Allosuckling behavior in the Australian sea lion (Neophoca cinerea): An updated understanding

摘要

Allosuckling, or the nursing of nonfilial pups by females, has been reported in several phocids (Stirling 1975, Riedman and Le Boeuf 1982, Boness 1990, Boness et al. 1992, Perry et al. 1998) and can occur at very high rates in some species (e.g., up to 90% in Hawaiian monk seals, Monachus schauinslandi; Boness et al. 1998). By contrast, observations of allosuckling in otariids suggest that this behavior is much rarer (Stirling 1975, Georges et al. 1999, Childerhouse and Gales 2001, Gemmell 2003, Haase 2007, Maniscalco et al. 2007). The highest reported rate of allosuckling in an otariid was 11% in Antarctic fur seals, Arctocephalus gazella (Gemmell 2003). Allosuckling has alternatively been hypothesized to be costly, beneficial, or neutral to the parties involved. Due to the cost of lactation, mothers are expected to bear the cost of allosuckling unrelated young (Clutton-Brock et al. 1989). Conversely, mothers may gain fitness benefits through allosuckling related young or by gaining maternal experience (Riedman 1982). Immunologically, young may gain benefits by suckling from more than one female, but may also face the cost of pathogen transmission themselves and between mother and foster mother (Roulin and Heeb 1999). Moreover, by attempting to steal milk, pups can be seriously injured by approaching nonmothers (Harcourt 1992a, b). Alternatively, as in Hawaiian monk seals, allosuckling may impose no apparent cost on the females (Boness 1990).