Penguin predation by extra-limital sub-Antarctic fur seals Arctocephalus tropicalis

• DOI: 10.1007/s00300-021-02956-8
• Publication Date: 2021-10-19T03:39:52Z
• Authors: Rodrigo Machado; Martin Sucunza Perez; Bernardo A. Arús; Renan C. de Lima; Silvina Botta; Victor Hugo Valiati; Larissa R. Oliveira; Caio J. Carlos
• Keywords: 0106 biological sciences; 14. Life underwater; 01 natural sciences

Sub-Antarctic fur seals, Arctocephalus tropicalis, are widely distributed in the southern hemisphere, breeding on islands north of the Antarctic Convergence in the South Atlantic, South Indian, and Southwestern Pacific Oceans. At their breeding grounds, sub-Antarctic fur seals feed on a variety of fish, cephalopods, crustaceans, and occasionally, on penguins. According to the literature, the species feeds mainly on squid and fish, in the southern Brazilian coast, during the non-breeding period and far away from its breeding colonies. Here, we present records of predation on penguins by sub-Antarctic fur seals off southern Brazilian coast (29°20′S, 49°43′W to 33°44‵S, 53°22′W). We examined the gastrointestinal contents of 61 sub-Antarctic fur seals collected from 1987 to 2019. Remaining of penguins were found in the gastrointestinal tracts of three adult males (4.9%). We identified feathers, and other bird parts by comparing them specimens from scientific collections and illustrations in the literature. Seabirds found in the gastrointestinal tracts of the three sub-Antarctic fur seals were most probably Magellanic Penguins, Spheniscus magellanicus. To our knowledge, this is the first study reporting predation on penguins by sub-Antarctic fur seals far from their breeding colonies. Although penguins are not among the main prey of sub-Antarctic fur seals, our results suggest that they occasionally feed on penguins during the non-breeding period along the southern coast of Brazil.