In irrigated areas such as lawns, flower beds and gardens, digging conditions usually are optimal year round, and mounds can appear at any time. In snowy regions, gophers create burrows in the snow, resulting in long, earthen cores on the surface when the snow melts.
Burrow systems consist of a main tunnel, generally 4 to 18 inches below the soil surface, and a number of lateral burrows extending from the main one. Lateral burrows end with a soil mound or only a soil plug at the surface. Burrows are about 2 to 3-1/2 inches in diameter, may be linear to highly branched, may contain up to 200 yards of tunnels, and may have many mounds. Their burrow system can cover an area that is 200 to 2,000 square feet. The feeding burrows usually are usually 6 to 12 inches below ground, and the nest and food storage chamber can be as deep as 6 feet. Short, sloping lateral tunnels connect the main burrow system to the surface.
Gophers don’t hibernate and are active year-round, although you might not see any fresh mounding. They also can be active at all hours of the day.
Gophers usually live alone within their burrow system, except when females are caring for their young or during breeding season. Gophers reach sexual maturity about 1 year of age and can live up to three years. Pocket gophers breed in the spring and produce one litter of one to 10 young (typically three to four) after a gestation period of about 20 days. Young pocket gophers usually begin dispersing from the natal burrow in June when they are about one-third grown.
Pocket gophers feed on a wide variety of vegetation but generally prefer plants, shrubs and trees and use their sense of smell to locate food. Most commonly they feed on roots and fleshy portions of plants they encounter while digging. However, they sometimes feed above ground, venturing only a body length or so from their tunnel opening. Feed holes can be identified by the absence of a dirt mound and by a circular band of clipped vegetation around the hole. Gophers also will pull entire plants into their tunnel from below. In snow-covered regions, gophers can feed on bark several feet up a tree by burrowing through the snow. Many trees and shrubs are clipped just above ground, especially under snow cover.
Coyotes, domestic dogs and cats, foxes, badgers, long-tailed weasels, skunks, rattlesnakes, and bobcats capture gophers at their burrow entrances.
Pocket gophers often invade yards and gardens, feeding on many garden crops, ornamental plants, vines, shrubs and trees. There is extensive literature on how to trap and get rid of pocket gophers, yet these creatures play an important ecological role. Their tunnels are built and extended, then gradually fill up with soil as they are abandoned. The soil thus becomes mellow and porous after being penetrated with burrows. In mountainous areas, snowmelt and rainfall are temporarily held in gopher burrows instead of running over the surface, where they are likely to cause soil erosion. Surface mounds created by gophers also bury vegetation deeper and deeper, increasing soil quality over time. In addition, fresh soil in the mounds provides a fresh seedbed for new plants, which may help to increase the variety of plants on a site.
The name “gopher” has been used by “gophersport.com,” a company which sells physical education equipment, and a “Gopher protocol” which is an internet protocol designed for distributing, searching, and retrieving documents. Minnesota is the “gopher” state and “Goldy Gopher” is the mascot for the University of Minnesota.
Breckenridge resident Dr. Joanne Stolen is retired from teaching microbiology Rutgers University, and has taught classes at CMC. She is now pursuing a career in art, specializing in nature and many of the animals she writes about. Her work can be seen locally.
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