Burrowing Rodent Information

Gophers, prairie dogs, and ground squirrels cost farmers and landscapers millions of dollars every year!

Burrowing Rodent Information

Gophers, prairie dogs, and ground squirrels cost farmers and landscapers millions of dollars every year!

Gophers, prairie dogs, and ground squirrels can cause production losses of 20-50 percent in pastures and alfalfa. Equipment breakdowns and dirt contaminated hay cause huge economic losses to the farmer. Trees and vines girdled and killed by gophers can destroy the economic viability of an orchard or vineyard. The PERC (Pressurized Exhaust Rodent Controller) is a new, environmentally friendly, cost effective system for significantly reducing burrowing rodent populations on large acreage farms. Residential homeowners as well as landscape professionals will appreciate the noninvasive control PERC provides.

Information about Prairie Dogs

Prairie dogs have increased exponentially in many states with ‘dog’ towns covering many square miles. Fortunately, the PERC system can help you control the issue.

When treating prairie dog burrows, the wand (usually extended with a 3/8″ pvc pipe replacing the 1/4″ probe) is inserted into the burrow and dirt is shoveled plugging the burrow. Field experience has established that the treatment time for each burrow is from 3 to 5 minutes. Every live burrow should be treated.

Quick Facts…

  • Three species of prairie dogs are found in Colorado.
  • Prairie dogs have at least one litter per year and 6-10 pups per litter.
  • Prairie dogs can damage rangeland and occasionally harbor plague.
  • Prairie dogs can carry 5 different diseases, each of which can be fatally transmitted to humans.

Prairie dogs occupy an estimated two million acres in North America. Three species of prairie dogs are found in Colorado. The black-tailed prairie dog lives on the eastern plains, the Gunnison prairie dog in the southwest third of the state, and the whitetailed prairie dog in the northwest third of the state.

Prairie dogs are relatively large burrowing ground squirrels that weigh 1-1/2 to 3 pounds and are 14 to 17 inches long. Prairie dogs have reddish fur, large eyes, short ears and broad round heads.


Biology and Social Organization

Prairie dogs form colonies commonly referred to as prairie dog towns. Small groups, generally composed of one adult male, three adult females and six offspring, defend their territory within the larger town. They live in burrows about 10 yards apart, 3 to 14 feet deep and 10 to more than 100 feet long. A mound 3 to 10 feet across and 1/2 to 1 foot high at the entrance of the burrow prevents water from rushing in and serves as a lookout station. A density of 35 black-tailed prairie dog mounds per acre is common, although up to 95 mounds have been reported. Burrow systems have one to three entrances. Black-tailed prairie dog numbers vary from about five per acre in late winter to 20 per acre after the birth of pups in spring. Spring densities can be as high as 35 per acre.

Prairie dogs are active only during the day. White-tailed and Gunnison’s prairie dogs hibernate from about October to March, depending on elevation. Black-tailed prairie dogs do not hibernate, but will stay below ground for several days during cold cloudy weather. They have one litter of three to eight young per year in March or April. The gestation period is 28 to 34 days. Pups venture above ground when they are five to six weeks old. . Most prairie dogs travel  two miles, but a few migrate up to six miles.

Prairie dogs are hosts for fleas, making them susceptible to bubonic plague. Plague is transmitted to humans via flea bites. Early symptoms of plague include swollen and tender lymph nodes, chills and fever. Early diagnosis and treatment is imperative. When walking through suspected plague areas, apply an insect repellent to socks and pant cuffs before tucking pants inside boots

Information about gophers

Quick Gopher Facts:

  • Solitary rodents that live one animal to a burrow system.
  • Burrow systems are kept closed with holes plugged by the gopher.
  • Gophers eat plant roots, especially alfalfa roots, damaging or killing the plants.
  • Gophers do not hibernate and are active year round. Mound building is most active in the spring and fall as well as after sprinkler irrigation.
  • Burrow systems are usually two tiered; that is subsurface burrows that lead to the mound or the surface for shallow root feeding. A lower burrow or lateral is from six inches to twelve inches deep (or deeper) and connects mounds and feeding laterals.
  • A single burrow system can be 600 lineal feet and have 100 cubic feet of air space to fill with fumigant.
  • In ideal conditions, gophers can have three litters a year with 2 to 6 pups per litter.
  • Sprinkler irrigation provides ideal conditions for gophers.
  • Gopher infestations can have 100 rodents or more per acre and can cause crop loss of a ton of hay per acre.
  • Machinery breakdowns from gopher mounds cause harvest delays as well as repair expenses.
  • Severe infestations that have depleted plant stands should probably not be treated, but worked up and replanted.
  • Young crop stands (2 to 5 years) can be profitably treated if crop stands have not been irreparably damaged.
  • Flooding can reduce gopher infestations, but if the gophers are not killed at the time of flooding, with shovels etc, they will continue to multiply and cause crop damage. Depth of water levels that will drown gophers will also cause crop loss of stands.

Additional Gopher Information:

UC Davis
Colorado State University

Gopher Treatment with PERC:

  • Old mounds should be harrowed or otherwise reduced prior to treatment.
  • First treatment can reduce gopher populations by 66 percent or more.
  • Population reduction of 95 percent can be achieved with two or three additional treatments after new mounds have surfaced.
  • Gophers will reinvade a field and occupy old burrows.
  • Maintaining clean gopher free field borders can limit re-infestation.
  • Light to moderate gopher infestations can be treated at a rate of 3 to 8 acres an hour.

Information about Ground Squirrels

Quick Ground Squirrel Facts:

  • Live in colonies with several ground squirrels per burrow system.
  • Holes are kept open.
  • Ground squirrels hibernate in the winter with males surfacing a couple weeks earlier than the females, usually in February.
  • Ground squirrel season extends from February till the food supply is exhausted, usually into August or September.
  • They will usually have one litter a year numbering from 4 to 10.
  • They eat green surface foliage and will denude the immediate area around their burrow openings.
  • They will forage up to 100′ from their burrow opening.
  • The Belding ground squirrel can multiply at a very rapid rate and can exceed 100 rodents per acre.
  • Holes can be part of a huge mound or partially hidden with no mound.
  • Mounds can be several feet in diameter, over 12″ high and packed very hard with squirrel traffic.
  • Main holes can be 12″ in diameter at the opening and burrows several feet deep.
  • Different holes and burrows within a colony may or may not be connected.

Additional Ground Squirrel Information:

UC Davis
California Ground Squirrel Info
Colorado State University
Animal Diversity Web

Ground Squirrel Treatment with PERC: 

  • Old mounds should be harrowed or otherwise reduced prior to treatment.
  • Populations can be reduced by 70 percent or more from first treatment.
  • Two or three subsequent treatments can reduce populations by 95 percent.
  • All active live holes must be treated and sealed with dirt.
  • Only fresh active open holes need be treated a second and third time.
  • Treating ground squirrels in hibernation is not successful.
  • Old infestations are difficult to treat due to the huge burrow complexes.
  • Economic viability of treatment has to be determined by the farmer/rancher.
  • New infestations can be totally eliminated with PERC treatments.


Information about Moles and Voles

Quick Mole Facts:

  • Solitary, one mole to the burrow system.
  • Insectivores-moles eat worms, grubs, etc.
  • Damage crops and turf by up rooting plants.
  • Mounds and raised burrow areas can cause machinery damage and are unsightly in landscaping.
  • Build two tiered burrow systems. A subsurface burrow is used for feeding and a lower burrow, laterals, from six to twelve inches deep is used to connect feeding burrows and waste dirt mounds.
  • Additional Mole Information:

Ohio State University

Mole Treatment with PERC:

  • Successful treatment demands that laterals are probed and filled with carbon monoxide.
  • Subsurface feeding burrows will not hold a high enough concentration of the fumigant gas to kill the mole.
  • Treat fresh digging only. Moles reuse lateral burrows, but they are also continually digging new burrows.
  • Persistence and multiple probes of the same burrow complex result in high levels of success.

Quick Vole (Field Mice) Facts:

  • The names vole and field mice are used for basically the same mouse. Different locals use either one or the other or both (my experience).
  • Voles live in colonies and can explode to very dense populations under favorable conditions.
  • They eat green surface vegetation (for the most part) and can eliminate any growth within a colony.
  • They have multiple holes within the colony that are kept open and may or may not be connected underground.
  • Voles or field mice will establish new colonies and under favorable conditions, adjacent colonies will expand till they overlap.

Additional Vole (Meadow Mice or Field Mice) Information:

UC Davis
University of Nebraska Vole Handbook

Vole (Meadow Mice or Field Mice) Treatment with PERC:

  • Though multi acreage treatment has not been done, individual colony treatment has proven successful.
  • Voles are very susceptible to carbon monoxide.
  • As many holes as possible within a colony should be fumigated; at the same time if possible.
  • Holes do not need be sealed off. The sensitivity of the animal to CO and its heavier than air property works in the applicator’s favor.

Prairie dogs, gophers, ground squirrels, moles, and voles Burrowing rodents cause major damage to land.

Pressurized Carbon Monoxide helps control destructive pests.