Interbirth intervals in a captive group of Japanese macaques.

Interbirth intervals in a captive group of Japanese macaques were found to be shortened and inconsistently affected by stillbirth and infant loss within 6 months of life. The reduction in the length of the interval between successive births was in all probability the result of shorter periods of lactation and larger amounts of body fat stored by the well-nourished females of the study group.