Gophers are useful animals in the wild as they aerate the soil, eat insects and mix surface soil layers, but they are a nuisance on the farm when conflict surfaces between the farmer and the gopher over land use. Their economic impact on the farm can be enormous from damaging roots of fruit trees to tunneling through hay fields.
Gophers spend most of their time building extensive burrow systems, which are 4 to 12 inches underground and contain over 500 tunnels. The gopher mound is a unique shape, which extends laterally across the surface in the shape of a fan with plugs or dents placed at the end of the pile. These mounds can range from 12 to 24 inches in diameter and 4 or more inches in height.
Trapping is an effective non-toxic control method on small acreages. The most common type of gopher trap is the u-shaped, spring-type Macabee trap. Find the main runway of the tunnel by poking around in the fresh mounds. You know you have found the main runway when the probe sinks 4 to 12 inches into the ground. It is important to locate the main runway as gophers may not return to lateral tunnels for some time. Dig an opening into the tunnel and place two traps. Attach a wire to each and anchor with a flag for relocation. Leave the hole open as the gopher will return when he senses his burrow has been disturbed. When he comes back to cover the hole, the gopher will trip the trap. The best time to trap is in the fall and spring when gophers are most active. Check traps often and reset when necessary. If you do not catch a gopher within a few days, move the trap to a different location.
Using barn owls to control gophers is an option as well. Installing barn owl boxes will encourage barn owls to make their home on the farm. While barn owls prey on gophers, their habit is to range far from their nesting boxes, so using them as your main control is somewhat unreliable. When a single gopher is damaging an entire farm or crop quickly, quick fixes like trapping or baiting are necessary.
Poison baits are also available for gopher control, but the small farmer must take precautions not to affect other animal populations. Gopher baits contain strychnine and are very effective, but they can also be harmful to hawks, seed-eating birds, owls, and mammalian predators and scavengers including bobcat, foxes and coyotes. When applying bait into a main runway tunnel, make sure not to spill any on the soil surface and close up burrow holes after application. Make three to five bait placements per cluster of fresh mounds. Bait in the spring when gopher food is in low supply.
There are several other methods for controlling gophers including flood irrigating, exclusion, habitat modification and tunnel blasting, but trapping and baiting are the most common. For more information on gopher control as well as vole, mole and squirrel control, go to the OSU Extension catalog for publications on all of these small farm pests.
Sources: Controlling Pocket Gopher Damage to Conifer Seedlings OSU EC1255, Controlling Pocket Gopher Damage to Agricultural Crops OSU EC1117, Pocket Gophers UC Pest Notes 7433