Porcupine Gestation Cycle

Mating season typically occurs in the fall, usually October and November. Females choose a small territory and defend it from other females. Males also choose territories, but theirs overlap each other's and might cover several female territories. Males start to show more aggression than normal, fighting rather violently to prove dominance and to encourage the females to make a decision on a mate. The males vocalize loudly, bite each other and try to stab each other with quills.

Female porcupines have short estrous periods, usually about eight to 12 hours. To make sure they have males waiting when the time is right, females start advertising their breeding readiness one to four days prior to ovulation with high-pitched noises, urine marking and vaginal secretions. In a rather odd courting ritual, males spray urine on the female. If she moves away, she's not interested. If she withstands the urine shower, she's receptive to the male. He then stays with her and helps defend her territory until she's ready to mate.

When a female is ready to mate, she and her chosen male leave the trees and head for the ground. It takes several hours for porcupines complete their copulation. It typically continues until the male is forced to stop by the formation of a vaginal plug in the female. This plug also ensures she can't mate with other males.

After mating, females are pregnant for about seven months -- usually between 205 and 217 days. Instead of having a litter of several small babies like many mammals do, porcupines have one large baby. A baby weighs about a pound, typically ranging from 14 to 18 ounces. Their quills are soft when they're born, but the quills harden within an hour. Mother porcupines nurse their babies for about four months, although the babies stay with their mothers for another month or two before setting off on their own.