African penguins are the only penguin species found in Africa. They play important roles in their ecosystem, both as a food source for seals and sharks and also as predators of small fish, such as anchovies and sardines.
Highly social and very vocal, African penguins are native to the waters of South Africa. But these endangered birds are now struggling to survive the human impacts and the unfolding climate crisis of the Anthropocene. However, their climate story goes back much further than our modern epoch. They’ve been through this before: after the last Ice Age, they were among the planet’s first climate refugees.
What the tale of the African penguin exemplifies is a simple truth: biodiversity loss and climate change have always been two sides of the same coin.
Today, anthropogenic climate change—along with the intensive use and destruction of natural ecosystems through agriculture, fishing and industry—has sparked an unprecedented loss of biodiversity that continues to worsen. Unfortunately, though, this biodiversity crisis, known as the sixth mass extinction, and the climate crisis have often been viewed as two separate catastrophes. But now, an international team of researchers is calling for the adoption of a brand-new perspective.
If you were standing on the coast of southern Africa about 20,000 years ago, you may have been able to spot several large islands overrun with hundreds of millions of marine birds and penguin colonies.
African penguins: climate refugees once more
Imagine that you’re standing on the west coast of southern Africa about 20,000 years ago, during the Last Glacial Maximum. In the distance, you see at least 15 large islands—the largest measuring about 115 square miles in area—swarming with hundreds of millions of marine birds and penguin colonies.
Now, pretend that you’re standing in the same place 15,000 to 7,000 years ago. This time, the sea level has risen more than 320 feet. The large islands have been covered up until only small hilltops remain above water. This scenario, played out over the past 20,000 years or so, has resulted in a tenfold reduction in suitable nesting habitat for African penguins, sending their population numbers into steep decline.
This paleo-historical picture of the geographical range of African penguins was created by evolutionary genomics scientists in the Department of Botany and Zoology and the School for Climate Studies at Stellenbosch University in South Africa. Publishing their study in the African Journal of Marine Science on April 20, 2023, the researchers say that this paleo-historical image of multiple millions of African penguins stands in stark contrast to today’s populations, especially since another, post-1900 collapse.
African penguins can be recognized by the pink patches of skin above their eyes, which are used to regulate body temperature. When these penguins get too warm, blood is sent to these patches to be cooled by the outside air, making the glands appear pinker.
In 1910, a one-square-mile island off the west coast of Africa, Dassen Island, was teeming with an estimated 1.45 million penguins. However, by 2011 South Africa’s entire African penguin population decreased to 21,000 breeding pairs. By 2019, they had further declined to only 13,600. In its latest assessment in 2019, the International Union for the Conservation of Nature (IUCN) classified the African penguin as endangered. Today, approximately 97 percent of the current population in South Africa is supported by only seven breeding colonies.
Paleo penguins: past persisters
So, what did the coastline of southern Africa look like during the last Ice Age? And what can that tell us about current African penguin population numbers?
Since penguins prefer to breed on islands to escape mainland predators, the researchers used topographic maps of the ocean floor off the coast of southern Africa to identify potential historical islands lying at 32 to 425 feet below current sea levels. For islands to qualify as suitable for penguins, they needed to offer protection from land-based predators and had to have adequate foraging grounds for anchovies and sardines within a 12-mile radius.
To escape mainland predators, penguins often prefer to breed on islands. A female digs a burrow or simply uses a hollow under a bush or a rock, where she lays two eggs. Both the male and the female incubate the eggs for up to 40 days. Chicks are fed and cared for by both parents for their first month. They then form groups with other chicks for safety. After three to five months, the chicks leave the colony and start living independently.
Assuming that sea levels were much lower during the last Ice Age, the scientists identified 15 large islands off the west coast of Africa. The largest is a 115-square-mile island lying 425 feet below the sea surface. Taking into account rising sea levels over the past 15,000 to 7,000 years, they then identified 220 islands which would have provided suitable nesting conditions for the penguins—some barely bigger than a rock.
Based on the earliest available population density data, the scientists then calculated penguin number estimates based on accessible island area, assuming that penguins usually nest at most 0.3 miles from the shore.
Following this reasoning, between 6.4 million and 18.8 million individuals could have occupied southern cape waters during the Last Glacial Maximum. Due to rising sea levels 15,000 to 7,000 years ago, however, nesting habitat for African penguins went into a steep decline.
African penguins are challenged by food scarcity from competition with commercial fisheries.
This study demonstrates that there have been major changes in African penguin habitat availability over the last 22,000 years, which could have had a massive effect on the birds. But it also highlights the potential for a reserve of resilience in the animals that may be leveraged for their conservation and management in an uncertain future.
A millennial-scale set of selection pressures would have favored a strong colonization ability in African penguins. Changing sea levels would have necessitated the need for multiple relocations of breeding colonies on a time scale of centuries; and there would have been intense competition for breeding space as island habitat became greatly reduced in size. This historical flexibility of response in the penguins provides some leeway for today’s conservation managers to make suitable breeding and nesting space available—even in mainland locations—and to provide enough access to marine food resources to prevent extinction of the species.
The scientists believe that African penguins are survivors. Given half a chance, they’ll be able to hang on. Island-hopping saved them in the past, and they’re experts at doing it.
The biggest driver of biodiversity loss is habitat destruction: humans transforming habitats for their own purposes. Resource-extractive industry practices—such as clear-cutting trees, drilling for gas and oil, and mining—destroy habitats. Real-estate development in places that were previously off-limits is also causing animal populations to drop. Climate change is worsening the effects. Cheetahs are a case in point: as human populations grow and expand, agriculture, roads and settlements destroy the open grasslands that this big cat calls home.
But the question is, even given the chance for relocation, how much more will it take to persist considering the additional rise of modern, human pressures, such as competition for food? Going against the commercial fishing industry and humanity in general for the same food source, penguins—and other marine life—probably have a higher climb than they’ve ever experienced before.
Two crises: one fight
This Stellenbosch University study points out a salient fact: the biodiversity crisis and the climate crisis are interdependent, mutually amplifying and can’t be approached as two separate entities.
In a study just published in the journal Science, 18 international experts show the connections between the climate crisis and the biodiversity crisis; and they present solutions for addressing both catastrophes and mitigating their social impacts, which, they state, are already dramatic.
Scientists estimate that soils—mostly, agricultural ones—could sequester over a billion additional tons of carbon each year. This has led policymakers to increasingly look to soil-based carbon sequestration as a “negative emissions” technology—that is, one that removes CO2 from the air and stores it somewhere it can’t easily escape.
In the Science study, the experts describe the rapidly worsening loss of species with the aid of sobering figures: they estimate that human activities have altered roughly 75 percent of the land surface and 66 percent of the marine waters on our planet. Approximately 80 percent of the biomass from mammals and 50 percent of plant biomass have been lost, they believe, while more species are in danger of extinction than at any other time in human history. Global warming and the destruction of natural habitats not only lead to biodiversity loss, but also reduce the capacity of organisms, sediments and soils to store carbon, which in turn exacerbates the climate crisis.
Because each organism has a certain tolerance range for changes to its environmental conditions (such as temperature), global warming is also causing species’ habitats to shift. Mobile species follow their temperature range and migrate to higher elevations or toward the poles (on land) or to greater depths (in the ocean). Sessile organisms, such as corals, can only shift their habitats very gradually, over the course of many generations. They are caught in a temperature trap, which means that large coral reefs could, in the long term, disappear entirely. And, too, mobile species could run into climatic dead ends in the form of mountain summits, the coasts of islands and landmasses, at the poles and in the ocean’s depths, if they can no longer find any habitats with suitable temperatures to colonize.
To address these multiple crises, the researchers propose a combination of emission reductions, intelligent land-use management practices, protection and restoration measures, and promotion of cross-institutional capabilities. Of course, a massive reduction of greenhouse-gas emissions and reaching the 1.5-degree target continue to be at the top of the priorities list. In addition, however, at least 30 percent of all land, freshwater and marine zones must be protected or restored to prevent the greatest biodiversity losses and to preserve the abilities of natural ecosystems to function. This, in turn, will help us to combat climate change.
Modern land-use management policies must include havens for species that make food harvests possible, such as bees.
For example, the extensive restoration of just 15 percent of the zones that have been converted for land use could be sufficient to prevent 60 percent of the expected extinction events. This would also allow up to 300 gigatons of atmospheric carbon dioxide to be removed and fixed on a long-term basis; that amounts to 12 percent of all the carbon emitted since the dawn of the industrial era.
The study’s authors call for a modern approach to land-use management, one in which protected areas are not viewed as isolated refuges for biodiversity. Rather, they need to be part of a world-spanning network on land and sea that interconnects comparatively untouched regions via migration corridors for various species. Indigenous peoples and local communities, especially, must be supported for their efforts to protect and restore nature. When it comes to regions that are intensively used for agriculture and fishing, the focus should be on sustainability.
It’s acknowledged that both resource-conserving forms of use and a reliable food supply for humans must be ensured. Here, the concepts that lead to intensified carbon dioxide uptake and carbon fixation in biomass and soils are to be given priority. Also, sufficient havens must be created for species that make harvests possible to begin with, such as the insects that pollinate fruit trees. Lastly, in cities, improving the carbon dioxide balance should be paramount.
Probably one of Earth’s first climate refugees, African penguins are again facing a climate challenge.
Two conventions: one Earth
All of this will only work, say the experts, if biodiversity preservation, climate protection and social advantages for local communities are pursued simultaneously. We’re unlikely to reach the new global biodiversity, climate and sustainability targets planned for 2030 and 2050 if individual institutions fail to collaborate more intensively. Take, for example, the separate United Nations Convention on Biological Diversity and the United Nations Framework Convention on Climate Change. They address the two crises separately and are focused on the national interests of the parties to the conventions. A more comprehensive approach is urgently needed if we still hope to reach the targets.
African penguins may have been one of Earth’s first climate refugees. Today, they are again facing a climate challenge that threatens them with extinction—and the planet with biodiversity diminishment.
There is only one Earth. When trying to protect its nature, thinking on the scale of a world might broaden our perspectives and problem-solving abilities.
Here’s to finding your true places and natural habitats,
Candy
