2-3 feet and around 8-15 pounds. However, some have been 40 pounds.
Signs of their presence:
Seeing the actual animals itself
Sounds: squealing, thumping of the male’s tail to attract the female, low-pitched grunts, snarls, and high-pitched cat like shrieks.
Evidence of their feeding: gnawing marks on the bark of branches. Nip twigs are small branches within reachable places in a tree with a sharp angled cut.
Tracks: the front feet are about 2.5 inches long and the hind feet are about 3.5 inches long. A long drag mark is left between the tracks from the tail.
Scat: pellets are around an inch long. Resembles a cashew nut.
House Damage: they may chew on the exposed wood on houses or sheds, especially if there is salt in the wood.
Herbivores. Depending on the time of year their diet will shift. In the spring and summer they will eat fruit, leaves, and buds off of plants. In the fall they will eat acorns and beechnuts. In the winter they will chew through the bark of a tree to get to the nutrient rich cambium; as well as the foliage on hemlock and spruce trees.
Typical activity patterns:
Social style: porcupines live a solitary life with the exceptions of winter and mating season. Through winter some porcupines will den together, up to 12 porcupines may den together. During the mating seasons porcupines will group together as many males may be competing for the same female.
Daily Activity: Mainly nocturnal, porcupines are slow moving creatures that travel from a den to a nearby tree to feed. On summer days they may be found in a tree, sometimes falling out of the tree and fracturing some bones.
Hibernator: Porcupines do not hibernate
Migrates: Porcupines do not migrate
In Washington state, porcupines can be found in forested areas or brushy wetlands throughout the state.
Porcupines live in coniferous or deciduous forest. They also live in a mixture of both types.
Territory and home range:
They are not territorial; however, one might chase others off from a tree it is feeding in during the winter. Porcupine males will fight over females. Winter home ranges are 6-12 acres while summer home ranges are 25-35 acres. Home ranges may overlap with others.
Pair bonding style: polygamous. Males will compete with each other for a female. Before the male breeds the female he will spray her with bursts of urine. Females raise the young.
Dens: Porcupines seek shelter in hollow trees, stumps, logs, caves, rocky ledges, and abandoned buildings to escape bad weather. Females will give birth in a den lined with branches and roots to a single baby porcupine.
Breeding dates: Mate in November and December. Gestation is a 205-217 day period.
Litter size: one, rarely two
Birthing period: June
Weaning dates: around 3 months old. However, at 14 days old a porcupine can survive on vegetation. At 6 months old, the porcupine is independent.
Common nuisance situations:
Time of year: all year long. During the different seasons, porcupines can cause different types of issues for a property owner.
During the winter their food source is not as abundant so their damage may be more easily seen. Some porcupines will feed on the same tree for a week and can end up killing the tree.
What are they doing?
Some dogs can get too close to a porcupine and end up with quills in its face, the animal was only defending itself.
During springtime as plants are budding, porcupines may find the landscaping to be a part of their diet.
Exposed wood on houses and sheds can be appetizing for the animal especially if there is salt on/in the wood.
In harsh weather, the attic or barn may become a suitable place to take shelter in.
Porcupines will feed on the buds of a tree, including prized fruit trees.
A foraging porcupine will eat the fruits, plants, and vegetables in your garden
They have been known to chew on tool handles, garden hoses, and tires.
Although not natural, porcupines may eat pet food that is left outside
Porcupines can find their way into the garbage from time to time if there are enticing smells
Porcupines do not carry many diseases that are worrisome to humans except for rabies.
Legal status in Washington:
Remove artificial food sources (pet food, compost, garbage)
Secure garbage can lids with straps and wait until the morning to put the garbage out.
Enclose compost piles in a framed box using hardware cloth; in a sturdy container, such as a 55-gallon drum; or in a commercial composter.
Feed pets inside and remove any food the is left outside before the night
Remove any fruit that has fallen in the yard
Protect Vulnerable Crops and Ornamental Plants
Wrap the base of small trees with 1” poultry wire. Wrap the wire 30 inches high to reduce their feeding damage
Fence off gardens with hardware cloth or welded wire mesh. At the top of the fence allow for 8 inches to come out at a 65- degree angle to stop the porcupine from just climbing over. An electric wire can be woven in through the top to be more effective. Build the fence before plants start to grow, as porcupines will not get the chance to establish the garden as a food source.
One scare device, the Critter Gitter®, combines a siren and flashing lights. It’s triggered by a motion detector. The device switches patterns, so it should be effective longer than a scare device that doesn’t vary.
Prevent Entry into Buildings
Patch any holes in the siding, not just on the first story as porcupines are excellent climbers.
Close any windows and doors that may have been left open
Trim back any trees that allow the porcupine access to the roof
Half-inch hardware cloth (or, even better, welded wire mesh) or galvanized sheet metal may be used to screen holes, decks, or other vulnerable areas. To protect the area underneath a deck or porch, create a “L”-shaped “rat wall.” Attach the hardware cloth to the bottom of the deck. Then bury the bottom 6–12″ deep, with a 12″ shelf that sticks out. Although porcupines do not dig much, other animals may try and get in thus creating a path for porcupines as well.
Attach a 3-ft wide band of metal flashing around trees at shin height to prevent porcupines from climbing the trees as well as feeding on the trees.
During the winter another band may be warranted as the snow level may allow porcupines to bypass the first sheet of metal.
If the female is denning in a building convince your customer to wait until they move out before removing, repelling, or excluding the family from the site.
Fence off access to under the porch or deck where porcupines may be chewing on exposed wood.
Porcupines have a unique defense mechanism all over their body, except on their stomach. The quills are hollow and expand as they absorb water and body heat.
Quills should be removed as soon as possible due to the fact that they can lead to infection and move deeper into your skin.
Since quills have a barb, a medical professional should remove them.
Quills should not be pulled straight out. Instead, they should be removed from the angle they went in. Twist the quill as it is being pulled out to prevent the barb from catching and tearing more skin.
If medical attention cannot be received right away clip the ends of the quill off. This will help reduce the swelling by relieving some of the pressure built up inside of the quill.
Cage traps (app. 10 x 12 x 32”) set near the area of damage or the den. Using a two-door cage trap may be best as it will allow the porcupine to come through one door and out the other. With all their quills it may be difficult and stressful for the animal to turn around.
Bait the trap with a fresh piece of wood with the bark still on, a rag saturated in a water salt solution, or fruit
Using a No. 220 or 330 Conibear place the trap near the den entrance. Make sure that only porcupines are using that pathway into the building or den area to prevent the capture and killing of a nontarget species
Preferred killing methods:
Shooting, use a shotgun with #6 shot or larger or a .22 caliber rifle. Target the head if rabies testing is not required or the hear/lungs.
Acceptable killing methods:
Stunning and shooting
Stunning and CO2 chamber
Fix holes in barns, sheds, or garages in which porcupines are using to access the building
Remove debris piles from your yard to make the area less attractive
Do not stack wood near the foundation of the building
Control Strategies that don’t work particularly well, or aren’t legal in Washington:
Put hot sauce on plants or spray them with pepper spray. Time consuming as sauce or spray has to be applied after rain.
Frightening techniques are not recommended as one might get quilled
Toxic baits are not recommended as porcupines rarely consume them
For information on pesticides follow the link https://agr.wa.gov/washington-agriculture/laws-and-rules/pesticides