Daytime deliveries observed for the ring-tailed lemurs of the berenty reserve, Madagascar

In the Berenty Reserve, Southern Madagascar, of the 16 deliveries recorded for ring-tailed lemurs from 1995 and 1997, 10 cases occurred during daytime hours (07:00 - 16:59). Four mothers lost contact with their troop members during parturition, but were able to rejoin them after about one hour. No a ttack from the individuals of the neighboring groups or predators on the mo thers or their newborn infants was observed, whereas, other females of the mother's own troop attacked them after delivery in two cases. Such daytime delivery may have originated from the circadian rhythm of the species' noct urnal ancestors, who might have given birth during the daytime. This patter n may now be a non-adaptive feature, in agreement with the "evolutionary di sequilibrium hypothesis (EVDH)."