North American porcupine

Appearance

Porcupines are usually dark brown or black in color, with white highlights. They have a chunky 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, not counting a tail of 14.5 to 30 cm.

The hindfoot length is 7.5 to 9.1 cm. Weight can range from 3.5 to 18 kg, although they average under 9 kg.

Naming

The word ''porcupine'' comes from the middle or old French word ''porcespin'', which means spiny pig. Its roots derive from the Latin words "porcus" or pig and "spina" meaning thorns.

Behavior

Porcupines are nearsighted and slow-moving.

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.

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.

Reproduction

Porcupines breed in the fall and the young porcupine is born in the spring, with soft quills that harden within a few hours after birth. When porcupines are mating, they tighten their skin and hold their quills flat, so as not to injure each other.

Food

Porcupines are mainly active at night; 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.

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".

Predators

Natural predators of this species include fishers, 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. Due to its dangerous quills, the North American porcupine is often avoided as prey and even their largest predators have been known to be harmed or killed by their quills.

Most predators of the porcupine will attempt to stun or cause massive blood loss with an attack to the face and then will spin them over to their unprotected underside. The porcupine can embed several painful quills directly into a predator's body, which may save their own lives.

Defense

Their upper parts are covered with thousands of sharp, barbed hollow spines or quills, which are used for defense. Porcupines do not throw their quills, but the quills detach easily and the barbs make them very difficult to remove once lodged in an attacker. The quills are normally flattened against the body unless the animal is disturbed. The porcupine also swings its quilled tail towards a perceived threat.

Evolution

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 is 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.

The earliest appearance of ''Erethizon dorsatum'' is from the Pleistocene era found along the Arroyo del Cedazo near Aguascalientes, Mexico.