Appendix B: Control tips for common nuisance species in New York
Woodchucks or groundhog (Marmota monax)
Click here for "Wildlife Damage Management Fact Sheet Series--Woodchucks" from Cornell University
20–27" long, excluding tail; 5–12 pounds.
Signs of their presence:
- Adults often seen basking in the sun, in a grassy area, on a fence post,
stone wall, large rock, or fallen log—always near its burrow.
- Sounds: Occasional sharp whistles and low churrs, given at times of danger.
- Odor is distinctive. Will often see flies around an active burrow.
- Scat: Rarely seen (woodchucks excavate a privy off their main burrow).
- Evidence of their feeding: Chewed wood. Chewing on fresh plants similar
to that of rabbits; difficult to pin on woodchucks without supporting evidence.
- Dens: Will see a large mound of dirt and stones by the main entrance to
their burrow; the secondary entrances, which were dug from the inside, generally
don't have a dirt mound by their opening. Well-worn trail from entrance to
entrance, or to the garden.
Herbivore. Woodchucks eat succulent grasses, weeds, clover, fruits (apples,
cherries, pears), berries, field and garden crops (cabbage, lettuce, beans,
peas, carrots, alfalfa, soybeans), and ornamental plants (they love phlox).
They'll climb trees to take fruits such as cherries, apples, and pears.
Typical activity patterns:
Social style: Generally solitary.
Daily activity: Diurnal, most active in the
early morning and evening. They rely on dew as their water source. Woodchucks
have good eyesight, and are good swimmers. They'll climb trees up to a height
of about 20 ft, although more usually, they keep to 8–12 ft.
Hibernator? Yes. Hibernates deeply from the time of the first heavy frost
through early spring. Occasionally hibernates in small groups.
Distribution in NY and the Northeast: Everywhere.
Habitat: Meadows, woodlots, hay fields, pastures, hedgerows, idle fields,
parks, suburbs. Dens usually found in open fields; near fence rows or woodland
edges; under barns, sheds, porches, decks, stone walls, and wood piles.
Territory and home range: Territorial. Woodchucks
may skirmish to establish dominance. Subordinate woodchucks avoid dominant ones.
Home ranges overlap and are usually small. Woodchucks rarely travel more than
50 yards from their den, even to feed. Their burrows can be 2–5 feet deep
and as much as 60 feet long. There are usually 2 or 3 (but perhaps as many as
5) entrances, possibly including a well-hidden, straight-down "plunge hole".
Pair bonding style: Polygamous. Females raise young alone.
Breeding dates: Late February through March.
Birthing period: Late March to early May. Gestation takes about 31 days.
Litter size: 3–4.
Weaning dates: at 5–6 weeks.
Amount of time young remain with parents beyond
weaning date: Young stray from burrow alone at 6–7 weeks, mid-June
to early July. Mother drives young from her burrow by July.
Common nuisance situations:
Time of year: Calls peak in July and August, although their damage may begin
in spring and last into the fall.
What are they doing?
- Feeding, or just filing down their front teeth, which never stop growing.
Woodchucks raid gardens, fields, lawns, orchards, nurseries, and may gnaw
or claw on shrubs and fruit trees. Occasionally chew on outdoor furniture,
decks, and siding while scent-marking or filing their teeth.
- Marking their territories: They may strip off the bark at the base of a
tree that's near their burrow entrance.
- Burrowing. Look for burrow entrances among shrubs near vegetable and ornamental
gardens; under woodpiles, brush piles, and stone walls; under sheds, porches,
decks, and crawl spaces. Burrows in fields may damage agricultural equipment,
while those in pastures may trip livestock, resulting in injuries.
- Disease risks: Low. Mange, rabies (rarely), raccoon roundworm.
Legal status in New York:
Just when you thought it was all over, year-old woodchucks will occupy abandoned
burrows. You can try filling in the burrows, but they may re-open the holes.
Remove artificial food sources and shelter:
- Remove brush piles and debris, and keep areas well-trimmed.
Protect vulnerable crops:
- Erect a "rat wall" fence around gardens and fields. Make sure
the woodchucks can't climb over or dig under this barrier. Use 1–1 1/2"
chicken wire. The fence must be 4 feet high and buried 1 foot deep; if you
prefer, you can bury it only 1–2" down, if you bend the edge outward
into a "L" shape that sticks out at a 90° angle to prevent the
woodchucks from burrowing underneath it. Also bend the top 15" of the
fence out at a 45° angle to keep them from climbing over it, or add an
electric wire strung 4–5" above ground level, and 4–5"
from the outside of the fence.
- Another modification of the rat wall design. Use 2 × 4" welded
wire that's 2 ft. high, bottom buried in the L-shaped shelf as described above.
String an electric wire across the top of the fence. (Durable and effective
but more expensive.)
Keep them from denning under buildings:
First step: Remove any current residents. Exclude them with a one-way door
when young are old enough to be mobile.
If this is a preventive action, or there are no young present, can:
- Screen areas under decks, porches, and houses with the rat wall fence,
as described above. Attach the top of the fence to the structure.
If young are present, remove the entire family before blocking the entrance
to their den:
- If the young are older and mobile, install a one-way door over the entry
hole. They'll leave but won't be able to re-enter.
- Trap and release strategies to reduce the risk of orphaning wildlife: The
best way to prevent orphaning is to convince your customers to wait until
the young are mobile before removing, repelling, or excluding the family from
the site. If that's unacceptable, you can try to capture and remove both the
female and all of her young and hope that she will retrieve them and continue
to care for them.
- Capture the mother and young. Cover cages during transport to minimize
stress. Release them on-site, preferably in the morning.
- Place the female and young in a release box. Many NWCOs use a simple cardboard
box, others use a wooden nest box, such as a wood duck box, and some prefer
plastic boxes. Use a larger box with a 7" hole. (One NWCO recommends
a 2 × 2 × 1 ft. box.)
- Make sure the animal cannot immediately get out of the box by covering
the hole. Then move them to a quiet place outdoors. Remove the cover so the
female can get out of the box. Another option is to build a box with a sliding
door. Leave the door open about an inch, to keep the heat inside but make
it easy for the female to slide it fully open so she can retrieve her young.
- Some NWCOs prefer to use heated release boxes. Use heat when appropriate,
and make sure that the box doesn't get too hot. You may want to provide heat
in just one area. Also, assume that if you put something in the box, they
will chew on it. Don't give them access to anything that they shouldn't eat,
such as wires. That means that if you choose to use a household heating pad
as the heat source, make sure the animals can't reach the wires. To avoid
that problem, one NWCO builds his boxes with a double floor, placing the heating
pad in the space between the floors. Other options for heat sources include
microwaveable heating pads and warm soapstones.
- If you can't catch the female, put the young in the release box and locate
it as close to the entry site as possible.
- Cover the hole to the burrow with a soft plug to make sure that no woodchucks
are still using it. Check the next day to see if the young are still there.
If so, they've probably been abandoned. There hasn't yet been enough research
on this technique, so its effectiveness is unknown. It's likely to be more
effective with older, more experienced females; younger females might abandon
their young more readily.
- Cage trap should be at least 10x10x24". Double door traps should be
at least 10 × 10 × 30".
- Conceal the trap, using grass or canvas.
- Choose the size of trap based on the size of the burrow's hole, but realize
that woodchucks can wreck a smaller trap.
- Foothold traps, #1 or 1 1/2.
- Bait with apples, cantaloupe, cabbage, carrots with their green tops, fresh
peas, or lettuce. Woodchucks may ignore the bait if food is plentiful. Or
use a trap that's already housed a woodchuck, because the scent will attract
other woodchucks, especially males.
- Check traps twice daily, and provide shade and protection from weather.
Woodchucks overheat easily.
- Clean brush away from the opening of the trap, or it may interfere with
- Can also set trap without bait, placing it directly in front of the hole.
Dig down a bit and use fencing to guide the woodchuck into the trap.
- Spring is the best time for control, when the adults are active but before
the young are born. It's also easier to see the burrows then, and other animals
are less likely to be inside. Woodchuck burrows provide shelter to several
- Body-gripping trap, #160, #220, #120, or a 5 × 5 Buckeye, placed at the entrance
to the burrow. To reduce the risk of catching pets or unintended wildlife,
cover the hole and the trap with a weighted box or hardware cloth. Another
option is to add a one-way trigger to the trap, so it only fires when the
woodchuck is leaving its burrow. See chapter five for details.
- Modify the trigger to help ensure a top-to-bottom strike (which is more
humane) and to prevent the woodchuck from refusing to enter the trap. Woodchucks
don't like to have anything brush against their eyes or whiskers, so separate
the trigger and center it on the bottom of the trap. Proper positioning helps
to ensure a cleaner, more humane catch.
Other lethal techniques:
- For NWCOs with a commercial pesticide applicator licenses: Carbon monoxide
gas cartridges, a registered product, may be used to kill woodchucks in their
burrows. These gas cartridges do pose a fire hazard so don't use them near
buildings, under sheds, or near stumps. They could ignite grass, buildings,
gasoline, and other flammable objects.
Preferred killing methods:
- CO2 chamber
- Lethal trap
- Shooting, using a shotgun, a .22 caliber rifle, or a centerfire rifle where
safe (target the head, if no rabies testing is needed, or the heart/lungs)
- Lethal injection of barbiturate, if possible
Acceptable killing methods:
- Stunning and chest compression
- Pesticides (carbon monoxide fumigants) for NWCOs with a commercial pesticide
Methods that don't work well, or aren't legal in New York:
- There aren't any registered repellents for woodchucks.
- Commercial deer and rabbit repellents, as well as some pesticides thought
to repel woodchucks, weren't that effective at keeping them away from crops.