Animals That Cause Mounds in Yards

Talk about a rude homecoming: When you left for vacation, you had a level, well-manicured yard. By the time you returned, it had erupted in dirt mounds. They seem to have come out of nowhere, with no entrance holes to indicate digging intruders. The mysterious architects are two animals whose dearest wish is to be buried alive: pocket gophers and moles.

Crescent-shaped mounds higher and wider at one end than the other are the work of a pocket gopher. This curious creature has broad shoulders, outsized front claws, retractable lips and buck teeth that Bugs Bunny would die for.

Pocket gophers usually work alone, digging their network of tunnels with tooth and claw and pushing the excavated dirt to the surface. A single gopher:

produces up to three 1- to 1 1/2-foot-wide mounds per day, each standing from 4 to 6 inches high.

excavates more than 2 tons of dirt each year.

moves about in the system of burrows 6 inches to 1 foot beneath the soil's surface.

stores food in chambers up to 6 feet underground.

A gopher works most quickly in moist, loose soil such as that in garden beds or irrigated lawns. It tunnels day and night, eating the roots, tubers and bulbs it uncovers while digging.

If your flower or vegetable plants are disappearing overnight, a pocket gopher may be grabbing them by the roots and pulling them underground.

A yard sprouting miniature earthen volcanoes is host to a mole or small colony. Circular at their bases and tapered on the top, mole mounds measure from 6 inches to 2 feet across and from 2 inches to 8 inches tall.

Most yards host no more than one male or one or two female moles. Because earthworms supply up to 90 percent of the mole diet, the rich, moist, loose soil that earthworms love is their ideal habitat.

Moles have cylindrical, streamlined bodies, pointed snouts, enormous, paddle-shaped front paws and short, velvety fur that moves backward or forward as they change direction. In short, moles are born to tunnel.

They:

 construct mazes of surface tunnels 1 to 4 inches deep and up to 3 inches wide. The tunnels cause ridges that look as if a snake had been slithering beneath the soil.

 connect the surface tunnels to deeper runways, up to 40 inches underground and linked to nesting chambers.

 tunnel up to 1 foot per minute in loose or sandy soil.

Moles' surface tunnels are most common along artificial borders, such as landscape edgings and walkways.

At first glance, pocket-gopher and mole mounds seem to lack entrances. After excavating a new tunnel or burrow, however, the animals seal their mounds with soil plugs to keep out rainwater and predators. Gophers put plugs on one side, usually in the middle of the inwardly curved edge. Moles plug the mounds' centers, but the plugs are difficult to distinguish.