Maternal behavior and infant congenital limb malformation in a free-ranging group of Macaca fuscata on Awaji Island, Japan

We studied the relationship between maternal behavior and infant disability in 12 mother-infant dyads for the first 5 weeks of infant life in the free-ranging Japanese macaque (Macaca fuscata) group on Awaji Island, Japan, from May to September 2001. Congenital limb malformations are prevalent in this population, and as such carry implications for behavior and conservation. We did not detect any differences in maternal activity budgets, mother-infant physical contact, infant holding, and overall nursing and infant transport time between mothers of non-disabled infants, disabled infants that were able to cling to their mothers, and disabled infants whose limb structure prevented clinging. Mothers of infants with limb malformations severe enough to prevent normal clinging behavior manually supported their infants during nursing and locomotion significantly more than other mothers did theirs. Increased support-carrying and support-nursing, and higher frequencies of holding the infant to one's ventrum, suggest that mothers of extensively malformed infants may be investing more to facilitate the survival of their offspring and that infant disability appears to be influencing maternal behaviors in this population.