North American porcupine
|North American porcupine
Temporal range: Pleistocene - Recent
F. Cuvier, 1823
The North American porcupine (Erethizon dorsatum), also known as the Canadian porcupine or common porcupine, is a large rodent in the New World porcupine family. The beaver is the only larger rodent in North America. The porcupine is a caviomorph rodent whose ancestors rafted across the Atlantic from Africa to Brazil over 30 million years ago, and then migrated to North America during the Great American Interchange after the Isthmus of Panama rose 3 million years ago.
They range from Canada, Alaska, and into northern Mexico. They are commonly found in coniferous and mixed forested areas but have adapted to harsh environments such as shrublands, tundra and deserts. They make their dens in hollow trees or in rocky areas.
The word porcupine comes from the middle or old French word porcespin, which means quill pig. Its roots derive from the Latin words "porcus" or pig and "spina" meaning thorns. Other colloquial names for the animal include quill pig. It is also referred to as the Canadian porcupine or common porcupine. The porcupine's genus species name, Erethizon dorsatum can be loosely translated as "the animal with the irritating back." There are several native American names such as the Lakota name pahin meaning quill and the Chipewyan name ts'l.
The North American porcupine is descended from South America where all new world porcupines or hystricomorphs evolved. Erethizon appeared in North America shortly after the two continents joined together in the later Tertiary period. Other hystricomorphs also migrated but Erethizon was the only one to survive north of Mexico. There are no known fossils attributed to hystricomorphs prior to the late Tertiary period. Some fossils such as species from the family Paramyidae show resemblance to the porcupine but they are so primitive and generalized that they could be ancestors to all later rodents.
South American hystricomorphs first appeared in the Lower Oligocene period. It is thought they migrated from Africa, ancestors of the old world porcupines or Hystricidae or they originated based on a migration of the North American Paramyidae.
Seven subspecies of Erethizon dorsatum are recognized. They are subdivided by different ranges across North America. By far the most common is E. d. dorsatum, which ranges from Nova Scotia to Alberta and from Virginia to the Yukon. E. d. picinum occupies a small range in northeastern Quebec and Labrador. E. d. couesi is the most southern ranging from northern Mexico to Colorado. E. d. bruneri can be found in the midwest from Arkansas to Montana. The last three are western species. From south to north they are E.d. epixanthum, E. d. nigrescens, and E. d. myops.
Porcupines are usually dark brown or black in color, with white highlights. They have a stocky body, a small face, short legs, and a short thick tail. This species is the largest of the New World porcupines and is one of the largest North American rodents, second only to the American beaver in size. The head-and-body length is 60 to 90 cm (2.0 to 3.0 ft), not counting a tail of 14.5 to 30 cm (5.7 to 11.8 in). The hindfoot length is 7.5 to 9.1 cm (3.0 to 3.6 in). Weight can range from 3.5 to 18 kg (7.7 to 39.7 lb), although they average about 9 kg (20 lb).
The porcupine is the only native North American mammal with antibiotics in its skin. Those antibiotics prevent infection when a porcupine falls out of a tree and is stuck with its own quills upon hitting the ground. Porcupines fall out of trees fairly often because they are highly tempted by the tender buds and twigs at the ends of the branches. The porcupine, wolverine, and the skunk are the only North American mammals that have black and white colours because they are the only mammals that benefit from letting other animals know where and who they are in the dark of the night.
Ths most distinguishing feature of the porcupine is its coat of quills. An adult porcupine has about 30,000 quills that covers all of its body except its underbelly, face and feet. Quills are modified hairs that are sharp, barbed hollow spines. They are used primarily for defence but also serve to insulate the body during winter. Porcupines do not throw their quills, but when threatened the porcupine contracts the muscles near its skin which caused the quills to stand up and out from its body. When the quills are in this position they become easier to detach from its body, especially when the porcupine swings its tail towards an attacker. The barbs at the tip become lodged in the flesh of an attacker and are difficult and painful to remove. The quills are normally flattened against the body and in this position are less easily dislodged.
Porcupines are selective in their eating; out of 1000 trees in the Catskill forest, one or two are acceptable lindens, and one is a bigtooth aspen. Consequently, the porcupine has "an extraordinary ability to learn complex mazes and to remember them as much as a hundred days afterward".
Porcupines are nearsighted and slow-moving. Porcupines are mainly active at night (nocturnal); on summer days, they often rest in trees. During the summer, they eat twigs, roots, stems, berries, and other vegetation. In the winter, they mainly eat conifer needles and tree bark. They do not hibernate but sleep a lot and stay close to their dens in winter. The strength of the porcupine's defense has given it the ability to live a solitary life, unlike many herbivores, which must move in flocks or herds.
The North American porcupine has a number of warning and defensive behaviours to warn or deter predators. Its first line of defence lies in the coloration of its quills. When threatened, an adult porcupine can bristle its quills showing a white stripe down its back. Its second line of defence uses its teeth to make a warning clacking sound. A third method is that it can emit a strong pungent odor by secreting a scent mixed with its urine. If the visual, auditory, and olfactory warnings fail then it can rely on its quills. An adult porcupine when attacked will turn its rear to face a predator. When approached the porcupine can swing its tail at an attacker's face. Despite popular myth, the porcupine does not throw its quills. Instead when they come in contact with the attacker surface they can easily penetrate and become embedded in its skin. Each quill contains microscopic barbs which allow them to stick into the flesh of an attacker. This strategy is successful against most attacks. With a face full of quills which can be very painful an attacking creature often retreats. Its last line of defence is to climb a tree which provides protection from most predators.
Natural predators of this species include fishers (a cat-sized marten), wolverines, coyotes, wolves, bears, and cougars as well as humans. The only known avian predators of this species are golden eagles and great horned owls.
The North American porcupine is most at risk (other than humans) to the fisher (Martes pennanti). Fishers are related to the weasel and weigh up to 5.5 kg. Fishers have two advantages that make it a capable hunter of the porcupine. First they are agile tree climbers. If a fisher locates a porcupine it cannot hide by fleeing into a tree because the fisher can pursue it and force it down to the ground. Porcupines can sometimes defend themselves by facing the trunk on a branch and presenting their tail to the fisher. If the fisher manages to force a porcupine down to the ground, the porcupine will try to present its hind quarters and tail to the attacker but fishers are quick and agile. As it circles the porcupine, every chance it gets it bites the face. After repeated attacks the porcupine eventually weakens allowing the fisher to bite the porcupine's underbelly thus killing it. Fishers will then consume the porcupine through the chest and abdomen avoiding the quills. One study suggested that since male fishers are larger than females it is likely that only males will hunt porcupines.
Another effective predator is the mountain lion. It does not bother with quill avoidance but tolerates them. Some individuals have been found with dozens of quills embedded in their gums to no ill-effect. It can climb trees so its favorite method is to position itself below the porcupine and knock it to the ground where it is quickly dispatched. Other predators can attack such as wolves, lynx, and great horned owls but do not pose much of a threat.
Female porcupines are solitary for most of the year except during the fall when breeding season begins. At this time they secrete a thick mucus which mixes with their urine. The resulting odor attracts males in the vicinity. Males that approach a female do not automatically begin mating. The first male that comes along will typically sit in the same tree below a female. If another male approaches he may fight for the right to mate. Once a dominant male is successful it will approach the female and use a spray of its urine on the female. Only a few drops touch the female but the chemical reaction allows the female to fully enter estrus. Once this is accomplished high in the tree, the mating process takes place on the ground. When porcupines are mating, they tighten their skin and hold their quills flat, so as not to injure each other. Mating may occur repeatedly until the female loses interest and climbs back in to the tree.
The North American porcupine has a long gestation period relative to other rodents. The female porcupine's pregnancy lasts for 202 days. By contrast the North American beaver which is comparable in size has a gestation period of 128 days. The eastern grey squirrel (Sciurus carolinensis) has a gestation period of just 44 days. Porcupines give birth to a single baby. Baby porcupines are called a porcupette. At birth they weigh about 450 grams which increases to nearly 1 kg after the first two weeks. They do not gain full adult weight until the end of the second summer at about 4.5 kg. Their quills harden soon after birth.
Female porcupines provide all the maternal care. For the first two weeks, porcupettes rely on their mother for sustenance. After this they learn to climb trees and starts to forage. Porcupettes will continue to nurse for up to four months which coincides with the fall mating season. They stay close to their mother. Mother porcupines will not defend their young but have been known to care for them even after death. In one case when a baby had fallen to his death from a tree, the mother came down and stayed by her baby's side for hours waiting vainly for the baby to revive.
North American porcupines have a relatively long life expectancy. Some individuals have been found to live up to 25 to 30 years of age. Common causes of mortality include predation and starvation. Porcupines can also die from falling out of a tree and are they are also killed by motor vehicles.
Porcupines and humans
They are considered by some to be a pest because of the damage that they often inflict on trees and wooden and leather objects. Plywood is especially vulnerable because of the salts added during manufacture. The quills are used by Native Americans to decorate articles such as baskets and clothing. Porcupines are edible and were an important source of food, especially in winter, to the Natives of Canada's boreal forests. They move slowly (having few threats in its natural environment which would give it the need to flee quickly) and are often hit by vehicles while crossing roads.
Globally the North American porcupine is listed as a species of least concern. It is common throughout its range except in some U.S. states in the southeast part of its range. For example, it is listed as a species in need of conservation in Maryland. As of 1999, 15 remnant populations remain scattered throughout north central Mexico. They live in riparian forests, mesquite scrubland, grasslands and thorn forests. They are threatened by hunting and habitat loss. As of 1994, it was listed as an endangered species in Mexico.
Bark of Sugar Maple eaten by a porcupine
- ITIS claims that Erethizon dorsatus is a valid name while Erethizon dorsatum is invalid, assuming that Erethizon is a masculine Latin noun; however it is in fact a Greek participle, not a Latin noun.
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