Why you should always trust a penguin

Linda Barclay Isles

Monday 24 November 2025

This week, Research Spotlight shines on trustworthy African penguins!

What’s your name and what do you research? 

My name is Jacqui Glencross, and I’m a seabird ecologist. Earlier this year, I completed my PhD investigating how fishing influences the foraging behaviour of African penguins. I’m broadly interested in how human-driven pressures—such as fishing and climate change—affect the ecology of marine animals, especially seabirds.

Why are penguins such an interesting animal to study? 

Penguins—like many seabirds—are fascinating to study because they reliably return to land during the breeding season. This makes it much easier to attach biologging devices, such as GPS trackers, to monitor where they go and how they behave at sea. Thanks to this technology, we can gather detailed information about their movements without needing to follow them directly. When we deploy devices on African penguins during breeding, they’re typically retrieved within a day. They’re remarkably dependable birds—so dependable, in fact, that we like to say you should always trust a penguin—and our device recovery rate is very high.

African penguins are also particularly compelling because, as of last year, they became the first penguin species to be classified as Critically Endangered on the IUCN Red List. The study system I worked with during my PhD is especially unique: it includes a globally unique fishery-closure experiment. While we know that competition with fisheries can drive seabird population declines, it’s extremely rare to be able to study the effects of fishing by experimentally removing the pressure. This makes African penguins an invaluable species for understanding how human activities shape marine ecosystems.

Tell us how your work combines on the ground fieldwork and statistical models?  

The Robben Island African Penguin Project has been monitoring the breeding colony since the early 2000s, and since 2008 we’ve also been deploying GPS and other biologging devices on penguins from this colony. This long-term effort has generated a huge dataset that has already helped inform local policy aimed at protecting the species.

My work focuses on understanding the fine-scale details of penguin foraging behaviour and how it is influenced by competition with commercial fisheries. Using GPS, time-depth, acceleration, and animal-borne camera data from breeding birds allows us to reconstruct not only where penguins go, but how they dive, how they move, and what they encounter at sea.

We then use these detailed behavioural data to feed into statistical models that test how penguin foraging changes in response to fishing activity. For example, we can now show that penguins complete fewer foraging dives when a fishery is operating nearby. Findings like this help us uncover the mechanisms linking fishing pressure to penguin population declines—and ultimately support more effective conservation decisions.

What are you working on at the moment?  

Right now, I’m focused on publishing the final pieces of research from my PhD. One of my favourite chapters involved building a highly detailed energetics model. Using the full suite of biologging data collected from the Robben Island colony, we estimated the energy penguins expend during a single foraging trip.

We examined fine-scale aspects of each trip—such as dive depth, the number of prey-capture attempts, and how often those attempts were successful. Then, drawing on results from my earlier work, we simulated what a penguin’s energy expenditure would look like if the fishery were not present. This work is helping us understand how fishing pressure affects not just penguin behaviour, but the energetic costs they face while trying to feed themselves and their chicks.

Whats next?  

For the penguins: 
New fishery-closure areas have recently been introduced around many colonies, so understanding their impact on penguin populations is a key priority. At Robben Island, a weighbridge has now been installed to record the outgoing and incoming weights of penguins. This will allow us to track how foraging success—measured by how much food birds bring back to the colony—changes over time. Collaborators are also planning to expand on my energetics work by incorporating this new weight data, which I think will lead to some very exciting insights.

For me: 
I’m looking forward to starting a new role as a Marine Ornithology Advisor at NatureScot. I’ll be drawing on what I learned during my PhD about the interactions between seabirds and fisheries, but applying it to species closer to home. That said, I don’t think I’ll ever stray too far from my African penguins—there will definitely be more papers and projects involving them in my future.

If you would like to feature in research spotlight, have had a paper accepted or want to talk more broadly about how to engage the wider media with your research, please contact Senior Communications Manager Ruth Sanderson [email protected]