for National Geographic News
Motherhood is an equal-opportunity employer for female lions.
A long-term study of lions in Africa shows that the females living among a group of lions consistently produce similar numbers of surviving offspring and raise them collectively.
Such egalitarianism is rare in nature. Most cooperative animal societies, such as mongooses and wolf packs, are despotic, leaving reproduction to a single, domineering female.
The researchers discovered that female lions form remarkably egalitarian societies that are characterized by two key features: symmetrical relationships and a voluntary system of communal cub-rearing in which all the qualified females engage in reproduction.
Because this reproductive pattern is so different from that of other cooperative animal groups, close study of the lions' behavior may improve scientists' understanding of the factors that lead to egalitarianism, said Craig Packer, a professor of ecology, evolution, and behavior at the University of MinnesotaSt. Paul.
Packer is co-author of a July 27 report in Science that describes the findings of the research, which lasted three decades and involved observations of lions at Serengeti National Park and Ngorongoro Crater, both in Tanzania.
Lions live in groups of three to thirty individuals, called prides. Within each pride is a group of closely related femalesmothers, daughters, sisters, and cousins. The number of individual females typically ranges from two to eighteen, depending mainly on how much prey lives in the surrounding area or migrates through a pride's territory.
Females do most of the hunting for the members of a pride and remain with the group for their entire lifetime, which can extend to 18 years. They mate and give birth to offspringusually one to three cubsevery two or three years, unless the cycle is disrupted by the invasion of males from outside the group.
Males, on the other hand, aren't so home-bound. They leave their native prides once they reach the age of two to four and band together with several other males, often from the same pride, to form a coalition.
Once the males in a group have reached full maturity and are ready to reproduce, they set off together to seek out an existing pride they can overtake. But first, they have to evict the males already living in the targeted group.
This confrontation is often violent and the weaker male lions are killed. The ousted lions that survive the rivalry go off in search of another pride to claim as their own. Male lions that manage to avoid early death can live to about the age of twelve.
SOURCES AND RELATED WEB SITES