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Artificial nests can enhance the breeding success of endangered African penguins, a new study by an international team of researchers from South Africa and the United Kingdom has found.
Endemic to Southern Africa, the African penguin (Spheniscus demersus) is now critically endangered. After a brief recovery in the 1990s and early 2000s, the species’ population has declined by nearly 90 per cent over the past 70 years.
The research, published in the British Ecological Society’s journal Ecological Solutions and Evidence, revealed that the African penguin population fell from nearly 93,000 breeding pairs in 1956 to around 9,900 in 2023. The study pointed to food scarcity and human disturbances as primary factors driving this alarming decline.
To counteract these threats, artificial nests or burrows have been placed in many penguin colonies across South Africa and Namibia over the past three decades, aiming to enhance breeding habitats and success rates.
The species breeds naturally in burrows dug into guano (a natural substance composed of the excrement of birds, bats, and seals), which protects them from the extreme heat of their environment. These burrows also protect their broods from harsh winds and rain, which can be fatal to chicks.
However, the penguins prefer the artificial nests over burrows dug in guano, researchers from Nelson Mandela University noted. The new 12-year study found that breeding success was 16.5% higher in artificial nests compared to natural ones.
Conducted in eight of the largest African penguin colonies in South Africa, the study monitored four types of artificial nests alongside natural ones, tracking eggs from laying through to successful chick fledging.
Interestingly, no single artificial nest design proved universally superior across all colonies. Each shelter type exhibited different strengths and weaknesses, depending on the specific threats faced by penguins in that colony.
The most recent ceramic nests, designed with slanted roofs and a 5 cm air gap between layers, showed the highest overall effectiveness, though results varied by location. A-frame pine plywood nests, cement nests made with fibreglass, and fibreglass burrows — designed to mimic natural penguin burrows — were also tested.
Professor Lorien Pichegru, lead researcher from the Institute for Coastal and Marine Research at Nelson Mandela University, noted that “the most effective artificial nest designs were colony-specific, with different colonies facing different threats.”
For example, land colonies such as Boulders Beach are vulnerable to mammal predators, while colonies lacking vegetation, like Bird Island, face risks from sun exposure, he added.
Wooden boxes deployed on Robben Island in 2001 increased fledging success compared to nests under vegetation, while fibreglass nests saw varied performance across different colonies. On Robben Island, fibreglass nests outperformed vegetation nests, but results were mixed on other islands like Bird Island and Dyer Island.
The study also warned that breeding success in natural nests may be slightly underestimated due to logistical challenges in monitoring them. Natural nests in easily accessible areas may be more exposed to predators and the elements, impacting breeding outcomes, the authors said.
“We also weren’t always able to follow the fate of individual birds or breeding pairs closely over multiple years in this study,” said Richard Sherley, co-author from the University of Exeter, adding that it is unclear how much of the benefit comes from "the best" penguins choosing to breed in artificial nests.
“We can’t be certain how much of the benefit we measured comes from the ‘best’ penguins actively choosing to breed in artificial nests. So, it would also help conservation strategy if we could understand what makes an artificial nest attractive to penguins or not,” he added.
Pichegru added that future research in this area could enable creation of more effective artificial nest designs. “Understanding the mechanisms by which artificial nests improve breeding success at different colonies could help to improve future artificial nest designs. For instance, is it improved protection from predators; is it decreasing heat loads on eggs or is it something else?” he said.
However, the authors stressed that artificial nests alone will not save the species. Pichegru highlighted poor food availability, oil spills, underwater noise pollution, and predation as major threats to African penguins, adding that “biologically meaningful fishing exclusion zones around their major colonies are urgently needed” to ensure their survival.