Pocket Gophers
Pocket gophers are burrowing rodents that get their name from the fur-lined external cheek pouches, or pockets, they use for carrying food and nesting materials. They are well equipped for a digging, tunneling lifestyle with powerfully built forequarters, large-clawed front paws, fine short fur that doesn't cake in wet soils, small eyes and small external ears, and highly sensitive facial whiskers to assist movements in the dark. An unusual adaptation is the gopher's lips, which can be closed behind the four large incisor teeth to keep dirt out of its mouth when it is using its teeth for digging.
IDENTIFICATION:
Although they are sometimes seen feeding at the edge of an open burrow, pushing dirt out
of a burrow, or moving to a new area, gophers for the most part remain underground in the
burrow system.
Mounds of fresh soil are the best sign of gopher presence. Mounds are formed as the gopher digs its tunnel and pushes the loose dirt to the surface. Typically mounds are crescent- or horseshoe-shaped when viewed from above. The hole, which is off to one side of the mound, is usually plugged. One gopher may create several mounds in a day. In non-irrigated areas, mound building is most pronounced during spring or fall when the soil is moist and easy to dig. In irrigated areas such as lawns, flower beds, and gardens, digging conditions are usually optimum year round and mounds can appear at any time.
BIOLOGY AND BEHAVIOR:
Pocket gophers live in a burrow system that can cover an area of 200 to 2,000 square feet.
The burrows are about 2.5 to 3.5 inches in diameter; feeding burrows are usually 6 to 12
inches below ground, whereas the nest and food storage chamber may be as deep as 6 feet.
Gophers seal the openings to the burrow system with earthen plugs. Short, sloping lateral
tunnels connect the main burrow system to the surface and are created during construction
of the main tunnel for pushing dirt to the surface.
Gophers do not hibernate and may be active at any hour of the day. Gophers usually live alone within their burrow system, except for females with young or when breeding, and may occur in densities of up to16 to 20 per acre.
Gophers reach sexual maturity at about 1 year of age and can live up to 3 years. Females produce one to three litters per year: in non-irrigated areas, breeding usually occurs in late winter and early spring, resulting in one litter per year, whereas in irrigated sites, up to three litters per year may be produced. Litters usually average five to six young.
Pocket gophers are herbivores, feeding on a wide variety of vegetation, but generally preferring herbaceous plants, shrubs, and trees to grasses. Gophers use their sense of smell to locate food. Most commonly they feed on roots and fleshy portions of plants they encounter while digging. However, sometimes they feed aboveground, venturing only a body length or so from their tunnel opening. Burrow openings used in this manner are called "feed holes. " They are identified by the absence of a dirt mound and a circular band of clipped vegetation around the hole. Gophers will also pull entire plants into their tunnel from below. In snow-covered regions gophers may feed on bark several feet up a tree by burrowing through the snow.
MANAGEMENT:
To successfully control gophers, the sooner you detect their presence and take control
measures, the better. Most people control gophers in lawns, gardens, or small orchards by
trapping them and/or by using poison baits.
Trapping
Trapping can be a safe and effective method to control pocket gophers. Several types and
brands of gopher traps are available. The most commonly used is a two-pronged pincher
trap, such as the Macabee trap, which is triggered when the gopher pushes against a flat
vertical pan. Another popular trap is the choker-style box trap.
To set traps, locate the main tunnel with a probe. Use a shovel or garden trowel to open the tunnel wide enough to set traps in pairs facing opposite directions. By placing traps with their openings facing in opposite directions, a gopher coming from either end of the burrow can be intercepted. The box trap is easier to use if you've never set gopher traps before, but setting it requires more excavation than if you are using the Macabee trap, an important consideration in lawns and some gardens. Box traps are especially useful when the diameter of the gopher's main burrow is small (less than 3 inches) because to use the Macabee-type wire traps, small burrows must be enlarged to accommodate them.
It is not necessary to bait a gopher trap, although some claim baiting gives better results. Lettuce, carrots, apples, or alfalfa greens can be used as bait. Place the bait at the back of a box trap behind the wire trigger or behind the flat pan of a Macabee-type trap. Wire your traps to stakes so they can be easily retrieved from the burrow. After setting the traps, exclude light from the burrow by covering the opening with dirt clods, sod, cardboard, or some other material. Fine soil can be sifted around the edges to ensure a light-tight seal. If light enters, the gopher may plug the burrow with soil, filling the traps and making them ineffective. Check traps often and reset them when necessary. If a gopher is not caught within 3 days, reset the traps in a different location.
Baiting with Toxic Baits
The key to an effective toxic baiting program is bait placement. Always place pocket
gopher bait in the main underground tunnel, not the lateral tunnels. After locating the
main gopher burrow with a probe, enlarge the opening by rotating the probe or inserting a
larger rod or stick. Following label directions, place the bait carefully in the opening
using a spoon or other suitable implement that is used only for that purpose, taking care
not to spill any on the ground surface. A funnel is useful for preventing spillage.
Strychnine-treated grain bait is the most common type used for pocket gopher control. This bait generally contains 0.5% strychnine and is lethal with a single feeding. Baits containing anticoagulants are also available. They require a large treatment so that the bait is available for multiple feedings. Although generally less effective than strychnine baits, anticoagulant baits are preferred for use in areas where children and pets may be present. When using either type of bait, be sure to follow all label directions and precautions.
After placing the bait in the main burrow, close the probe hole with sod, rock, or some other material to exclude light and prevent dirt from falling on the bait. Several bait placements within a burrow system will increase success. Tamp down existing mounds so you can distinguish new activity. If new mounds appear for more than 2 days after strychnine baiting or 7 to 10 days after anticoagulant baits have been used, you will need to rebait or try trapping.
Biological Control
Predators, including owls, snakes, cats, dogs, and coyotes, eat pocket gophers. In most
cases they are unable to keep pocket gopher populations below the levels that cause
problems in gardens and landscaped areas because just one gopher can cause considerable
damage. Predators rarely, if ever, remove every prey animal, but instead move on to hunt
at more profitable locations. In addition, gophers have defenses against predators. For
example, they can escape snakes in their burrows by rapidly pushing up an earthen plug to
block the snake's advance.
Recently there has been interest in the idea of attracting barn owls to an area for gopher control by installing nest boxes. Although barn owls prey on gophers, their habit of hunting over large areas, often far from their nest box, and their tendency to hunt areas with abundant prey, makes them unreliable for gopher control. When a single gopher, capable of causing damage rapidly, invades a yard or garden, a gardener cannot afford to wait for an owl to arrive. Effective action, usually trapping or baiting, must be taken immediately.
Follow-up
Once pocket gophers have been controlled, monitor the area on a regular basis for
reinfestation of the land. Level all existing mounds after the control program and clean
away weeds and garden debris so fresh mounds can be seen easily. It is important to check
regularly for reinfestation because pocket gophers may move in from other areas and damage
can reoccur within a short time. If your property borders wildlands, vacant lots, or other
areas that serve as a source of gophers, you can expect gophers to reinvade regularly. Be
prepared to take immediate control action when they do; it is easier, cheaper, and less
time-consuming to control one or two gophers than to wait until the population builds up
to the point where the gophers are causing excessive damage.