Technological advances have enabled the observation of foraging behaviour in wild marine animals. We can observe where they go, how deep they dive, how much energy they expend, and with the use of animal-borne cameras we can capture specific foraging behaviours. Here we describe a newly observed foraging behaviour in African Penguins Spheniscus demersus in which they target fish located in jellyfish tentacles. As animal-borne cameras have only been deployed on African Penguins since 2015 it is unclear whether this behaviour is novel or previously unobserved. The behaviour appears to be opportunistic and beneficial to the African Penguins as it enables them to catch stationary prey. As the availability of the African Penguin's traditional schooling fish prey changes in the southern Benguela Current ecosystem due to climate change and overfishing, opportunistic foraging strategies like this could enable African Penguins to supplement foraging success at a low energetic cost.

African Penguins Spheniscus demersus are endemic to southern Africa where they breed in South Africa and Namibia. Their numbers have declined by >80% since the first comprehensive census in the 1970s (Sherley et al. 2020). As a consequence, the species was listed as 'Endangered' on the IUCN Red List in 2010 (Sherley et al. 2020) and may soon meet the criteria for being listed as 8Critically Endangered' (Sherley et al. 2024). The common prey species of the African Penguin, determined through stomach flushing on breeding adults, have traditionally been Southern African Anchovy Engraulis capensis (hereafter 'Anchovy') and Sardine Sardinops sagax (Crawford et al. 2011).

However, following the collapse of Sardine stocks in the northern Benguela in the 1960s and 1970s, the Namibian population of African Penguins switched to feeding almost exclusively on Bearded Goby Sufflogobius bibarbatus (Ludynia et al. 2010). In the southern Benguela Current, the Sardine stock has been in a poor state for the last c. 15 years following a combination of climate change and fishing pressure (Coetzee et al. 2008; Coetzee et al. 2022), and although Anchovy remains abundant, its availability to seabirds may have changed following an eastward displacement of spawning habitat (Crawford et al. 2019; Mhlongo et al. 2015).

The change in forage fish distributions and abundances in the Benguela ecosystem, alongside declining African Penguin populations, has led to substantial research interest in how the availability of prey resources to African Penguins may be changing (e.g. Crawford et al. 2006, 2011; Campbell et al. 2019). The colony on Robben Island, South Africa, is the focus of one of the longest running monitoring projects on African Penguins (Crawford et al. 2006; Leith et al. 2022). In addition to monitoring metrics like breeding success and chick condition on land (e.g. Campbell et al. 2019; Sherley et al. 2013), we have deployed GPS dive loggers on breeding African Penguins since 2008, providing important information for management, especially where they are foraging and how this varies through time (e.g. Campbell et al. 2019). However, at this time, dive data allow only for inference on when African Penguins are foraging, but not details about what they are eating.

Many diet analysis techniques for use on seabirds are necessarily highly invasive, e.g. stomach flushing (Wilson 1984). It can be difficult to justify these invasive techniques from a contemporary viewpoint, particularly when working with endangered species like the African Penguin. Fortunately, less invasive methods are increasingly available. The use of camera technology to study seabird diet is becoming widespread (e.g. Gaglio et al. 2018b; Mattern et al. 2018), with animal- borne video cameras providing valuable information on prey species, when the resolution of footage is high enough (McInnes et al. 2017; Watanabe & Takahasi, 2013; Ponganis et al. 2000). Furthermore, video cameras have the added benefit of documenting foraging behaviour and success (e.g. Sutton et al. 2020; Sutton et al. 2021; Watanabe & Takahasi 2013).

This paper reports observations from camera footage collected on African Penguins from Robben Island foraging at sea across four years: 2018, 2019, 2022 and 2023. In particular, we report a behaviour that we do not believe to have been reported in this species before, where individual African Penguins target fish located amongst jellyfish tentacles.

We thank Robben Island Museum (RIM) for permission to carry out research on the island, accommodation, and ferry transport; in particular, Sabelo Madlala and Inga Sipuka supported the fieldwork. Sue Kuyper and our institutions provided logistical support, and we thank Andrew de Blocq, Taron Morris, Andile Mdluli, Nicholas Ngcathu, and Kiah Tasman for their assistance in the field. This study was conducted under permit from the Department of Forestry, Fisheries and the Environment (DFFE permit numbers: RES2018/18, RES2019/50, RES2022/23 and RES2023-20), in partnership with Robben Island Museum, and under animal ethical clearance from the University of Exeter (Reference numbers: 2018/2404, eCORN001760 and 528178). Funding was provided by the Earthwatch Institute (http://earthwatch.org/), the Pew Charitable Trusts (through a Pew Fellows Program in Marine Conservation award to RBS), and the San Diego Zoo Wildlife Alliance. The views expressed in this paper are those of the authors and do not necessarily reflect the views of The Pew Charitable Trusts or any other funder.

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