Backyard Gardener: Managing pocket gophers
Pocket gophers (Thomomys spp.) are beneficial to wildland ecosystems because they loosen soils increase water infiltration, transport beneficial soil microbes and are prey for other animals. Pocket gophers can also be very destructive when they venture into gardens and landscapes.
Their activity always increases during fall and spring. Young are also born in spring and, once they are a few months old, they leave their mother’s burrow system and establish their own territories. To successfully manage pocket gophers in the garden, orchard or landscape, you should learn about their behavior and quickly respond when they are approaching areas where serious damage could occur.
Some people mistakenly think they have moles. However, moles are not known to exist in Arizona. Pocket gopher activity can be recognized by the fan-shaped mounds of loose soil they create when they push soil out of their burrow system. The soil mound will also have a smaller plug of loose soil in the center or to one side of it marking where the burrow has been closed off. Fresh mounds indicate feeding or nesting activity. Pocket gopher burrow systems can be very extensive, especially in areas where they have been present for long periods.
Pocket gophers are not protected under Arizona Law and may be controlled freely on private property. Trapping is the most effective pocket gopher control strategy for home gardeners. A minimum of two traps are needed. I prefer the wire body gripping traps. However, there are several other designs available. The two traps should have a two- foot piece of wire tied to each of them and both connected to a single wooden or steel stake. I also recommend using a steel probe to help in locating burrows. This can be a quarter-inch, smooth steel rod with a handle (available from Yavapai County Master Gardeners for $5).
To set traps, locate the area of recent activity (freshly excavated soil). The mounds will be connected to lateral tunnels that connect to a main tunnel. You can determine which direction the lateral tunnel goes by looking at the fan of loose soil. This is where the gopher pushed the soil above ground. The small plug will be where the burrow begins. However, these lateral tunnels are often backfilled with soil for a foot or so. Using your probe, follow the lateral back to the intersection where the lateral joins the main tunnel. After you think you’ve located the main tunnel, dig a hole to expose it.
Practice setting the traps to become familiar with them. Once you are comfortable setting the traps, use a spoon or trowel to clean out and expose each entrance of the exposed burrow. Set a trap and carefully insert it all the way into one tunnel entrance while holding the trigger to prevent it from deploying. Do the same in the other tunnel. Cover the exposed tunnels completely so that air drafts are eliminated.
Pocket gophers will push soil into the trap if they detect air movement. After setting traps, kick over all fresh soil mounds in the area so that any new activity can be easily detected. By setting traps in the main tunnel near the most recent activity, you will have the greatest probability of trapping the gopher as it travels through the burrow system.
Researchers have found baiting traps does not increase trapping success. Check your traps each day and reset them if you are not successful. After a few days, you may need to relocate the traps to an area with more recent activity.
If you catch one gopher per burrow system, you have probably taken care of the problem for that localized area. Gophers are solitary except when they are breeding or nursing young. Continue to trap until you no longer see new mounds then do your best to collapse or obliterate existing tunnels to prevent re-colonization from adjacent areas. Over time, your trapping success rate should improve as you learn by trial and error.
There are other methods of gopher control (toxicants, flooding, exclusion, natural enemies, habitat modification, weed control, etc.). These may also be employed in larger areas or in agricultural settings. Repellents and scaring devices are generally ineffective. Additional photos and references are included with the online edition (see URL below).
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Jeff Schalau is the county director/agent for Agriculture & Natural Resources, Yavapai County, and the interim county director, Mohave County University of Arizona Cooperative Extension.