Sub-Antarctic fur seals depredate northern rockhopper penguins at Nightingale Island, Tristan da Cunha

• Published in: Polar Biology
• Main Authors: Bester, Marthan Nieuwoudt, Dilley, B.J., Davies, D., Glass, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2021
• Subjects: Predation risk; Nightingale Island; South Atlantic Ocean; Northern rockhopper penguin (Eudyptes moseleyi); Sub-Antarctic fur seal (Arctocephalus tropicalis); Antarctic; Southern Ocean; Austral; Indian; Tristan; Gough; Amsterdam Island; Antarc*; Antarctic Fur Seal; Antarctic Fur Seals; Polar Biology; Rockhopper penguin
• Online Access: http://hdl.handle.net/2263/78087; https://doi.org/10.1007/s00300-020-02688-1

The most plausible hypothesis for declining population trends of some marine top predators at the northern extent of their breeding ranges in the Southern Ocean is that it results from environmental change. Sub-Antarctic fur seals Arctocephalus tropicalis are opportunistic and pelagic foragers that feed on a variety of fish, cephalopods, and crustaceans throughout their range. Penguins are also targeted, but to what extent remains uncertain, with only two records to date: Amsterdam Island, South Indian Ocean, where they kill and feed on northern rockhopper penguins Eudyptes moseleyi; and Gough Island, the southernmost island in the Tristan da Cunha archipelago, South Atlantic Ocean, where they are suspected to be significant predators of northern rockhopper penguins based on an unprecedented number of penguin carcasses (> 100) found floating at sea in 2011. We report the first documented records of such predations from the northern islands in the Tristan archipelago. Over three austral summers (2015–2017), northern rockhopper penguins with severe injuries were frequently observed at Nightingale Island. The cause of the wounds was unknown, but seal or shark attacks seemed probable. In January 2019, the first confirmed sighting of a sub-Antarctic fur seal, predating a healthy northern rockhopper penguin at sea off Nightingale Island was recorded. It remains uncertain whether the large A. tropicalis population at the Tristan da Cunha islands is significant predators of northern rockhopper penguins, but this could partly explain the significant recent decrease in northern rockhopper penguin population numbers. http://link.springer.com/journal/300 2021-06-07 hj2020 Mammal Research Institute Zoology and Entomology