The critically endangered African penguin has several predators to fear, including gulls, seals and sharks at sea, and leopards, caracals, domestic dogs and mongoose on land. A recent study has now documented the first confirmed case of yet another predator: a Cape clawless otter was observed preying on the African penguins of a mainland colony.
African penguins (Spheniscus demersus) historically bred on islands around South Africa and Namibia, where they were safe from larger mainland mammalian predators like leopards and caracals. However, as growing human settlements kept large predators at bay, the penguins began establishing mainland colonies.
One such mainland colony is in Simon’s Town, along South Africa’s southwest coast. Between 2020 and 2023, the penguin population there has declined from 1,100 breeding pairs to 870, the study’s authors write.
Local authorities first observed Cape clawless otters (Aonyx capensis), which typically eat fish and crustaceans, near the Simon’s Town penguin colony in September 2022. They also found seven penguin carcasses, but couldn’t confirm what had killed them.
In March 2023, authorities finally caught an otter in the act: they observed and photographed a female otter attacking penguins. They rescued two adult penguins and recovered carcasses of three others and sent them to the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) for autopsy.
With the predator visually confirmed, SANCCOB researchers were able to record and identify the characteristic measurements, location and nature of the wounds linked to otter attacks. “This will help separate otter predation from other predators,” Albert Snyman, study lead author and a SANCCOB researcher, told Mongabay by email.
With African penguin populations in dramatic decline, some conservationists say that identifying the penguins’ predators and deploying the appropriate management actions is important.
Rangers, for instance, caught the female otter responsible for the 2023 penguin predation and moved it to an undisclosed, faraway location within Table Mountain National Park. There were no further otter attacks on Simon Town’s penguins until more than a year later, suggesting “that the initial relocation of the predator was successful and that appropriate or predator specific interventions can help to reduce mortalities,” Snyman said.
From July-September 2024, however, authorities recovered five more penguin carcasses from the Simon’s Town colony that exhibited injuries consistent with an otter attack.
The researchers aren’t sure why the otters around Simon’s Town targeted penguins again. Otters have also been spotted around another mainland colony at Stony Point, but there haven’t been any confirmed cases of those otters preying on penguins.
Snyman said the recent observations suggest that otters could potentially become an issue to other mainland colonies and that further monitoring is needed.
Banner images: A Cape clawless otter. Image by Mark Paxton via Wikimedia Commons (CC BY-SA 3.0).
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