For at least 22,000 years, the African penguin has been struggling to survive due to habitat loss. Scientists are now looking to the past to learn more about why they can best help the adorable feathered creatures today and in the future. A study published April 20 in the African Journal of Marine Science paints a paleohistoric picture of where these survivors of climate change lived and moved when the last Ice Age came to an end, and how that changed over time.
According to the study, the African penguin, also called the black-footed penguin, Cape penguin or Jackass penguin, lived on 15 large islands off the coast of southern Africa more than 20,000 years ago. During this period called the Last Glacial Maximum, massive ice sheets dominated a large part of the Earth, and it ended about 15 to 20,000 years ago. Following this climate change, sea levels began to rise as the ice melted, effectively sinking the islands. Rising water reduced suitable nesting habitat for penguin colonies tenfold over the next 22,000 years.
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To help them paint this picture, the team used topographic maps of the ocean floor to find potential islands that lie between 32 and 426 feet below current sea level. Penguins use the islands as breeding grounds to escape predators on the mainland and also need suitable feeding grounds for sardines and anchovies within a radius of about 12 miles.
Assuming that sea levels were lower during the last Ice Age, the team identified 15 large islands possibly lying off the southwestern coast of Africa, with the largest approximately 115 miles long and 426 feet. below the surface of the sea. By taking into account the rate of sea level rise over the past 15,000 to 7,000 years, they found 220 islands that would have been suitable nesting spots for penguins.
By comparison, some of the largest modern islands with penguins off the southwest coast of Africa are Robben Island, less than two miles long, Dassen Island, less than a mile long, and Possession Island, also less than a mile long. of a mile long, registering altogether less than two miles long.
The study estimates that between 6.4 million and 18.8 million individual penguins could have lived among these islands during the Last Glacial Maximum, before numbers began to plummet.
These changes in habitat availability over the past 22,000 years “could have had a massive effect on penguin populations,” co-author and University of Stellenbosch ecologist Heath Beckett said in a statement. “These populations are now experiencing additional human pressures on top of this in the form of climate change, habitat destruction, and competition for food.”
According to Beckett, this new paleohistoric picture of penguins across the southern African islands contrasts with the current reality of a post-1900 collapse of the African penguin population. Dassen Island was once teeming with around 1.45 million penguins, but South Africa’s entire African penguin population collapsed to 21,000 breeding pairs in 2011. As of 2019, it has further declined to 13,600, and about 97% of the current population in South Africa remains. by seven breeding colonies.
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“Changes in sea levels would have required the need for multiple relocations of African penguin breeding colonies on time scales of centuries, if not even shorter time scales, and intense competition for breeding space as the island’s habitat has been greatly reduced in size,” he said. Beckett. “This historic flexibility of response provides some leeway for conservation managers to make suitable breeding space available, even at mainland sites, as long as suitable nesting sites are available.”
Some additional questions raised by this research surround the relocation of penguins and the analysis of how much more the species can handle as human pressures continue to increase and competition for food intensifies.
However, despite the alarming declines in the population and their ongoing struggle, the team notes that these findings highlight the resilience of the African penguin as a species and that this could be harnessed for its conservation and management in an uncertain climate.
“It is a total survivor and, given the chance, they will endure,” co-author and University of Stellenbosch biologist Guy Midgley concluded in a statement. “Island hopping saved him in the past, they know how to do this.”