Maternal cradling laterality and neonate nipple preference in the Sichuan snub-nosed monkey ( Rhinopithecus roxellana)in Qinling Mountains

In order to understand factors influencing the development of laterality in maternal cradling behavior and neonate nipple preference of Qinling golden monkeys ( Rhinopithecus roxellana) ,we collected behavioral data using scan sampling from 32 newborn infant - mother pairs . We collected 3 675 samples of neonate nipple preference and 3 661 samples of ma- ternal cradling laterality. W e calculated a lateral bias index ( LBI)by subtracting the number of left-sided observations ( L ) from the number of right-sided observations ( R)and dividing by the total number of observations ,i. e. ( R - L / ( R + L ) . We found a left-side group-level preference of maternal cradling in primiparous females ( t ( 6 ) = - 3 890,P = 0 008) ,and a significant left-side nipple group-level preference in infants who were born to primiparous females ( t ( 6 ) = - 3 731,P = 0 010) . We found no group-level preference direction among multiparous females,( neonate nipple prefer- ence:t( 2 4 ) = 0 854,P = 0 402;maternal cradling laterality:t ( 2 4 ) = 1 955,P = 0 062) . Moreover,m ost ( 8 of 9)fe- males differed in their direction of maternal cradling laterality among successive procreating periods ( N 1 = 8,N2 = 1,P = 0 039) . Our results suggest that experience may affect neonate nipple preference and thus affect maternal cradling laterality in this species.