Woodchuck
Woodchuck Facts
Control Methods
Exclusion
-
Buried welded or woven wire fences.
Single-strand electric fences.
Frightening Devices
-
Scarecrows and other effigies.
Repellents
Toxicants
Gas cartridges
Trapping
-
Live traps.
- No. 2 leghold traps.
- Conibear® traps.
Shooting
-
Effective where legal and safe.
Identification
The woodchuck (Marmota monax, Fig.
1), a member of the squirrel family, is
also known as the “ground hog” or
“whistle pig.” It is closely related to
other species of North American marmots.
It is usually grizzled brownish
gray, but white (albino) and black
(melanistic) individuals can occasionally
be found. The woodchuck’s compact,
chunky body is supported by
short strong legs. Its forefeet have
long, curved claws that are well
adapted for digging burrows. Its tail is
short, well furred, and dark brown.
Both sexes are similar in appearance,
but the male is slightly larger, weighing
an average of 5 to 10 pounds (2.2 to
4.5 kg). The total length of the head
and body averages 16 to 20 inches (40
to 51 cm). The tail is usually 4 to 7
inches (10 to 18 cm) long. Like other
rodents, woodchucks have white or
yellowish-white, chisel-like incisor
teeth. Their eyes, ears, and nose are
located toward the top of the head,
which allows them to remain concealed
in their burrows while they
check for danger over the rim or edge.
Although they are slow runners,
woodchucks are alert and scurry
quickly to their dens when they sense
danger.
Range
Woodchucks occur throughout eastern
and central Alaska, British Columbia,
and most of southern Canada. Their
range in the United States extends
throughout the East, northern Idaho,
northeastern North Dakota, southeastern
Nebraska, eastern Kansas, and
northeastern Oklahoma, as well as
south to Virginia and northern Alabama.
Habitat
In general, woodchucks prefer open
farmland and the surrounding
wooded or brushy areas adjacent to
open land. Burrows commonly are
located in fields and pastures, along
fence rows, stone walls, roadsides, and
near building foundations or the bases
of trees. Burrows are almost always
found in or near open, grassy meadows
or fields. Woodchuck burrows are
distinguished by a large mound of
excavated earth at the main entrance.
The main opening is approximately 10
to 12 inches (25 to 30 cm) in diameter.
There are two or more entrances to
each burrow system. Some secondary
entrances are dug from below the
ground and do not have mounds of
earth beside them. They are usually
well hidden and sometimes difficult to
locate (Fig. 3). During spring, active
burrows can be located by the freshly
excavated earth at the main entrance.
The burrow system serves as home to
the woodchuck for mating, weaning
young, hibernating in winter, and protection
when threatened.
Food Habits
Woodchucks prefer to feed in the early
morning and evening hours. They are
strict herbivores and feed on a variety
of vegetables, grasses, and legumes.
Preferred foods include soybeans,
beans, peas, carrot tops, alfalfa, clover,
and grasses.
General Biology,
Reproduction, and
Behavior
Woodchucks are primarily active
during daylight hours. When not feeding,
they sometimes bask in the sun
during the warmest periods of the
day. They have been observed dozing
on fence posts, stone walls, large rocks,
and fallen logs close to the burrow
entrance. Woodchucks are good
climbers and sometimes are seen in
lower tree branches.
Woodchucks are among the few mammals
that enter into true hibernation.
Hibernation generally starts in late fall,
near the end of October or early
November, but varies with latitude. It
continues until late February and
March. In northern latitudes, torpor
can start earlier and end later. Males
usually come out of hibernation before
females and subadults.
Males may travel long distances, and
occasionally at night, in search of a
mate. Woodchucks breed in March
and April. A single litter of 2 to 6 (usually
4) young is produced each season
after a gestation period of about 32
days. The young are born blind and
hairless. They are weaned by late June
or early July, and soon after strike out
on their own. They frequently occupy
abandoned dens or burrows. The
numerous new burrows that appear
during late summer are generally dug by older woodchucks. The life span of
a woodchuck is about 3 to 6 years.
Woodchucks usually range only 50 to
150 feet (15 to 30 m) from their den
during the daytime. This distance may
vary, however, during the mating season
or based on the availability of
food. Woodchucks maintain sanitary
den sites and burrow systems, replacing
nest materials frequently. A burrow
and den system is often used for
several seasons. The tunnel system is
irregular and may be extensive in size.
Burrows may be as deep as 5 feet (1.5
m) and range from 8 to 66 feet (2.4 to
19.8 m) in total length (Fig. 3). Old burrows
not in use by woodchucks provide
cover for rabbits, weasels, and
other wildlife.
When startled, a woodchuck may emit
a shrill whistle or alarm, preceded by a
low, abrupt “phew.” This is followed
by a low, rapid warble that sounds
like “tchuck, tchuck.” The call is usually
made when the animal is startled
at the entrance of the burrow. The primary
predators of woodchucks
include hawks, owls, foxes, coyotes,
bobcats, weasels, dogs, and humans.
Many woodchucks are killed on roads
by automobiles.
Damage
On occasion, the woodchuck’s feeding
and burrowing habits conflict with
human interests. Damage often occurs
on farms, in home gardens, orchards,
nurseries, around buildings, and
sometimes around dikes. Damage to
crops such as alfalfa, soybeans, beans,
squash, and peas can be costly and
extensive. Fruit trees and ornamental
shrubs are damaged by woodchucks
as they gnaw or claw woody vegetation.
Gnawing on underground power
cables has caused electrical outages.
Damage to rubber hoses in vehicles,
such as those used for vacuum and
fuel lines, has also been documented.
Mounds of earth from the excavated
burrow systems and holes formed at
burrow entrances present a hazard to
farm equipment, horses, and riders.
On occasion, burrowing can weaken
dikes and foundations.
Legal Status
In most states, woodchucks are considered
game animals. There is usually no
bag limit or closed season. In damage
situations, woodchucks are usually not
protected. The status may vary from
state to state, depending on the control
technique to be employed. Consult
with your state wildlife department,
USDA-APHIS-Animal Damage Control
representative, or extension agent
before shooting and/or trapping problem
individuals.
Damage Prevention and
Control Methods
Exclusion
Fencing can help reduce woodchuck
damage. Woodchucks, however, are
good climbers and can easily scale
wire fences if precautions are not
taken. Fences should be at least 3 feet
(1 m) high and made of heavy poultry
wire or 2-inch (5-cm) mesh woven
wire. To prevent burrowing under the
fence, bury the lower edge 10 to 12
inches (25 to 30 cm) in the ground or
bend the lower edge at an L-shaped
angle leading outward and bury it in
the ground 1 to 2 inches (2.5 to 5 cm).
Fences should extend 3 to 4 feet (0.9 to
1.2 m) above the ground. Place an electric
wire 4 to 5 inches (10 to 13 cm) off
the ground and the same distance outside
the fence. When connected to a
UL-approved fence charger, the electric
wire will prevent climbing and
burrowing. Bending the top 15 inches
(38 cm) of wire fence outward at a 45o
angle will also prevent climbing over
the fence. Fencing is most useful in
protecting home gardens and has the
added advantage of keeping rabbits,
dogs, cats, and other animals out of
the garden area. In some instances, an
electric wire alone, placed 4 to 5 inches
(10 to 13 cm) above the ground, has
deterred woodchucks from entering
gardens. Vegetation in the vicinity of
any electric fence should be removed
regularly to prevent the system from
shorting out.
Frightening Devices
Scarecrows and other effigies can provide
temporary relief from woodchuck
damage. Move them regularly and
incorporate a high level of human
activity in the susceptible area.
Repellents
None are registered.
Toxicants
None are registered for woodchuck
control.
Fumigants
Gas cartridge (carbon monoxide).
The most common means of woodchuck
control is the use of commercial
gas cartridges. They are specially designed
cardboard cylinders filled with
slow-burning chemicals. They are
ignited and placed in burrow systems,
and all entrances are sealed. As the gas
cartridges burn, they produce carbon
monoxide and other gases that are
lethal to woodchucks. Gas cartridges
are a General Use Pesticide and are
available from local farm supply
stores, certain USDA-APHIS-ADC
state and district offices, and the
USDA-APHIS-ADC Pocatello Supply
Depot. Directions for their use are on
the label and should be carefully read
and closely followed (see information
on gas cartridges in the Pesticides and
Supplies and Materials sections).
Be careful when using gas cartridges.
Do not use them in burrows located
under wooden sheds, buildings, or
near other combustible materials
because of the potential fire hazard.
Gas cartridges are ignited by lighting a
fuse. They will not explode if properly
prepared and used. Caution should be
taken to avoid prolonged breathing of
fumes.
Each burrow system should be treated
in the following manner:
1. Locate the main burrow opening
(identified by a mound of excavated
soil) and all other secondary
entrances associated with that burrow
system.
2. With a spade, cut a clump of sod
slightly larger than each opening.
Place a piece of sod over each
entrance except the main entrance.
Leave a precut sod clump next to
the main entrance for later use.
3. Prepare the gas cartridge for ignition
and placement following the
written instructions on the label.
4. Kneel at the main burrow opening,
light the fuse, and immediately
place (do not throw) the cartridge
as far down the hole as possible.
5. Immediately after positioning the
ignited cartridge in the burrow,
close the main opening or all openings,
if necessary, by placing the
pieces of precut sod, grass side
down, over the opening. Placing the
sod with the grass side down prevents
smothering the lit cartridge.
Make a tight seal by packing loose
soil over the piece of sod. Look
carefully for smoke leaking from the
burrow system and cover or reseal
any openings that leak.
6. Continue to observe the site for 4 to
5 minutes and watch nearby holes.
Continue to reseal those from which
smoke is escaping.
7. Repeat these steps until all burrow
systems have been treated in problem
areas.
Burrows can be treated with gas cartridges
at any time. This method is most
effective in the spring before the young
emerge. On occasion, treated burrows
will be reopened by another animal
reoccupying the burrow system. If this
occurs, retreatment may be necessary.
Aluminum Phosphide. Aluminum
phosphide is a Restricted Use Pesticide
and can be applied only by a certified
pesticide applicator. Treatment of burrow
systems is relatively easy. Place
two to four tablets deep into the main
burrow. Plug the burrow openings
with crumpled newspapers and then
pack the openings with loose soil. All
burrows must be sealed tightly but
avoid covering the tablets with soil.
The treatment site should be inspected
24 to 48 hours later and opened burrows
should be retreated.
Aluminum phosphide in the presence
of moisture in the burrow produces
hydrogen phosphide (phosphine) gas.
Therefore, soil moisture and a tightly
sealed burrow system are important.
The tablets are presently approved for
outdoor use on noncropland and
orchards for burrowing rodents. Tablets
should not be used within 15 feet
(5 m) of any occupied building or
structure or where gases could escape
into areas occupied by other animals
or humans. Storage of unused tablets
is critical — they must be kept in their
original container, in a cool, dry,
locked, and ventilated room. They
must be protected from moisture,
open flames, and heat.
The legal application and use of aluminum
phosphide for woodchuck control
may vary from state to state.
Check with your state pesticide registration
board, USDA-APHIS-ADC
representative, or extension agent
when considering use of this material.
Aluminum phosphide should always
be applied as directed on the label.
Trapping
Steel leghold and live traps. Traps
may also be used to reduce woodchuck
damage, especially in or near
buildings. Both steel leghold and live
traps are effective. Trapping should be
used in areas where gas cartridges or
aluminum phosphide may create a fire
hazard or where fumes may enter
areas to be protected. Woodchucks are
strong animals and a No. 2 steel trap
is needed to hold them. Before using
steel traps, consult your state wildlife
department or USDA-APHIS-ADC
representative for trapping regulations.
Steel traps should not be
employed in areas where there is a
possibility of capturing pets or
livestock.
Live trapping can sometimes be difficult,
but is effective. Live traps can be
built at home, purchased from commercial
sources (see Supplies and
Materials), or borrowed. Bait traps
with apple slices or vegetables such as
carrots and lettuce, and change baits
daily. Locate traps at main entrances
or major travel lanes. Place guide logs
on either side of the path between the
burrow opening and the trap to help
funnel the animal into the trap. Check
all traps twice daily, morning and
evening, so that captured animals may
be quickly removed. A captured animal
can be relocated to an area with
suitable habitat where no additional
damage can be caused. The animal can
also be euthanized by lethal injection
(by a veterinarian or under veterinarian
supervision), by shooting, or by
carbon dioxide gas.
Conibear® traps. Conibear® traps are
effective in some situations. A set in a
travelway, such as between a wood
pile and barn, can be very effective.
Sets can also be made at the main
entrance of the burrow system. Logs,
sticks, stones, and boards should be
used to block travelways around the
set and/or to lead the animal into the
set. No bait is necessary for Conibear®
sets. Conibear® 110s, 160s, and 220s
are best suited for woodchuck control.
Conibears® are well suited for use near
or under structures in which fumigants
and shooting present a hazard.
Conibear® 110s will handle young,
small animals, while 160s and 220s will
also handle larger adults.
Conibear® traps kill the animal quickly
and care should be taken to avoid
trapping domestic animals such as cats
and dogs. Some state or local laws prohibit
the use of Conibear® traps except
in water. Consult your state wildlife
department or USDA-APHIS-ADC
office for regulations.
Shooting
In many states, woodchucks are considered
game animals. Therefore, if
shooting is permitted, a valid state
hunting license may be required. In
some states there is no closed season,
nor is there usually any limit on the
number of woodchucks that can be
taken by hunters. If shooting can be
accomplished safely, landowners
and/or hunters can reduce or maintain
a low population of woodchucks
where necessary. Landowners and
hunters should agree on hunting
arrangements prior to initiating any
shooting activities. Another alternative
would be to have a professional
USDA-APHIS-ADC representative do
the job. He or she will be familiar with
legalities and techniques. Contracting
with a Animal Damage Control professional
would be especially valuable
when and where large numbers of
woodchucks are causing serious economic
losses. Shooting can be used as
a follow-up to other, more substantial
control activities.
Rifles with telescopic sights are commonly
used in the sport shooting of
woodchucks. A variety of calibers can
be used, but .22-caliber centerfire rifles
are most popular. Occasionally, shotguns
are used to eliminate woodchucks
that are causing damage. The
objective is to remove the animal as
humanely as possible without wounding
it. Shotgun gauge, range, and shot
size should be considered when using
this method. Use a 12-gauge with No.
4 to No. 6 shot. The range should be
within 25 yards (23 m).
Carefully assess the area behind and
around the target for safety. Pellets can
ricochet, causing injury or serious
damage in background areas. Use of a
rifle or shotgun should be conducted
only if good shooting conditions exist.
*The above information was taken from a University of Nebraska Web site with
express permission of Stephen Vatassel, wildlife damage project coordinator.
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