The African penguin has a homelessness crisis. But human-made shelters, it turns out, can help.

Starting in the 1800s, mining of guano for fertilizer robbed these flightless, knee-high birds of their natural homes. The penguins dug burrows into the accumulated bird droppings at colonies along Africa’s southern coast to escape the heat, wind and predators that threatened them and their young.  As the natural habitat vanished, the birds resorted to hiding inside thickets of vegetation or even nesting out in the open.

That change in living quarters is one reason why the African penguin is in danger of vanishing. In 2023, there were just 9900 breeding pairs, a roughly 90% decline since the 1950s.

But things would be even worse without a campaign to build artificial homes for the penguins. Over 14 years, survival of eggs and chicks at South African colonies increased by more than 15% in these unnatural homes, when compared to the ones penguins scraped together for themselves, according to a new study in Ecological Solutions and Evidence.

While that’s good news for the birds, it turns out that there is no single artificial burrow that outranks the rest.

“The most effective designs of artificial nests were colony-specific, with different colonies facing different threats,” says Lorien Pichegru, at Nelson Mandela University’s Institute for Coastal and Marine Research.

The problem with natural open air or vegetation nests is that it can leave penguins and their young more vulnerable to overheating or predation by gulls, mongooses and other creatures eager for a penguin snack.

Over the last three decades, conservationists have been erecting little huts for the African penguins, with increasing levels of technological ingenuity. The initial ones are effectively a crude A-frame cabin built of plywood. The newest version, a multi-layered affair crafted from ceramics, bears a passing resemblance to the famed Sydney Opera House. In between there have been small concrete canopies like tiny Quonset huts, and fiberglass shells buried underground to simulate natural burrows.

Pichegru and her colleagues wanted to scrutinize whether these shelters were making a difference and, if so, which ones were the best. They collected data gathered between 2008 and 2022 that tracked the survival of eggs and tiny chicks at eight nesting sites on mainland South Africa and coastal islands. A variety of different faux burrows had been deployed at these locations.

Overall, the newest ceramic hut was the top performer. It features a single, small entrance, which deters predators. The design also uses two layers of material with an air gap in between and ventilation holes to reduce temperatures. But it wasn’t the best at every colony, the scientists found.

The cement tunnels performed almost as well overall. But while they had some of the highest survival rates at three sites, they had the lowest performance at one spot. By contrast, the fiberglass burrows were generally a dud, except on one island, where chicks did best in them. The old plywood shelter even came out on top in one location (although there were no cement nests and very few ceramic ones there).

The findings affirm that, like so many things in the natural world, a one-size-fits-all approach isn’t the best.

Pichegru suspects the differences are tied to the differing dangers. For example, at Bird Island, where sun exposure is the big hazard, the airy cement shelters performed well, even if their two large openings were more open to predators. By contrast, similar shelters were the worst performers at Boulders Beach, where mammals prey on the penguin nests. “Different artificial nest designs were more suited to responding to different threats,” she said.

But a city’s worth of synthetic penguin shelters won’t be enough to save the birds, which are also being battered by a oil spills, underwater noise pollution, and overfishing of food, such as anchovy and sardine, on which the birds depend, warned Pichegru. “Biologically meaningful fishing exclusion zones around their major colonies are urgently needed.”

Pichegru, et. al. “Decades of artificial nests towards African penguin conservation—Have they made a difference?” Ecological Solutions and Evidence. Oct. 16, 2024.

Photos: ©The African Penguin Nest Project