Evaluation of the chimpanzee breeding program at the Southwest Foundation for Biomedical Research.

The history of the chimpanzee (Pan troglodytes) breeding colony of the Southwest Foundation for Biomedical Research was evaluated over a 24-year period to determine age at conception, breeder rearing history, maternal competence, and infant rearing history. The records of 107 breeders and 268 live births were reviewed. Of the breeders with known rearing histories, 40 were wild-born (12 male and 28 female), 16 were reared by their mothers for at least 1 month (8 male and 8 female), and 13 were removed from their mothers immediately after birth (2 males and 11 females). The age of successful mating for males ranged from 7 to 32 years and for females from 7 to 41 years, although the upper limit indicates the age of the population and not reproductive senescence. The mother's rearing history was related to her maternal competence, defined as caring for an infant for at least 1 month. Of the wild-born females, 82% (18/22) were competent mothers. For females that had been reared in captivity with their mothers for 1 to 12 months, 71% (5/7) were competent. For females that had been removed from their mothers immediately and reared in a nursery by humans, only 14% (1/7) were competent. The rearing strategies have changed during the period under consideration. The number of infants reared by their mothers increased in the 1980s, while the number of infants removed from their mothers immediately for experimental reasons decreased and dropped to zero in the 1990s. Information on the history of the breeding colony has been used to make management decisions and to determine the expectations of the Southwest Foundation chimpanzee breeding program.