Alloparenting in Steller sea lions (Eumetopias jubatus): correlations with misdirected care and other observations

Abstract

Alloparental care is rarely observed in Steller sea lions (Eumetopias jubatus) where maternal care is extended to a single pup for up to 1 year or more. However, we observed 28 allonursing events and one case of adoption at a small breeding rookery in the western Gulf of Alaska between the years 2001 and 2005. Multiparous and primiparous females were observed nursing nonfilial individuals with equal frequency, but primiparous females spent significantly more time nursing nonfilial individuals. Multiparous females allowed allonursing only while sleeping and unaware while most primiparous females were aware that they were allonursing. These results are consistent with the misdirected-care hypothesis suggesting that primiparous (presumably younger) females nurse nonfilial pups due to inexperience, whereas multiparous (presumably older) females are victims of milk stealing during times of inattentiveness. Nonfilial pups were aggressively tossed most often during the pupping season and only by multiparous females, while allonursing events occurred more frequently after the pupping season. Starveling pups were not cared for by any female, but two were attended by a single bull during separate autumn seasons.

Allosuckling in reindeer (Rangifer tarandus): Milk-theft, mismothering or kin selection?

“…If allosuckling is driven by calves stealing milk, lactating females should reject NF offspring and may become aggressive towards NF offspring, and NF offspring should adopt the perpendicular or parallel positions to allosuckle, instead of the antiparallel position, to avoid being discriminated (Reiter et al, 1978;Zapata et al, 2009). Evidence for the milk-theft hypothesis has been reported, among other studies, in red deer (Cervus elaphus) (Landete-Castillejos et al, 2000), river buffalo (Bubalus bubalis) (Murphey et al, 1995), guanacos (Lama guanicoe) (Zapata et al, 2009), bactrian camels (Camelus bactrianus) (Brandlová et al, 2013), and multiparous Steller sea lions (Eumetopias jubatus) (Maniscalco et al, 2007). Offspring have been hypothesized to allosuckle due to misdirected maternal care, known as mismothering, suggesting no kin discrimination and kin recognition mechanisms.…”

“…If allosuckling is caused by lactating females being unable to discriminate their own offspring, lactating females should not reject NF offspring, and NF offspring should equally adopt the antiparallel, parallel and perpendicular positions to allosuckle (Zapata et al, 2009). Evidence for the mismothering hypothesis has been reported in domestic (Ovis aries) and wild (O. canadiensis) sheep (Hass, 1990;Welch and Kilgour, 1970), red deer (Bartoš et al, 2001b), Hawaiian monk seals (Monachus schauinslandi) (Boness, 1990), primiparous Steller sea lions (Maniscalco et al, 2007), and Saharan arrui (Ammotragus lervia) (Cassinello, 1999). Allosuckling bouts reported in grey seals (Halichoerus grypus) can be accounted for by the lack of efficient kin recognition mechanisms (McCulloch et al, 1999).…”

Effect of nursing behaviour, sex of the calf, and parity order on milk production of buffaloes

“…Some non-mutually exclusive hypotheses have been proposed to explain why lactating females nurse alien offspring: misdirected parental care (Packer et al, 1992), reciprocity (Ekvall, 1998;Engelhardt et al, 2015;Glonekov et al, 2016), kin selection (Pusey and Packer, 1994;Ekvall, 1998;Eberle and Kappeler, 2006;Engelhardt et al, 2016), evacuation of leftover milk (Riedman and Le Boeuf, 1982;Wilkinson, 1992), inexperience of females (Murphey et al, 1991;1995), and milk theft (Murphey et al, 1995;Maniscalco et al, 2007;Zapata et al,2009;Engelhardt et al, 2014;Glonekov et al, 2016).…”

A case of suckling and allosuckling behaviour in captive common hippopotamus

“…In common hippos, the occurrence of allosuckling was suggested but not proven (Smuts and Whyte, 1981). The allosuckling in monotocous species has been mostly explained by kin selection (African elephant Loxodonta africana - Lee, 1987; feral horse Equus caballus - Cameron et al, 1999; red deer Cervus elaphus - Bartoš et al, 2001;cattle Bos taurus -Víchová and Bartoš, 2005), milk evacuation hypothesis (evening bat Nycticeius humeralis - Wilkinson, 1992; northern elephant seals Mirounga angustirostris - Riedman and Le Boeuf, 1982), or as misguided parental behaviour (Saharan arrui Ammotragus lervia - Cassinello, 1999;guanaco Lama guanicoe -Zapata et al, 2009; Steller sea lion Eumetopias jubatus - Maniscalco et al, 2007), and milk theft hypothesis (red deer - Landete-Castillejos et al, 2000). However, it should be noted the limits of this case report: (i) lack of replication and most importantly, (ii) impossibility of observing in our setting milk thefts from unrelated mothers or competition between calves.…”