 |
| Figure
1. Pocket gophers (Northern pocket
gopher shown here) are stout-bodied rodents with small
ears and eyes and large clawed front paws. Their large
front teeth are used to loosen soil and rocks while digging,
as well as to cut and eat roots.
(Photo by Ty Smedes.) |
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|
In some areas,
the name gopher is applied to a variety of mammal species including
ground squirrels and moles. True pocket gophers are burrowing rodents
that get their name from their fur-lined cheek pouches, or pockets.
These pockets are used, like a squirrel’s, for carrying food.
However, the pockets on a gopher open on the outside and turn inside
out for emptying and cleaning.
Pocket gophers
are well-equipped for a digging, tunneling lifestyle, with large-clawed
front paws, small eyes and ears, and sensitive whiskers that assist
with movement in the dark (Fig. 1). Their pliable fur and sparsely
haired tails—which also serve as a sensory mechanism—help
gophers run backward almost as fast as they can run forward. Their
large front teeth are used to loosen soil and rocks while digging,
as well as to cut roots (Fig. 2).
The pocket
gopher’s short fur is a rich brown or yellowish brown, but
also may be grayish or closely resemble the local soil color.
Two species
of pocket gophers occur in Washington: the Northern pocket gopher
(Thomomys talpoides) is the smallest and most widespread,
occupying much of eastern Washington. Adults of this species measure
8 inches in length, including their 2-inch tail. A subspecies called
the Brush Prairie pocket gopher occurs in Clark County (see
“Legal Status”). The Mazama
(Western) pocket gopher (Thomomys mazama) is the only
pocket gopher in most of western Washington—in the Olympic
Peninsula and the southern Puget Sound area. Adults measure 8 inches
in length, including their 2½-inch tail (see “Mazama
Pocket Gopher Conservation”).
Pocket gophers
can be a problem for homeowners, but they actually benefit the soil
and vegetation in many areas. Unfortunately, the positive effects
are not as visible as the mounds pocket gophers create in lawns
and pastures.
Facts
about Washington’s Pocket Gophers
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|
| Figure
2. Lateral views the skull of a pocket gopher (a) and a
mole (b) show the differences in their teeth. A pocket gopher’s
teeth are adapted for gnawing on plant material, and a mole’s
long jaws and multiple teeth are adapted for consuming small
insects. (From Verts and Carraway, Land Mammals
of Oregon.) |
Food and
Feeding Habits
- Pocket
gophers breed from early spring to early summer, resulting in
one litter of three to seven young per year.
- The nest
chamber is located in the pocket gopher’s burrow system,
is about 10 inches in diameter, and is lined with dried vegetation.
- The young
develop quickly, remain in the nest for five to six weeks, and
then wander off above ground to form their own territories.
- Pocket
gophers are solitary except during the breeding season or when
females have young with them.
- Densities
of northern pocket gophers have been found to range from 2 to
20 gophers per acre, depending on food availability, species,
and ages of the gophers.
Mortality
and Longevity
- Coyotes,
domestic dogs and cats, foxes, and bobcats capture gophers at
their burrow entrances; badgers, long-tailed weasels, skunks,
rattlesnakes, and gopher snakes corner gophers in their burrows.
Owls and hawks capture gophers above ground.
- A deep
snowpack can result in high gopher mortality. If the snow melts
rapidly it saturates the ground and floods the burrows.
- Pocket
gophers live one to two years and the majority of the population
consists of young adults.
| The
Benefits of Pocket Gophers |
| A
typical pocket gopher can move approximately a ton of soil
to the surface each year. This enormous achievement reflects
the gopher’s important ecological function.
Their
tunnels are built and extended, then gradually fill up with
soil as they are abandoned. The old nests, toilets, and partially
filled pantries are buried well below the surface where the
buried vegetation and droppings become deep fertilization.
The soil thus becomes mellow and porous after being penetrated
with burrows. Soil that has been compacted by trampling, grazing,
and machinery is particularly benefited by the tunneling process.
In mountainous
areas, snowmelt and rainfall are temporarily held in gopher
burrows instead of running over the surface, where they are
likely to cause soil erosion.
Surface
mounds created by gophers also bury vegetation deeper and
deeper, increasing soil quality over time. In addition, fresh
soil in the mounds provides a fresh seedbed for new plants,
which may help to increase the variety of plants on a site.
Many
mammals, large birds, and snakes eat gophers and depend on
their activities to create suitable living conditions. Salamanders,
toads, and other creatures seeking cool, moist conditions
take refuge in unoccupied gopher burrows. Lizards use abandoned
gopher burrows for quick escape cover. |
Viewing
Pocket Gophers
Although pocket
gophers are active year-round and at all hours of the day, their
underground lifestyle makes them difficult to observe.
If you are
patient, you may be able to watch a pocket gopher feed above ground,
or see their food being taken underground. The Mazama pocket gopher
spends the most amount of time above ground, generally at night
and on overcast days.
When sitting
in a grassy area, keep your eyes and ears alert for the sight
and sound of a wiggling clump of grass, wild flowers, or similar
vegetation. You might see the entire plant slowly disappear below
ground, and a few minutes later, the same gopher may venture a
body length’s distance from its tunnel opening to alertly
feed or gather food.
 |
| Figure
3. The side view of a portion of a pocket gopher’s
burrow system showing the mound, the short, sloping lateral
tunnel, and the deeper main tunnel. (Drawing
by Jenifer Rees.) |
When gathering
food above ground, a pocket gopher will cut vegetation quickly,
cram as much as possible into its external pouches (or pockets),
and then disappear below ground. It may reappear in a few minutes,
gather more food, and disappear to consume the food underground
or store it away for later.
Pocket gophers
live in extensive burrow systems, which they use for locating
food, rearing young, storing food and droppings, and escaping
predators. Burrow systems are a closely regulated microenvironment,
and gophers will plug any openings in the system within 24 hours.
Evidence of a gopher’s burrow system includes mounds, soil
plugs, and winter soil casts.
Mounds
As a pocket
gopher tunnels, it loosens soil with its front legs. When digging
becomes difficult, it bites off chunks of earth or roots with
its incisors. The gopher then somersaults to turn around and push
the loose earth and other debris to the surface bulldozer style,
with its front feet and head. The excavated material is pushed
out of the exit tunnel to the front, right and left, creating
a fan-shaped or heart-shaped mound (Fig. 3). (See Table 1 for
a comparison of pocket gopher and mole mounds.)
The capacity
of pocket gophers to excavate tunnels is phenomenal and heavy
clay soil doesn’t deter them. Gophers may create several
mounds per day, especially during the seasons when the soil is
moist and easy to dig. In irrigated areas such as lawns, gardens,
and pastures, digging conditions may be optimal year-round, and
mounds can appear at any time.
Table
1. Differences between moles and pocket gophers.
Before setting out to control what you assume to be gopher
damage,
be sure to properly identify the animal causing the damage.
|
| Moles |
Pocket Gophers |
| Minute
eyes are often not visible. |
Small eyes
are clearly visible. |
| Muzzle
is long and tapering. |
Muzzle
is rounded. |
| The many
small teeth are not apparent. |
Orange,
chisel-like pairs of upper and lower incisors are apparent. |
| Mounds
are round when viewed from above. |
Mounds
are crescent- or heart-shaped when viewed from above. |
| Soil plug
is in the middle of mound and may not be distinct. |
Soil plug
is in the middle of the V shape or off to the side of the mound
and may leave a visible depression. |
| Tunnels
are often just beneath the surface, leaving a raised ridge. |
No tunnels
are visible from above ground. |
Tunnels
Pocket gopher
tunnels are 1¾ to 3½ inches in diameter, depending
on the size of the gopher digging the tunnel. Tunnels occur 4
to 12 inches below ground, whereas the nest and food storage chamber
may be as deep as 6 feet. Tunnels tend to be deeper in drier soils.
Short, sloping, lateral tunnels connect the main tunnel system
to the surface and are created for pushing dirt to the surface
and access to foraging on the surface (Fig. 3).
Soil Plugs
Tunnel exits
made by a pocket gopher are marked by a 1- to 3 inch circle of
disturbed soil, or a circular depression, called a “soil
plug.” Soil plugs occur where a gopher emerged to forage
or deposit soil, and then plugged up the hole on reentry. Plugs
are found at mounds or along the course of the burrow system.
Vegetation may be clipped around the soil plugs where a gopher
was foraging.
Winter
Soil Casts
Soil casts
are created because pocket gophers commonly backfill their previously
excavated tunnels with excess soil when they dig new tunnels.
Casts are the result of this excess soil being backfilled into
snow tunnels. When the snow melts, these then become apparent.
Castings are nearly always fragmented and in short sections. Only
a fraction of snow tunnels are backfilled with soil, so castings
represent only a fraction of the gopher’s winter work.
Preventing
Conflicts
The ecological
services of pocket gophers, which are substantial, are often not
appreciated, particularly when the animals make their presence
known by eating garden crops or damaging orchard or ornamental
trees.
For homeowners
and gardeners, gophers may be only an occasional (or seasonal)
nuisance in lawns and garden beds, and not a long-term problem
or threat. Where these animals are not so numerous as to be causing
heavy damage, they should be considered neutral.
The subspecies
Brush Prairie pocket gopher and the Mazama (Western) pocket gopher
are in decline and are, or soon will be, of conservation concern
(see “Legal Status” and “Mazama
Pocket Gopher Conservation”). The presence of one of
these species in an area where you plan to take action—chemical,
nonchemical, mechanical, or otherwise—could preclude use
of this action. Before moving forward with any type of control,
contact your local Fish
and Wildlife office.
The following
are suggestions for reducing conflicts. In cases where these methods
are not practical, contact your local County Extension Agent or
local Fish
and Wildlife office for further information.
Frightening
devices and repellents: Although many devices are commercially
available for use to frighten pocket gophers (vibrating stakes,
ultrasonic devices, pinwheels, etc.), gophers do not frighten
easily. This is probably because of their repeated exposure to
noise and vibrations from sprinklers, people and livestock moving
about, and lawnmowers and other power equipment. Note:
Be skeptical of commercial products and claims, and make sure
the manufacturer offers a money-back guarantee if the product
proves ineffective.
No repellents
currently available will reliably protect lawns or other plantings
from pocket gophers. Mothballs, garlic, spearmint leaves, predator
urine placed in tunnels—and a perimeter of mole plant or
castor bean planted around gardens—have all provided mixed
results. Such control strategies may be experimented with where
gophers are an occasional problem, but not a long-term threat.
 |
| Figure
4. Raised beds can be protected from gopher damage by screening
the bottom side with ½-inch mesh hardware cloth. (Drawing
by Jenifer Rees.) |
Barriers:
Constructing a barrier to keep pocket gophers from tunneling into
an area can be labor-intensive and costly; however, this approach
is recommended for small areas and areas containing valuable plants.
Flowerbeds and nursery beds can be protected by complete underground
screening of the sides and bottom. Raised beds with rock or wooden
side supports will only require bottom protection (Fig. 4).
Wire baskets
can be used to protect the roots of individual trees and shrubs.
These can be purchased from nurseries or farm supply centers,
or be homemade. Use a double layer of light-gauge wire, such as
1-inch mesh chicken wire for trees and shrubs that will need protection
only while young. Leave enough room to allow for a few years of
root development before the wire rots away.
Groups of
bulbs (gophers are reported not to eat daffodil bulbs) and other
plants needing long-term protection can be placed in baskets made
from ½-inch mesh hardware cloth, available from hardware
stores and building supply centers.
Large areas,
such as vegetable gardens, can be protected using an underground
gopher fence (Fig. 5) or a stone-filled trench. However, such
a below-ground barrier will only slow the movements of gophers
for a time; sooner or later the barrier will be breached since
gophers are capable of digging much deeper than 24 inches.
To add to
the life of underground barriers, spray on two coats of rustproof
paint before installation. Above-ground parts can also be painted
to blend in. Always check for utility lines before digging in
an area.
Several types
of barriers (plastic tubes, one gallon plant containers) are effective
at protecting aboveground parts of small plants, such as newly
planted conifers.
Gophers may
be deterred from chewing underground sprinkler lines or utility
cables by surrounding them with 6 to 8 inches of coarse gravel
1 inch or more in diameter.

Click
image to enlarge |
| Figure
5. A pocket gopher fence should be installed at least 24
inches below ground (or down to the hardpan or bedrock) and
6 inches above ground. Use a 36-inch wide roll of ½-inch
mesh hardware cloth. Before placing the hardware cloth perpendicularly
in the trench, the bottom 6 inches should be bent outward at
a 90-degree angle. Alternatively, fill a 10-inch wide by 24-inch
deep trench with gravel that is 1 inch or more in diameter.
Note: Such barriers will likely only work temporarily.
(Drawing by Jenifer Rees.) |
In situations
where gophers are gnawing on water lines or wires, or are burrowing
into dams and dikes, refer to Muskrats
for management recommendations.)
Flooding:
Pocket gophers can easily withstand normal garden or home landscape
irrigation, but flooding can sometimes be used to force them from
their burrows. The entire tunnel system will need to be quickly
and completely flooded to evict its tenets. Five-gallon buckets
of water poured in the hole will flood the area more quickly than
a running hose.
Flooding
has the greatest chance of succeeding if gophers are invading
the property for the first time. Where they are already well established,
their systems are too extensive.
For humane
reasons, concentrate this effort in late winter and early spring,
before gophers give birth. Be careful when attempting to flood
out a gopher near a building; doing so could damage the foundation
or flood the basement or crawl space.
Natural
control: A long-term way to help prevent conflicts is a combination
of natural and active control. Predators—including snakes,
dogs, coyotes, long-tailed weasels, and skunks—kill gophers.
In addition, attracting barn owls and other raptors, which prey
on young gophers when they disperse, may help control a gopher
population, particularly in rural areas. Encouraging these species,
or not discouraging them, may help control the gopher population.
Predators
alone won’t keep a gopher population below the levels that
cause problems in gardens and landscaped areas. Before removing
every gopher, they will move on to hunt at more profitable locations.
However, when combined with the other control techniques described
here, natural control can contribute to overall control.
Public
Health Concerns
Gophers are
not considered to be a significant source of any infectious disease
transmittable to humans or domestic animals.
Legal
Status
The subspecies
Brush Prairie pocket gopher (Thomomys talpoides douglasi)
of Clark County is a state candidate species, and the Mazama
(Western) pocket gopher (Thomomys mazama) of Thurston,
Pierce, and Mason Counties is a state threatened and federal candidate
species. Because only remnant populations of these subspecies
and species exist, people should not use lethal control
in these areas.
Elsewhere,
pocket gophers are unclassified and may be trapped or killed and
no special trapping permit is necessary for the use of live traps.
However, a special trapping permit is required for the use of
all traps other than live traps (RCW
77.15.192, 77.15.194;
WAC
232-12-142). There are no exceptions for emergencies and no
provisions for verbal approval. All special trapping permit applications
must be in writing on a form available from the Department
of Fish and Wildlife .
It is unlawful
to release a pocket gopher anywhere within the state, other than
on the property where it was legally trapped, without a permit
to do so (RCW
77.15.250; WAC
232-12-271).
Because legal
status, trapping restrictions, and other information about gophers
change, contact your local Fish
and Wildlife office for updates.
| Mazama
Pocket Gopher Conservation |
In
the south Puget Sound area, many populations of Mazama pocket
gopher have disappeared since the 1940s, and the species was
recently listed as a candidate for protection under the federal
Endangered Species Act.
Mazama
pocket gophers continue to decline in numbers in part because
of their small, local breeding populations. For many years
the species has persisted by continually recolonizing areas
after local extinctions have occurred; however, loss of habitat
to development, trapping by homeowners, and persecution by
domestic cats and dogs have probably stopped much of this
recolonization.
While
large populations of some pocket gopher species can recover,
the small and isolated populations of the Mazama pocket gopher
can be completely lost.
If Mazama
pocket gophers are to persist in the south Puget Sound area,
they will require protection and lands where management is
compatible with their needs. In addition, because Mazama gophers
occupy grassy areas near homes and private property, a heightened
level of tolerance will be required from those people who
share their territories. In addition, if gophers are to survive
in the suburbs, it may only be because homeowners are willing
to keep their cats indoors.
The last
records of Tacoma pocket gophers, T.m. tacomensis
were of individuals killed by domestic
cats. |
Additional
Information
Books
Hygnstrom,
Scott E., et al. Prevention and Control of Wildlife Damage.
Lincoln, NE: University of Nebraska-Lincoln, Institute of Agriculture
and Natural Resources, 1994. (Available from: University of Nebraska
Cooperative Extension, 202 Natural Resources Hall, Lincoln, NE
68583-0819; phone: 402-472-2188; also see Internet Site below.)
Maser, Chris.
Mammals of the Pacific Northwest: From the Coast to the High Cascades.
Corvalis: Oregon State University Press, 1998.
Verts, B.
J., and Leslie N. Carraway. Land Mammals of Oregon. Los Angeles:
University of California Press, 1998.
Internet
Resources
Burke
Museum's Mammals of Washington
Internet
IPM Resources on Vertebrate Pests (Oregon State University)
Prevention
and Control of Wildlife Damage
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