Artificial nests can boost the breeding success of endangered African penguins, but different designs are more effective at different colonies according to a new study by an international team of researchers from South Africa and the UK. The findings are published in the British Ecological Society journal, Ecological Solutions and Evidence.
A new study, led by researchers at Nelson Mandela University, which monitored the breeding success of African penguins for 12 years across South Africa has found that artificial nests outperformed natural nests and increased breeding output by 16.5%.
However, the researchers also discovered that no single style of artificial nest was the most effective across penguin colonies, with each type having strengths and weaknesses. The newly designed, double layered ceramic nests were generally the most effective type of nest compared to earlier designs, but this was not universal.
Professor Lorien Pichegru, at the Institute for Coastal and Marine Research, Nelson Mandela University, and lead researcher said: "The most effective designs of artificial nests were colony-specific, with different colonies facing different threats. Penguins at land colonies such as Boulders Beach face threats from mammals, whereas penguins at colonies devoid of vegetation such as Bird Island face sun exposure. Different artificial nest designs were more suited to responding to different threats."
The results show that artificial nests can be an effective conservation measure for African penguins, but because there isn't a one-size-fits all design, colony specific conservation strategies are required.
The continued decline in African penguin numbers means that further conservation action is needed beyond artificial nests, primarily through increasing food availability.
"The main causes of the recent decline in African penguin numbers are poor food availability, oil spills, underwater noise pollution and predation." Explained Professor Pichegru. "Biologically meaningful fishing exclusion zones around their major colonies are urgently needed."
African penguins are one of the most threatened seabird species globally and face an extremely high chance of becoming extinct. Populations have declined by 90% in the last 70 years to around 8,500 breeding pairs.
To combat a lack of nesting habitat for these burrowing seabirds, which leaves them vulnerable to predators and extreme weather, artificial nests have been deployed at various colonies in South Africa for over 30 years.
In this study the researchers looked at the breeding success of African penguins over a 12-year period at the 8 largest African Penguin colonies in South Africa. The researchers checked both natural nests and 4 types of artificial nests weekly from when eggs were laid until chick fledgling or nest failure.
The artificial nests included the newly designed ceramic nests which have slanted roofs and 5cm airgap between layers, A-framed pine plywood nests (the oldest design), cement nests made of a mixture of fibreglass and cement, and fibreglass burrows which mimic the shape of natural penguin burrows.
The researchers warn that breeding success in natural nests may have been slightly underestimated in the study due to the logistical challenges of monitoring them. Natural nests monitored for breeding success are often chosen in accessible areas to reduce disturbance and therefore can be more exposed to weather and predators.
"We also weren't always able to follow the fate of individual birds or breeding pairs closely over multiple years in this study" said Dr Richard Sherley, a co-author from the University of Exeter.
"That means 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.
Professor Pichegru agreed that future research in this area could make artificial nest designs even more effective. "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 decrease heat loads on eggs or something else?"
