Abstract

Although allosuckling, the lactation of non-filial offspring, can be a costly behavior, it has been reported in several species across a wide range of mammalian orders. Monotocous species such as ungulates exhibit this behavior less frequently than polytocous species, and most cases have been reported among captive specimens. A case of allosuckling of a free-ranging guanaco (Lama guanicoe) calf is reported. Allosuckling observed in this species may represent opportunistic behavior by the calf, supporting the "milk theft" hypothesis. © 2008 Japan Ethological Society and Springer.