J&T's Critter Care & Wildlife Education Center
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Porcupines
Porcupine
North American Porcupine
Erethizon dorsatum
Phylum: Cordata
Class: Mammalia
Order: Rodentia
Family: Erethizontidae
Genus: Erethizon
Species: dorsatum
Porcupines’ Latin name means to “irritate with back”.
Size
North American porcupines are approximately 2 to 3 & 1.5 long (25 – 31”) (73-78cm). Tail length is approximately 7-11” (17.5-28cm). Height at the shoulder is up to 12” (30cm).
The average weight of a male is 15-18lbs, although they have been recorded up to approximately 25lbs! Females average about 2lbs less than the males (about 0.9kg).
They are a nocturnal rodent, which explains why I never knew until just a few years ago we have them here in NY (OOPS!). They are
Porcupines are fascinating & totally intrigue me. This paper is months of research on my part, all though it may not look like much! They are one of the animals I plan to educate people about, as I have found some people see them as a nuisance. I have gathered information from various websites & books, etc., & will list them at the bottom.
Diet
Porcupines are Herbivores.
Like other herbivores, porcupines have bacteria in their digestive track that helps them to break down the cellulose & other items in their diet, that normal digestive items don’t break down well. Being an herbivore, the processes have an affect on the sodium metabolism of porcupines.
In the wild the porcupine feeds on leaves, twigs, & green plants, such as skunk cabbage & clover. It will eat buds & young leaves of willow & aspen until the tannin levels build up to high for the porcupine to tolerate. The porcupine also eats evergreen tree inner bark & needles, aquatic plants, grasses, buds, berries, seeds, flowers, nuts, grasses & other vegetation. It also likes yellow pine (west), white pine (great lakes area), hemlock (northeast), bark of maples (with the rising of the sap); catkins, leaves of alder, poplar, herbs, shrubs, such as, currant, rose, thorn apple, dandelion, violets; water vegetation, such as, lily & arrowhead; and beech masts.
In the winter, the porcupine primarily eats conifer needles & the tree bark of conifers & hardwoods. They like to eat the inner bark (phloem & cambium layers) of spruce & hemlock.
At zoos, porcupines are fed commercially prepared rodent diets, plus assorted vegetables, including yams, apples & carrots. Although, of the many I contacted, none had a North American Porcupine in their care.
Porcupines mainly forage for food at night, BUT the will come out during the day too.
Porcupines like to chew on wood tools that have human perspiration, assumably for the salt, & shed antlers for minerals, but they will also chew on non-salt items – which is just the indicator that they need to chew to help keep their teeth in check. As they are rodents, their teeth continually grow & they need to gnaw to keep them trimmed.
Porcupine populations from different areas eat different things (makes sense, huh?? J
In the Catskills, they enjoy Sugar Maples, young Beech Trees (not Canopy Beeches), Basswood, Apple & Aspen. They also eat the young Ash leaves, acorns & Beechnuts when available.
Porcupines in eastern forests feed on a variety of trees. In the winter, they mainly focus on foraging the phloem of the hemlock & sugar maple trees.
Porcupines in the
In
Porcupines of
The crucial nutritional component for a porcupine is nitrogen. Porcupines loose weight through winter because they largely on bark, twigs, & evergreen needles. These things are not good sources of nitrogen.
They will feed on numerous trees until tannin levels rise too high for the porcupine to tolerate any longer. Tannin is toxic to the porcupine.
Porcupines feed at night to take advantage of chemical changes in plants & leaves. There are additional nutrients available during the night-time metabolic processes of the plants. The porcupine is wise to take advantage of this.
Coloration & Appearance
It has black-yellowish-brown fur (black in the East & yellowish in the West). It has strong, short legs. It is an excellent tree climber & in fact, spends most of its time there. The soles of its feet are hairless & have little knobby bumps all over it. They have long, curved claws. They have small, round ears that are close to the head. Porcupines do not have canines. The main teeth everyone sees & would recognize their rodent characteristics are their incisors. The porcupine also has about 16 other large, flat teeth to chew & grind its food.
Quills
The big thing most people think of when you say porcupine, is the quills that it has. No, they can’t throw them at anyone (or anything!).Porcupines can have as many as 30,000 quills on their bodies!! The quill is a modified hair with a barbed tip on the end. Quills are solid at the base & tip. Inside the quill, there is a spongy matrix, which makes the quills rigid, yet light. Quills have a barb at the end & once entered into the skin, it hooks in, making it painful to extract the quill. The quills cover all parts of their bodies except for their stomachs, muzzles & legs. Their stomach is where they are most vulnerable to predators, who try to roll porcupines over, to get to their stomach. Their longest quills are on their rears, & their shortest being in their cheeks. The quills are used for the porcupine to defend itself.
When the porcupine feels threatened, it will turn its back toward the predator & swat with its tail. If an animal gets hit with the quills, they get embedded in the animal’s skin. The body heat of the animal makes the barbs expand. The longer they are in, the harder they are to remove! If a vital area of the animal is hit, it can die. Recently acquired quills can be easily removed with a pair of pliers. However, if there is a large number, or if they have worked in deeply, the animal will need to be taken to the vet to be anesthetized & have the quills removed. Cutting the ends off the quills releases air pressure they builds up from swelling, & may make for easier removal.
Porcupine quills have a natural antibiotic coating on them. It doesn’t mean that an infection will not occur, however, if they are not promptly taken care of! The natural antibiotic is more for the protection of the porcupine from what I have read thus far. In case it accidentally gets stuck with its own quills, or by an adversary’s quills in a fight.
Relaxed hair & quills will lay flat & point backwards. When threatened, the porcupine will draw up the skin of the back to expose quills facing in all directions. The porcupine will try to keep its back to its attacker & strike back & forth with its tail.
Porcupines have so many quills so that they are still able to protect themselves after encounters with predators. New quills will grow in place of the lost quills & they will be all white. They will remain attached in place until they are fully grown in. It can take anywhere from 2-8 months for new quills to grow in & replace the old quills that were lost.
Quills are usually 75mm long & 2mm wide.
On the NativeTech website listed below, by Tara Prindle, there is a cool scan of a quill with an electron microscope.
Dens/Hibernation
Porcupines den in caves, decaying logs & hollow trees – it doesn’t hibernate during the winter, but may den up during bad weather.
Senses/Vocalizations & Other Characteristics
The porcupine is a good swimmer. Its hollow quills help to keep it afloat.
The porcupine is VERY vocal, especially during mating season. They have a variety of calls.
They have excellent senses of hearing, taste & smell, but poor vision. (Maybe because of those tiny little eyes!)
Females are territorial & will exclude other females from their territory. Males territories will overlap.
Porcupines are solitary but may den up together in the winter. Several may share a den on a rotating basis & several may share the same den site at the same time. They will also gather with others, in about a group of a dozen or so, at nocturnal feeding in summer & fall.
When porcupines become stressed, they may produce a noxious odor, & chatter, or clack their teeth to tip off would-be predators, giving them plenty of warning.
Relatives
Cousins of the porcupine in
The North American Porcupine has prickly cousins in Africa & Asia too. The porcupine is not related to the hedgehog & the spiny anteater, however.
Predators
Some predators of the porcupine include the Fisher (Martes pennanti), Bobcat (Lynx rufus), Mountain Lion (Puma concolor), Coyote (Canis latrans), Lynx (Lynx canadensis), Wolf (Canis lupus), Wolverine (Gulo gulo) & Great Horned Owls (Bubo virginianus). The fisher is the best known porcupine hunter & is very good at it.
Life Cycle
Porcupines mate in late summer & early fall. They are very vocal during the breeding season. Males will often fight over females.
Heat lasts 8-12 hours & the female will recycle in 25-30 days if fertilization does not occur.
A single baby, weighing about 1-2lbs (0.5-10.kg) & measuring about 10” (25cm) long, is born 7 (205 – 215 days) months after mating. This is an unusually long gestation for a rodent!
The porcupine cub, a “porcupette”, at birth, weighs more than newborn grizzly bear cubs!
Pups, are usually born in late April to early May, but could arrive as late as August. When the infant is born, its eyes are open, teeth erupted & its quills are soft. (Sure would be a real prickly venture for mom for sure otherwiseJ Quills will harden in an hour or so after birth. The baby will begin to forage foods within days after birth, but mom will continue to nurse the baby until it is approximately 3.5mos old. The baby will stay with its mother until it is about 6mos old. Color darkens with age. They reach adult size in 3-4 years.
A sample growth size I found of porcupine pups could be as follows:
Birth weight 0.45kg
15 days 0.85kg
3mos 1.85kg
4mos 2.15kg
Juvenile survival rates are high.
It is said that porcupettes are denned on the ground & the mother will care for them when they come down from the trees.
Females reach sexual maturity at about 12-18mos old. Males reach sexual maturity at about 24mos of age, although some ranges do exist.
Female porcupines have 4 nipples.
Territory & Habitats
Porcupines are spread throughout most of North America, even down through the Northern part of
In the
Porcupines will usually choose different trees for feeding & for resting.
In the east, they often choose hemlocks over conifers for resting, & for feeding. Hemlocks may be preferred because of their thick foliage. The thick foliage helps the porcupine to stay warm & hidden. Hemlocks are sturdy & also provide high nutritional value to the porcupine.
In the southwest of
Porcupines in the
Porcupines of the Great Basins will use dens in rocks. They will use juniper trees for cover in winter. Porcupines of the Great Basins will often travel between dens & areas near rivers to forage on tree barks. Traveling around in this manner makes them prone to predator attacks.
Prickly Problems
The fisher was introduced to some areas of
However, the porcupine is actually VERY beneficial to our ecosystem. It would be a great loss to our World to lose our great little prickly pal.
A study on red spruce in
Another reason they are considered pests, is they like to come into camps & they will gnaw on buildings. They are not doing this to upset us, but just probably happened to like the wood we chose! Remember they need to continually chew to trim their teeth. There are humane ways to deter porcupines, please try those before shooting, trapping or poisoning them!! Not all the things that the porcupines eat are upsetting to people! They also eat mistletoe, which is a parasite on trees. It is a favored food of porcupines! The porcupines’ habits of eating in the dense populations of saplings & killing weed trees are considered good forestry practices.
Porcupine Control
Most of the damage caused by porcupines is in the winter season. In the winter, the woody plants become a staple of the porcupine’s diet. Evidence of porcupine attacks are the extensive gnawing of branches, twigs & bark. Vulnerable trees include the pine, spruce, poplar, elm, fruit-producing trees & many varieties of shrubs. If the porcupine should happen to eat the bark all the way around the tree, extensively, it will kill the tree. (This is called “girdling”).
During the summer, porcupines may damage fruits, vegetables or succulent plants.
Porcupines may chew on beams or supports structures of wooden buildings – man-made structures.
Dogs seem to have a considerable problem with porcupines – as they just don’t seem to learn to stay away from them! They often end up with a muzzle full of quills!
Most plant damage can be stopped by removing the porcupine(s). Other porcupines from the surrounding areas are not usually too quick to move into the area, so this makes removal of the animal(s) an effective prevention & control technique.
******** PLEASE BE SURE TO CHECK WITH YOUR LOCAL AREA LAW (DEC or DEP) ON PORCUPINE CONTROL LEGALITY!
Exclusion Techniques
Porcupines climb very well, making it very difficult to put up barriers to keep them out.
Individual trees can be protected though. Place a band 30 inches (76cm) of sheet metal, or, aluminum flashing at the base of each tree.
(pictures by 3 of my kids)
Electric fencing, if legal in your area for the use of, can be used to keep porcupine out. Enclose the area you wish to keep them out of with 60cm high poultry wire & then tightly stretch the wire over the posts set 6 to 8m apart. Make certain the bottom of the wire mesh is at or below ground level, or the porcupine may find a place to squeeze under.
Next, put a 12.5 gauge smooth high-tensile wire around the outside fence perimeter, 45cm above the ground, using insulators at every post. The smooth wire must be kept no more then 4 cm away from the poultry wire. If the distance is greater, the porcupine will squeeze between the 2 wires, without receiving an adequate shock.
Increase height of poultry mesh & charged wire during winter to account for snow depth.
My Experiences:
So far, I have yet to see one of these beauties in the wild, alive, I am sad to say. Their slow moving nature makes the a victim to automobiles frequently & in the last 4 yrs, the only 2 I have seen were dead on the side of the road. The first one I saw was in Spring 2005, I believe. I had wished I had at least stopped to take photos, because up till that point I had not seen a NA porcupine, except photos on the net! So, all I had was a brief look going by in the car. I regretted not stopping to look. Then the other was just yesterday. (Sunday, August 6th, 2006). I saw it on the way to my mother’s & thought about it the whole time I was there. I was nervous to stop. I knew someone would think I had lost my mind! But I didn’t care either! How else am I supposed to learn about them??? I don’t recommend anyone to just stop though because those quills are OUCHY! LOL So, after leaving mom’s I went back to porcupine, which was then on the opposite side of me, so I had to go around a loop & come back. I stopped & took several photos & looked at quills laying on the ground & decided it was a car accident victim for sure, poor thing. Of course, right there like that I couldn’t be 100% sure, but I was pretty sure. I got some bags (which are NOT good things to bring porcupines home in!) & scooped “him” up & brought him home! Which was not “just” that easy! LOL An officer stopped, & looked at me like I was insane. I explained about taking photos & how I wanted to take the porcupine home & I also showed him my rehabilitator’s license! LOL
Here are things I learned & documented on my porcupine:
Porcupine was a female.
She was about 26” long from nose to rump – making her an adult.
She was about 11” tall, paw to shoulder.
She was about 4” nose to ear (angle).
(I LOVE the paw pads!)
Her front paw pads were about 1 & ½” long, with claws ranging 1 – 1 ½”.
She had 4 claws on each of her front paws.
Her back paw pads were about 2 & ½” long with claws ¾” – 1 & ½”.
She had 5 claws on her back paws.
Her back legs were about 3” long – her front legs were harder to measure, so I didn’t get that.
She had an 8” tail.
Her 4 front teeth (the gnawing teeth - incisors) – were approximately ½” long. The top 2 were broken – the protective coating was broke of them.
She had a cut to the right side of her abdomen that wasn’t too bad, some blood from her little nose, a laceration on her front leg. So she must have sustained some major internal injury, as the outside wasn’t bad. Poor “little” girl.
We estimated her weight to be approximately 10-13lbs, since she had begun bloating, it was harder to get an accurate weight & I don’t have a scale that big (for her) – yet!! So we winged it by hand.
References, Resources, Credits, Tributes:
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Husbandry Standards for Keeping Porcupines in Captivity by Christine Bartos, Baltimore Zoo, Druid Hill Park, Baltimore MD (I used this for a lot of information I needed personally, but it also helped for researching the nutrition,etc).
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Minimum Standards for Wildlife Rehabilitation, 2000, IWRC & NWRA
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Control of Porcupine Damage – Revised July 2005 agdex684-11 – 684-11.pdf
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Animal Tracks – Porcupine
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Porcupines – ro_b81.pdf
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Getting to Know Nature’s Children Porcupines c.1985 by Grolier
These photos are ones I took & © by me. I put all this together, from months of research. I used websites & books & have listed my resources. They are awesome websites & should be visited.
Last Edited on: Sunday, August 13th, 2006 10:05am