Information about Gophers

Got Gophers?

Extensive field experience by growers has demonstrated a kill rate in excess of 90% over a season’s use, with reductions of rodent populations by 66% to 75% in a single treatment.

Gophers or ground squirrels can cause production losses of 20%-50% in pastures and alfalfa.  Serious loses in nut orchards are economicaly not acceptible.

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 invention; in 2006 an environmentally friendly, cost effective system for significantly reducing burrowing rodent populations on large acreage farms. Excellent for alfalfa hay farming operations as well as for use on orchards, vineyards, and sports fields.

Custom Operators and landscape professionals, as well as their customers, will appreciate the noninvasive control PERC® provides.

PERC® is also a powerful compressor that can be used in the field.  Compressed and cooled exhaust (carbon monoxide) is safer than compressed air when used for blowing out equipment such as hay balers, where loose flammable material may come in contact with hot components.

Click the categories below for more information about gophers and other rodents!

 

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

What do Gopher Tunnels Look Like Underground?

Internet Center for Wildlife Damage Management

 

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 re-invade 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.

 

How to properly probe a gopher burrow:

Information about Ground Squirrels

“Pressurized exhaust systems that inject concentrated carbon monoxide into burrow systems are also legal for use in California. Of these devices, the Pressurized Exhaust Rodent Controller (PERC) machine has been extensively tested and has proven to be effective for the management of California ground squirrels.”  (Dr Roger Baldwin, University of California)

Quick Ground Squirrel Facts:

  • Live in colonies with several ground squirrels per burrow system.
  • Holes are kept open from early spring (February/ March) till late fall but closed during winter hibernation. (Squirrels in Northern habitats)
  • 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.
  • California ground squirrels are very destructive in vineyards and orchards and can cause severe financial losses due to fruit and nut damage and under ground cashes.
  • California ground squirrels are active year-round and can inhabit any area with mild winters.

Additional Ground Squirrel Information:

UC Davis

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 up to 100 percent on first treatment. (Dr Roger Baldwin, University of California).
  • 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.
  • 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.

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 exaust gas and 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.


Mole tunnel schematic

Biology and Behavior

Moles have cylindrical bodies with slender, pointed snouts, and short, bare, or sparsely haired tails. Their limbs are short and spadelike. Their eyes are poorly developed and their ears are not visible. The fur is short, dense, and velvety. Moles have one litter of three or four young during early spring.

Mounds and surface runways are obvious indicators of the presence of moles. The mounds are formed when moles push soil up to the surface from underground runways. The excavated soil may be in small chunks, and single mounds often appear in a line over the runway connecting them.

Surface feeding burrows appear as ridges that the mole pushes up by forcing its way through the soil. Some of the surface runways are temporary. More permanent tunnels are deeper underground and are usually about 2 inches in diameter and 8 to 12 inches below the surface. Moles are active throughout the year, although surface activity slows or is absent during periods of extreme cold, heat, or drought.

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 Dog Information:

The most common species of prairie dogs is the black tailed prairie dog.  It lives in colonies called towns and extend over thousands of acres.  The prairie dog is a member of the ground squirrel family.  There are 5 sub species of prairie dogs of which the black tailed prairie dog is the most common and most invasive.

  • Prairie dogs (PD’s) normally have one litter of 10 pups or more per year.
  • The black tailed prairie dog does not hibernate but when vegetation is not available, it will use stored body fat.
  • PD’s usually have one male, several females and young in a single burrow system.
  • PD’s will protect their burrow system from invasion of other PD’s.
  • PD’s build extensive burrow systems that are noted for their ‘chimneys’ of packed dirt. These chimneys can be very damaging to equipment and livestock.
  • PD’s prefer upland dry pastures but also inhabit perennial crop land. (alfalfa, grass hay and pastures.)

Treatment:

The PERC System has been used for over ten years treating PD burrows with proven success.  The preferred method is to replace the tip of the T-bar hand piece with the furnished 12” hose and clamp or threaded end.   The half inch hose and probe is inserted first with dirt shoveled to mark the treated burrow.  While it is on, insert the smaller 3/8” T-bar hand pieces with hose extensions in adjoining burrow openings.  ONLY TREAT ONE BURROW SYSTEM AT A TIME TO PREVENT DILUTION OF THE EXHAUST GAS BY TREATING MORE THAN ONE BURROW SYSTEM. (the 620 can treat two burrow systems at a time)

The large ½” probe will purge the air from the burrow and replace it with Exhaust gas in two or three minutes.  When the smaller probes are in place, turn off the half inch probe and turn on the smaller probes.  Treat all live holes even if gas is coming out of the hole.  Leave the smaller probes in place for an additional three minuets.

Treat only ‘live’ burrows.  If there is dirt or litter in the burrow, it most likely not a live burrow.

NOTICE:
Look for other occupants that might be living in PD burrows.  Burrowing owls are common in some areas and will be evident by ‘casts’ that are around the burrow opening.  Black foot ferrets, a protected species are also in PD burrows but impossible to know of their presence.  Snakes can also inhabit PD burrows.

If it is evident there is a occupant of a PD burrow other than the PD’s, it is advised that the burrow remain untreated and undisturbed.