While the porcupine does not throw quills, the flailing muscular tail and powerful body may help impel quills deeply into attackers. The quills' barbed ends expand with moisture and continue to work deeper into flesh. Porcupine quills have mildly antibiotic properties and thus are not infectious. Quills may cause death if they puncture a vital organ or if a muzzle full of quills leads to starvation. Males fiercely compete for breeding rights.
Courtship consists of a period of wrestling, chases, vocalizations and urine showers.
A receptive female folds her quills flat against her body, elevates her rear and arches her tail over her back. This provides the male with a quill-less platform. Mating continues until one of the pair ends contact by climbing a tree or hostile screaming. A Mostly Quiet Life Porcupines are generally solitary in nature, although groups up to a dozen may gather at certain nocturnal feeding sites during summer and early autumn. Numerous porcupines may share a den on a rotating basis, and several may share a winter den at the same time.