PORCUPINE

PORCUPINE

Physical Characteristics

The so-called "Big Five" group of animals includes the elephant, rhino, buffalo, lion and leopard. Some years back a scientist suggested a "Small Five" group of animals, consisting of the aardvark, ratel, porcupine, pangolin and the naked mole-rat. Although at first this may seem a humorous suggestion, it is a reminder that many other interesting, lesser-known animals exist.

The crested porcupine is the largest and heaviest of African rodents. The head is roundish and rather domed, with a blunt muzzle and small eyes and ears. The legs are short and sturdy, and each foot has five toes, all equipped with powerful claws.

The porcupine is, of course, easily recognized by its most notable feature—its quills. Quill length on different parts of the body varies, from 1 inch up to 12 inches on the back. Usually the quills lie flat against the body, but if danger threatens, the porcupine raises and spreads them. Scales on quill tips lodge in the skin like fishhooks and are difficult to pull out. New quills grow in to replace lost ones.

Habitat

Porcupines are most common in hilly, rocky country, but they can adapt to most habitats. Excessively moist forests and the most barren of deserts seem to be the only exceptions. They have even been found on Mt. Kilimanjaro, as high up as 11,480 feet.

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Behavior

Natural shelters among roots and rocks are modified by porcupines to suit their needs. They will inhabit holes made by other animals but also dig their own. These burrows are most commonly occupied in family units.

The porcupine warns potential enemies of its defense system when alarmed. It will stamp its feet, click its teeth and growl or hiss while vibrating specialized quills that produce a characteristic rattle. If an enemy persists, the porcupine runs backward until it rams its attacker. The reverse charge is most effective because the hindquarters are the most heavily armed and the quills are directed to the rear.

Not much is known about the breeding habits of porcupines in the wild, but the gestation period of the African crested is about 112 days. Between one and four young are born in a grass-lined burrow. They are well-developed and have their eyes open at birth. The young leave home for the first time at about 2 weeks of age as their quills, soft at birth, begin to harden. They are quite playful and, outside the burrow, they run and chase one another. The young are suckled for 6 to 8 weeks, when they begin to eat vegetable matter. Porcupines readily adapt to captivity and become quite tame, some living as long as 20 years.

When porcupine populations close to cultivated areas surge, they can become serious agricultural pests. They are smoked out of their burrows and hunted with spears, nets or dogs, practices that have eliminated them from densely settled areas.

Diet

Porcupines primarily eat roots, tubers, bark and fallen fruit but have a fondness, too, for cultivated root crops such as cassava, potatoes and carrots. Sometimes porcupines will take carrion back to the burrow to nibble on.

Predators and Threats

Especially in heavily settled areas, porcupines can be serious agricultural threats and porcupines can do a lot of crop damage in a single night. They are hunted using dogs, spears or nets, or smoked out of their burrows.

Did You Know?

The word porcupine means "quill pig" in Latin; however, porcupines are large rodents and not related to pigs at all.

Porcupine quills have long been a favorite ornament and good-luck charm in Africa. The hollow rattle quills serve as musical instruments and were once used as containers for gold dust.

This animal

•       is believed to have over 30 000 quills

•       lashes its tail threateningly when disturbed, possibly detaching loose quills, which fly through the air as though they were thrown

•       chews on a variety of objects, including wood, leather, bones, and cast-off antlers, perhaps to satisfy a craving for salt and the need to hone continuously growing teeth

•       is a solitary animal for much of the year

Description   

The porcupine Erethizon dorsatum is one of Canada’s best-known mammals, both in life and in legend. Its fame stems from its coat of quills, which keeps most enemies at a respectful distance.

When sitting hunched high up in a tree, a porcupine could be mistaken for the nest of a squirrel or a crow, but close to the ground it is easily recognized. It has a short, blunt-nosed face with small eyes. The ears are small and round, almost concealed by the hair, which also covers the spines. The shoulders are humped, making the back look arched. The short legs are bowed, and the animal stands bear-like with its entire foot planted firmly on the ground. The claws are long and curved. On the hind feet the first digit is replaced by a broad movable pad that allows the animal to grasp branches more firmly when climbing. The muscular tail is thick, short, and rounded at the tip.

The porcupine’s coat consists of a soft, brown, woolly undercoat and coarse, long guard hairs. At the base, each guard hair is brown, becoming darker near the tip, which may be white in eastern populations and yellow in the western ones. The guard hairs conceal the quills until the porcupine is aroused. The quills are longest on the back and tail and when raised push the guard hairs forward, forming a crest. On the face the quills are about 1.2 cm long; on the back they may be up to 12.5 cm in length. There are no quills on the muzzle, legs, or underparts of the body.

Each quill is hollow and embedded in the skin, where it is attached to a small muscle that pulls it upright in the fur when the animal bristles with alarm. About 0.6 cm from the tip, the quill tapers to a fine point closely covered by several dozen small black barbs. These barbs feel only slightly rough to the touch, but when they are moist—as when embedded in flesh—they swell, working the quill farther in. The quills have black tips and yellow or white shafts.

It has been estimated that the porcupine has over 30 000 quills, so it is not incapacitated by a single encounter with an enemy, when several hundred quills may be dislodged. As the quills are lost they are replaced by new ones, which are white and sharp and which remain firmly anchored in the skin until they are fully grown.

The porcupine is Canada’s second largest rodent, next to the beaver. Adult males reach an average weight of 5.5 kg after six years; the females reach 4.5 kg. The total length averages 68 to 100 cm, and the height at the shoulders is about 30 cm.

Signs and sounds

When in a den or up a tree, a porcupine is not always easy to see, but noisy chewing, cut twigs, and missing patches of bark may advertise its presence. Around feeding trees and especially outside the winter dens, scats, or droppings, are often visible. In the winter, these are rough and irregular in shape; in summer they tend to be rounded and soft turning from greenish brown to dark brown as they age.

In winter, the tracks can be recognized by the firm print of the whole sole placed heavily on the ground, the long claw marks, and, sometimes, marks where the tail has dragged. If the snow is soft and deep, the porcupine trail becomes more of a trough through the snow.

In fall, and to a lesser extent at other times of the year, porcupines may be called by a low puppylike whine repeated up and down the scale.

During confrontations, a porcupine will chatter its teeth. Otherwise porcupines are mainly uncommunicative animals. The female may nose her young with subdued grunts and whines. Only in the mating season do porcupines become noisy, creating a variety of moans, screams, grunts, and barks.

Habitat and habits         

Although the species of porcupine found in North America always lives among trees, it does not always live in mature forests and may be found in alder thickets along rivers and in dwarfed pine scrub along ridge crests. It is most common where there are rocky ledges and rock piles suitable for dens and stands of aspen, hemlock, and other trees.

Being shortsighted and slow moving, the porcupine is not too difficult to approach once found.

The defensive behaviour of the porcupine is well known though sometimes misinterpreted. If on the ground when danger threatens, the porcupine will make for the nearest shelter, under a rock or log or up a tree, even forsaking its slow walk for a clumsy gallop. If thwarted in such a retreat, it will hump its back, tucking its unprotected head between its shoulders. With all the quills erected, the porcupine will pivot on its front feet and keep its back to the enemy. As it stomps its back feet, it also lashes its tail threateningly. The momentum of the tail may detach loose quills, which fly through the air, giving the impression that they were thrown.

When caught in a trap, a porcupine may, in its struggles, embed its own quills in itself. It removes these quills—or foreign quills from another porcupine—with considerable dexterity using teeth and front paws.

A treed porcupine will survey danger with an air of unconcern, but should the enemy start to climb the tree, the porcupine will back down flicking and lashing its tail.

For much of the year the porcupine enjoys no social life and leads a solitary existence. Porcupines group together for winter denning or food rather than social reasons. Several porcupines may gather around a favoured food, and up to a hundred have been found in large rock piles in winter. At these times they are usually tolerant and ignore each other totally, although there may be some teeth chattering over food. Young porcupines are often playful and shadowbox using their tails. Sometimes even the normally rather sedate adults are known to play.

During winter the porcupine does not hibernate. However, it does not usually move far and feeds within 100 m of its den. During snow or rain it will remain in the den or, if outside feeding, will sit hunched in a tree, even during subzero weather, until the rain or snow stops. When the weather is dry in winter it will feed at any time of the day or night, but during the rest of the year it is nocturnal despite the weather. In summer the porcupine ranges farther from the den, often searching for food up to 1.5 km away. As well as these daily movements within the home range, there may be seasonal movements between winter denning areas and the summer feeding areas. In mountainous country, the porcupines will often descend during the winter along well-defined routes marked by debarked trees. In the spring, they return up the mountainside to summer feeding areas.

Unique characteristics

Aboriginal people dye porcupine quills and use them in decorative work. Before the Aboriginal people moved to reservations they ate a lot of porcupine meat, especially in winter, and later they hunted the porcupine’s worst enemy, the fisher, for its fur.

Range          

The porcupine occurs in North America in a wide range of vegetation types from semi-desert to tundra. Porcupines also occur in Africa and Asia, but Old World porcupines do not belong to the same family as New World porcupines.

Feeding        

The porcupine feeds largely on the inner bark of trees in winter, but it will also feed on a variety of other plants. During winter, although the needles and bark of most trees are acceptable, there are clear favorites: yellow pine in the west, white pine in the Great Lakes area, and hemlock in the northeast states. When the sap rises in spring, the bark of maples is favoured along with the catkins and leaves of alder, poplar, and willow. As more plants come into leaf, the porcupine will eat the leaves of herbs and shrubs, such as currant, rose, thorn apple, violets, dandelion, clover, and grasses. Particularly sought after are the succulent leaves of water lily and arrowhead, for which the porcupine will wade out into streams and even swim, its air-filled quills helping it to keep afloat. In the fall, it will eat beechmasts, or beech tree nuts, and acorns and is not averse to raiding cornfields and orchards.

One of the porcupine’s best-known and least-liked eating habits is that of chewing wood and leather in and about camps. It gnaws both salty and non-salty objects, which indicates the habit may stem not only from a craving for salt, but also from a need to hone the continuously growing teeth. When human-made objects are not available, the porcupine will chew bones and cast-off antlers.

The porcupine is a slow and deliberate feeder, relying on its nose rather than its eyes to guide its selection of plants. This has sometimes led people to believe that porcupines are stupid. However, porcupines are said to have good memories and to be intelligent animals that are capable of learning quickly.

Breeding    

Porcupines first breed when they are one or two years old. In the southern part of their range they mate in September, but in the more northerly latitudes, in late October to November. The male will follow the female during this period and serenade her with grunts and humming. The female is in heat, or sexually receptive, for only eight to 12 hours and frequently initiates courtship. When she is ready to mate, she indulges in a kind of dance with the chosen male, where they both rise on their hind feet to embrace, all the while whining and grunting. Sometimes they place their paws on each other’s shoulders and rub their noses together; then they may cuff each other affectionately on the head and finally push one another to the ground. Mating used to be the subject of considerable speculation and ingenious theories, but the explanation is simple. The female flattens her quills and twists her tail out of the male’s way so he can mount in the normal fashion. Mating finishes abruptly and either one of the partners then climbs a tree and screams at the other if further approaches are made.

The gestation, or pregnancy, is about 30 weeks; birth occurs sometime between March and May depending how far north the porcupine is located. The female makes almost no preparations for the birth and does not seek out a nesting den or bed. The solitary baby (twins are almost unknown) may be born in a rock pile, under a log stump, or under a brush pile.

The baby porcupine is well developed at birth: its eyes are open, and the blunt incisor teeth and molars are already exposed. About 30 cm long, it weighs approximately 0.4 kg and is covered in dense black hair. The sharp barbless quills are soft and concealed in the hair. Within hours of birth the quills harden and can be erected. After a couple of days, the baby porcupine can climb, although it tends to spend more time on the ground. After a week or so, the female leaves the baby for longer and longer periods while she feeds on the emerging green plants. Weaning, or making the transition from mother’s milk to other food, takes seven to 10 days, although in captivity it may take longer. By the fall, most young porcupines live apart from their mothers.

Conservation        

Being slow moving, the porcupine is a frequent victim in forest fires and on roadways. Injuries from climbing are not uncommon, and diseases, especially rabbit fever, take their toll. External parasites, such as ticks and lice, and internal parasites, round worms, tape worms, and thread worms, are plentiful, although they apparently have no ill effects on the porcupine.

Porcupine quills have been found embedded in several predators, including the coyote, cougar, bobcat, red fox, lynx, bear, wolf, fisher, and Great Horned Owl. Some more experienced predators learn to avoid the quills and kill the porcupine by biting its head or by flipping the porcupine onto its back to expose the unprotected belly. The fisher is the best-known porcupine hunter. It was successfully introduced into some areas of New England to reduce porcupine populations.

European colonists caused a decrease in the fishers, by trapping them and deforesting the southern part of their range. The consequent increase in the number of porcupines coupled with the fact that porcupines damage and even kill some trees led to their being branded as pests. However, a study in a red spruce area in Maine, with 20 to 28 porcupines per 2.5 km2, showed the loss of trees was only 0.5 percent. They are also considered to be pests because of their habit of gnawing buildings around camps. In areas where porcupines are a problem, they are shot, trapped, or poisoned using salt baits. However, not all that the porcupine eats is upsetting to humans. For example, mistletoe, a parasite on trees, is a favoured food. Also the porcupine’s habits of thinning out dense stands of saplings and of killing weed trees are considered to be good forestry practices