Saliva sharing in the allied rock-wallaby, Petrogale assimilis

Abstract

Prolonged licking of the mouth of one individual by another has so far been reported for two species of rock-wallaby and the red kangaroo. It may occur in other macropodids. It is suggested that the primary function of lip-licking is the transfer of saliva to the fore-stomach of the licker so as to maintain water content of digesta at a sufficient level for efficient digestive fermentation. Lip-licking may be a useful behavioural indicator that water intake from milk, vegetation or drinking water is inadequate.The occurrence of the behaviour outside the mother–young relationship is indicative of the high level of cooperation that has evolved in Petrogale assimilis.