Gophers in the Garden: Those Mountains in Your Garden Are NOT Mole Hills

Charles Cheyney

Extension Educator, Butte County

           

In the spring and early summer, we often get calls about "moles" in peoples' lawns, gardens, and alfalfa fields.  This identification is based on the large number of mounds created.  Not withstanding personal preference for naming critters, these crescent shaped eruptions of mulched up dirt are probably NOT mole hills, and they are not the burrows of ground squirrels.  They are mounds formed by pocket gophers, Mother Nature's fabulous subterranean engineers.  If you see the animals making the mounds often, they are probably ground squirrels, or if the volcanoes are circular with irregular lumps, you probably really do have moles.

           

Typical crescent pocket gopher mound

For most of the year gophers are solitary animals.  This means, that although you may have a lot of mounds in an area, there is probably only one gopher.  Figure 1 shows a map of a typical burrow system.  If you have mounds in several areas, you probably have several gophers.  An individual's burrow system may be 50 to 100 feet long and as wide, or more!

            Gophers feed on the roots and shoots of plants.  In some cases, they will actually pull entire plant underground from the bottom.  While gophers generally do not do a lot of damage, (unless it’s in your garden), there are basically four ways to control them.  All the methods require an understanding of the gophers burrow system.

            Gopher burrow systems are composed of a feeding tunnel at the depth where most feeding is occurring.  During the winter, when snow is present, the "tunnel" may actually be right at ground level, resulting in serpentine strands of mulched soil.  Below the feeding tunnel are food storage and "living quarters."  Periodically, the gopher turns perpendicular to their feeding runway, and burrow up to the surface at about a 45 degree angle.

            Toxic Bait.  Licensed operators may purchase strychnine baits, which must be applied below ground.  The operator uses a metal rod to probe for the main burrow, and deposits a spoonful of poison grain through the hole (Figure 2), and then plugs the hole.  If the rod punctures the bottom of the burrow, the gopher probably will not take the bait.  On large acreage with high populations, an automatic dispenser or artificial "burrow builder" may be used.

Figure 2. Using a metal rod or bait dispenser to probe for main tunnel.  When the probe intersects the runway it will suddenly drop 2 inches.  Probe is withdrawn and spoonful of bait dropped down hole, or the handle on the dispenser is activated and dispenses a predetermined amount of baits

  Smoke Bombs:  These work by suffocating the critter.  Effectiveness depends on: 1)having moisture in the burrow system to hold the gas in; 2)being able to plug all the openings; and 3) gassing the gopher before he knows what happened, since they will plug off the burrow if they have time.  The method is moderately expensive and moderately effective.  Repeat treatments are often necessary.

            Gopher Traps.  These are specially designed to be placed in the burrow system (Figure 4).  A shovel is used to open a hole that cuts across the main feeding burrow.  Traps are placed in both directions.  The open hole serves as the bait, since the gopher thinks he has an intruder, and will come quickly to the hole to plug it..  "Trap lines" can be very effective, and should be check frequently.  Be careful with Macabee gopher traps not to trap you fingers, which will really hurt!  Traps can be a very effective and environmentally safe method.  Once the traps are purchased, they may be used for years.  Be sure to "tie" them down with a light chair or wire, so a wounded animal cannot pack them away.

Figure 3. The Macabee gopher trap is one of several traps designed specifically for trapping pocket gophers..

Figure 4. Method of placing traps for pocket gophers.  Left, single trap in lateral tunnel; right, hole dug with shovel and two traps set in opposite directions in main tunnel.  Each trap should be fastened by wire or cord to a stake tall enough to be seen easily in the field.

             Flooding:  Like smoke bombs, flooding will seldom kill a gopher, but if the burrow system is pretty tight, and you surprise him, you may flush him to the top.  Once in the open, it will be up to you or your dog is dispatch the rascal!

            With all these methods, it is important to know which burrows or areas of the burrow system are active.  Always start by raking down or disturbing the existing mounds, and checking for new ones to see where to trap or bait.  If you are trapping be sure to check traps frequently and dispatch any wounded gophers humanely.  With toxicant and smoke bombs, be sure to read and follow all label instructions and precautions carefully.

More information about pocket gophers:

http://wdfw.wa.gov/living/gophers.html

http://icwdm.org/handbook/rodents/pocketgophers.asp

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7433.html

University of Nebraska Video