First Record of a Twin Birth in Chimpanzees of the Mahale Mountains National Park, Tanzania

Abstract

Newborn chimpanzee (Pan troglodytes schweinfurthii) twins were observed in the Mahale Mountains National park. This is the first observation at Mahale of a multiple birth from 135 births recorded during 29 years of research at this site. On 22 January 1994, a ca.16-year-old female was first seen with her female twins. Each infant was estimated to be only two-thirds the normal size, but their combined weight and the double amount of attention that had to be given to their care made the mother's burden very heavy. She had to pay close attention to the infants even when she rested. The mother often stopped to rest every 10-20 m while traveling, and often walked bipedally for 2-3 m at a time, gripping the twins by the nape of their necks. She was never seen to lift the infants to her nipples although they often showed oral rooting for nipple behavior and vocalized in distress. When the mother was next seen on 29 January, her twins were gone.