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Acevedo J.,Fundacion CEQUA | Carreno E.,Arturo Prat University | Torres D.,Retired Chief of Project INACH 018 | Aguayo-Lobo A.,Instituto Antartico Chileno | Letelier S.,Museo Nacional de Historia Natural
Polar Biology

The diet of Weddell seals (Leptonychotes weddellii) varies regionally, and fish and cephalopods are thought to be the most important food source. However, there is limited information on the cephalopod component of the Weddell seal’s diet in the South Shetland Islands. We investigated cephalopod remains in the diet of Weddell seals by analysing 21 scats collected on three beaches at Cape Shirreff, Livingston Island, Antarctica, from 1 to 20 February 1999. Although the number of scats is small and collected from only 1 month a long time ago, fish and cephalopods were present in 21 and 16 of the scats, respectively. Only cephalopods of the order Octopoda were represented. Thaumeledone sp. was the most abundant prey species in terms of numbers, followed by Pareledone charcoti and P. turqueti. The latter two species showed the highest frequency of occurrence in scats (10 and 9, respectively). Graneledone macrotyla, Opistoteuthis sp., Argonauta sp., Haliphron sp. and Thaumeledone sp. are new species identified in the diet of Weddell seals in the present study, but all made a negligible contribution to their diet at Cape Shirreff. Our findings agree with previous dietary studies of Weddell seals at other localities in the South Shetland Islands and the Antarctic Peninsula, which showed a relatively greater contribution of octopods to the diet compared with squid in summer. © 2015, Springer-Verlag Berlin Heidelberg. Source

Torres D.,Retired Chief of Project INACH 018 | Aguayo-Lobo A.,Instituto Antartico Chileno
Polar Biology

Non-offspring maternal care should be common in phocids, but their occurrence would be uncommon among otariids due to the high costs of raising offspring, particularly lactation, and an efficient recognition system that allow for accurate recognition during the frequent mother–pup re-associations. However, non-offspring maternal care has been documented in some otariid species. While the phenomenon in general is not novel among the colonially breeding seals, the exclusive care to a single pup by two lactating females for an extended time is a behavior scarcely documented in natural population. In an extension of this allonursing care, we document the first case of the kidnapping of a pup with subsequent shared nursing in Antarctic fur seal including data on the effect of this interaction on the pup’s growth. While all other lactating females nursed exclusively their own pups, the shared nursing was advantageous for the pup because he grew noticeably larger (in weight and axillary girth) than other of his cohort, particularly after 50 days. This advantage would have been influenced by the asynchrony of the foraging cycle of the biological and foster mother, which resulted in a higher attendance on shore than any other male pups. Although several explanations have been hypothesized for allolactation in mammals, our observations suggest a misguided parental care, associated with recognition errors by the foster mother whose pup was stillborn. © 2015 Springer-Verlag Berlin Heidelberg Source

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