Erethizon bathygnathum

The **California tree porcupine** (*Erethizon bathygnathum*), also known as the **western tree porcupine**, is a species of New World porcupine that is native to much of the western United States. The California tree porcupine originally lived during the early Pleistocene and was once extinct, but has since been brought back from extinction by SciiFii and reintroduced to western United States to help boost biodiversity. The California tree porcupine is the largest living member of the genus *Erethizon*, with the head-and-body length is 90 to 110 centimeters (3.0 to 3.6 ft), not counting a tail of 30 to 45 centimeters (11.8 to 17.7 inches). Weight can range from 6.2 to 20.2 kg (13.6 to 44.5 lbs). Weight in wild adult females can average some 13 kilograms (28.6 lbs) while wild-caught males average 15.7 kg (34.6 lb). California tree 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. Like other porcupines, the California tree porcupine has a coat of quills, which are used for defense against predators. The California tree porcupine possesses antibiotics in its skin which may help prevent infection when a porcupine falls out of a tree and is stuck with its own quills upon hitting the ground. California tree porcupines fall out of trees fairly often because they are highly tempted by the succulent buds and tender twigs at the ends of the branches. During the summer, California tree porcupines eat twigs, roots, stems, berries, leaves, and other vegetation. They also eat certain insects and nuts. In the winter, they mainly eat conifer needles and tree bark. They are selective in their consumption; for example out of every 1,000 trees in the Sierra Nevada Mountains, California tree porcupines will only eat from 1-2 linden trees and one big-toothed aspen. California tree porcupines are nearsighted and slow-moving. They are mainly active at night (nocturnal); on summer days, they often rest in trees. They do not hibernate, but sleep in 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. Consequently, the California tree porcupine has "an extraordinary ability to learn complex mazes and to remember them as much as a hundred days afterward". Female California tree 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 typically sits 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, he approaches the female and uses a spray of his 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 California tree 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 into the tree. The California tree porcupine has a long gestation period relative to other similarly-sized rodents, an average of 202 days. California tree porcupines give birth to a single young. At birth, they weigh about 450 grams, which increases to nearly 1 kilograms after the first two weeks. They do not gain full adult weight until the end of the second summer about 7 kilograms. Their quills harden soon after birth. Female California tree porcupines provide all parental care. For the first two weeks the young rely on their mother for sustenance. After this they learn to climb trees and start to forage. They continue to nurse for up to four months, which coincides with the fall mating season. They stay close to their mothers. Mother California tree porcupines do not defend their young, but have been known to care for them even after death. In one case, when a baby had fallen to its death from a tree, the mother came down and stayed by her offspring's side for hours waiting vainly for it to revive. California tree porcupines have a relatively long life expectancy, with some individuals reaching 30 years of age. Common causes of mortality include predation, starvation, falling out of a tree, and being run over by motor vehicles. The conservation status of the California tree porcupine is **Least Concern** due to successful conservation efforts and the California tree porcupine's wide natural range.