Female cougars have no fixed breeding season. They are polyestrous, being receptive to mating several times during the year, but they normally have only one litter every other year. The loudest vocalization of the cougar is heard during this time, advertising a female's readiness to mate. Most kittens are born in the first half of the year, after a gestation period of about 3 months. Average litter size is three kittens.
Mortality rate is high, often with only one kitten surviving to join the adult breeding population.
Cougars live to be about 10 or 12 years of age in the wild. The cougar's primary food animals are deer and elk. Other hoofed animals, beavers, hares, and small rodents can be part of the diet. Very young, unskilled lions and very old or injured individuals tend to be more opportunistic, eating whatever they can actually get their paws on. Cougars also frequently learn to eat porcupines, mostly managing to avoid the quills.