Females go into season by the age of three, and have cubs about every two years. Males detect when the female is entering estrous by smelling the females urine. Before mating, the lion will roll on her back and make various other movements accompanied by a low moan. When she has gotten the male's attention, she crouches into the mating position, and Copulation occurs for five to twenty seconds. They may continue this every half hour for up to a week. After a gestation period of 105 days, two to four cubs are born blind and helpless in a shelter away from the pride. After a little over a month, the cubs are introduced to the pride. Before they reach the age of three to four months, the cubs depend on not only their mother's milk but any other nursing lionesses in the pride. They begin to join their mother in hunts after about three to four months, and begin to kill on their own after about two years.