Evidence of allomaternal nursing across one-male units in the Yunnan snub-nosed monkey (Rhinopithecus Bieti).

Baoping Ren,Karen Rosenberg,Ming Li,Dayong Li,Paul A Garber

doi:10.1371/journal.pone.0030041

Abstract

BackgroundAllomaternal nursing, common in several species of social mammals, also has been reported in nonhuman primates. However, the function of this behavior in enhancing infant survivorship remains poorly understood.Methodology and Principal FindingsThe study was conducted on a free-ranging group of the Yunnan snub-nosed monkey (Rhinopithecus bieti) in the Baimaxueshan Natural Reserve. Direct observation and ad libitum sampling were used to record allocare behavior during a 20 month field study. R. bieti exhibits a multilevel social organization in which a large single troop, consisting of over 100 individuals, is divided into many one-male units (OMUs: 6∼41). These OMUs coordinate their daily activities, and feed, forage, travel, and rest together. Here we report on one case of infant temporary adoption in which an adult female from one OMU engaged in allomaternal nursing and cared for an infant from a different OMU of the same troop. This event began when the mother and her five-month-old infant were found to became separated accidentally. The victim infant was observed staying in another OMU. Over the next several days we observed a lactating female in the new OMU to care for and nurse both her infant and the immigrant infant, who also was tolerated by and cared for by the harem male.Conclusions and SignificanceOur findings suggest that lactating primate females are primed to care for young infants and, that the misdirected parental care hypothesis may offer the strongest explanation for allomaternal nursing in R. bieti.

Highlights

Allomaternal care, including allomaternal nursing, defined as a lactating female providing milk for another’s offspring [1], is reported to be common in several social mammals such as bats [2], carnivores [3], rodents [4] and seals [5]
Our findings suggest that lactating primate females are primed to care for young infants and, that the misdirected parental care hypothesis may offer the strongest explanation for allomaternal nursing in R. bieti
In the case of tamarin (Saguinus) and marmoset (Callithrix) monkeys, there is evidence that allomaternal care is critical for infant survivorship [11]

Summary

Introduction

Allomaternal care, including allomaternal nursing, defined as a lactating female providing milk for another’s offspring [1], is reported to be common in several social mammals such as bats [2], carnivores [3], rodents [4] and seals [5]. The ‘misdirected parental care’ hypothesis states that social and hormonal factors associated with lactation may result in a mother inadvertently nursing another female’s offspring [1]. Roulin argues this could occur in group-living species in which several females give birth during the same period of the year [1]. The function of this behavior in enhancing infant survivorship remains poorly understood

Methods

Results

Discussion

Conclusion