of the neck. Usually, the mother does not integrate herself and her cubs back into the pride until the cubs are six to eight weeks old. Sometimes the introduction to pride life occurs earlier, particularly if other lionesses have given birth at about the same time. When first introduced to the rest of the pride, lion cubs lack confidence when confronted with adults other than their mother. They soon begin to immerse themselves in the pride life, however, playing among themselves or attempting to initiate play with the adults. Lionesses with cubs of their own are more likely to be tolerant of another lioness's cubs than lionesses without cubs. Male tolerance of the cubs varies—one male could patiently let the cubs play with his tail or his mane, while another may snarl and bat the cubs away. Pride lionesses often synchronise their reproductive cycles and communal rearing and suckling of the young, which suckle indiscriminately from any or all of the nursing females in the pride. The synchronisation of births is advantageous because the cubs grow to being roughly the same size and have an equal chance of survival, and sucklings are not dominated by older cubs. Weaning occurs after six or seven months. Male lions reach maturity at about three years of age and at four to five years are capable of challenging and displacing adult males associated with another pride. They begin to age and weaken at between 10 and 15 years of age at the latest. When one or more new males oust the previous males associated with a pride, the victors often kill any existing young cubs, perhaps because females do not become fertile and receptive until their cubs mature or die. Females often fiercely defend their cubs from a usurping male but are rarely successful unless a group of three or four mothers within a pride join forces against the male. Cubs also die from starvation and abandonment, and predation by leopards, hyenas and wild dogs. Up to 80% of lion cubs will die before the age of two. Both male and female lions may be ousted from prides to become nomads, although most females usually remain with their birth pride. When a pride becomes too large, however, the youngest generation of female cubs may be forced to leave to find their own territory. When a new male lion takes over a pride, adolescents both