QUESTION: How can I rid my property of gophers? They are making mounds and destroying some trees and bulbs in my garden.
ANSWER: Pocket gophers are burrowing rodents, so named because they have fur-lined, outer pouches on each cheek that can be turned inside out to carry food. Pocket gophers are strict herbivores and any animal material in their diets appears to be accidental. These rodents feed on roots, bulbs, corms or rhizomes they encounter when digging. They can pull vegetation into their tunnels from down below. They will also venture out of their runs a body length or so into the open to feed on above ground plant material. Pocket gophers burrows are a system of tunnels totaling up to 200 yards with densities of 6 to 8 rodents per acre a high population. The main burrow is generally 2 to 3 inches in diameter, depending on the size of the occupant and is 4 to 18 inches beneath the soil surface depending on the soil type. Lighter textured sandy soils will have deeper burrows than heavier clay soils. The soils ability to withstand cave-ins determines burrow depth, although some parts of the burrow may be 5 to 6 feet deep. Deeper branches off of the main burrow are used for nests and food caches. Enlargements along the main burrow are usually feeding and resting stations Nests chambers are lined with dry grass and other plant materials. A less apparent requirement of burrow depth is the need for fresh air and exhaled gases to pass through the soil to and from the gopher's tunnel. Therefore, heavy clay soils or those that are continuously wet, diffuse gases poorly and are not suitable for gophers. The fan shaped mound of soil seen on the surface is the excavated soil that is pushed out of the main burrow through a lateral branch. Pocket gophers are usually solitary except during the breeding season. Gophers have 1 or 2 litters per year and average 3 to 4 babies per litter, but 1 to 10 may be born. Birth is usually from March through June after 18 or 19 days of gestation. Predators of pocket gophers that pursue them underground are weasels, perhaps spotted skunks, and several snakes including bull and rattlesnakes. Dogs and cats may dig or capture them above ground along with other similar wildlife.
Control: Exclusion cages may be made by using 1/4 to 1/2 inch mesh hardware cloth which are placed in the ground and planted into. Plastic netting placed under newly planted seed beds or bare root plants may slow gophers down. There are no registered chemical repellents other than moth balls which are ineffective. Also noise devices and plants reported to repel pocket gophers have proven to be ineffective. Gopher traps are effective if a gopher runs into one. They are placed in the burrow and should have a wire or twine tied to the trap and an above ground stake so it can be retrieved when a gopher is caught. Perhaps the best way to rid your garden is to use toxic baits. These are usually grains that have be coated with poison. Currently the anticoagulant chlorophacinone formulated with a 0.005% active ingredient is available. This product is placed on grain and then formed into small bars which are held together with a waxy material. Another poison is zinc phosphide (2% active ingredient) is also available as a grain bait.
The best way to find the burrow is with a pointed steel rod cane that is used by probing the area a foot or two away from a mound. Remember that the mound is a short lateral tunnel off of the main burrow where soil is removed from the burrow. When a burrow is found, the rod will go easily through the soil. Dig down to the tunnel, locating the burrow hole on each sides of the hole you dug. Place some bait in each burrow hole and cover the baited burrow hole with a weed or grass so that backfilled soil will not fall on top of the bait. Fill in the hole and then knockdown any of the soil mounds within a 10 to 15 foot radius of where you dug a hole. Come back in a week and see if there are new mounds and bait those. Over time you will get the pocket gophers under control.
Source: Controlling Pocket Gophers in New Mexico. New Mexico State University Extension Publication 400 L-2, pp. 5.