The paper summarizes seven years of records of the reproductive history of two wild prides of lions (Panthera leo L.) in the Serengeti National Park, Tanzania. These records are analyzed to demonstrate ways in which lion reproduction is influenced by their social group and by changes in that group.
Females gave birth at any time of year; they did so sooner if their previous litter died. Females synchronized births with other pride members. Takeover of the pride by new males resulted in a drop in the birth rate. Most cubs died, before two years old. Birth synchrony resulted in better cub survival. The arrival of new males resulted in an increase in cub mortality. Females came into oestrus synchronously with other pride members. Males had a much longer effective reproductive life if they had male companions.
The proximate causes of these features of lion reproduction are considered, and the evolution of aspects of the organization of reproduction in lions is discussed.