Diurnal births and perinatal behavior among wild patas monkeys: Evidence of an adaptive pattern

Data from a 2-year field study of patas monkeys (Erythrocebus patas) in Kenya support our earlier suggestion that diurnal births are a species-typical pattern of patas. In this respect patas are very unusual, as all existing information shows that nocturnal births are typical of both captive and freeranging monkeys. Patas do not give birth at night because to do so would render ineffective their night-resting strategy which reduces vulnerability to predation at night. Giving birth during the day, however, does not eliminate the risk of being preyed on; nor are all times of day equally favorable for giving birth. Our field data suggest that a patas female gives birth at those times of day when she is least likely to lose contact with her group or to encounter predators.