A new study by researchers at Stellenbosch University explores the paleo-historical picture of the geographical range of African penguins in southern Africa, in order to provide new insight into the current vulnerability of the last remaining penguin species in Africa.
The research was conducted to estimate the population numbers of the African penguin during the last Ice Age and determine the effect of climate change on the species. The study shows that, over the past 22,000 years, the rising sea levels resulted in a tenfold reduction in suitable nesting habitats for African penguins, sending their population numbers into steep decline.
The researchers estimate that between 6.4 million and 18.8 million individuals could have occupied the southern Cape waters during the Last Glacial Maximum, but due to rising sea levels 15,000 to 7,000 years ago, the habitat for the African penguins to nest on went into a steep decline. The study also reveals that, during the Last Glacial Maximum, there were at least 15 large islands along the southern and western coastlines of southern Africa, with the largest one being 300 square kilometres in area, that were swarming with hundreds of millions of marine birds and penguin colonies.
The main objective of the study is to show that there have been major changes in habitat availability over the last 22,000 years, which could have had a massive effect on penguin populations.
The researchers argue that this finding raises grave concerns about the current vulnerability of African penguins, but it also highlights the potential for a reserve of resilience in the species that may be leveraged for its conservation and management in an uncertain future.
The researchers suggest that changing sea levels would have necessitated the need for multiple relocations of breeding colonies of African penguins on time scales of centuries, if not even shorter time scales, and intense competition for breeding space as island habitat became greatly reduced in size. This historical flexibility of response provides some leeway for conservation managers to make available suitable breeding space, even in mainland sites, as long as appropriate nesting sites are made available. The study also suggests that, given the chance of relocation, the African penguin has the potential to survive as it has in the past.
However, the researchers argue that modern human pressures such as commercial fishing, climate change and habitat destruction pose a significant challenge to the persistence of the species. In 1910, Dassen Island was teeming with an estimated 1.45 million penguins, but by 2019, South Africa's entire African penguin population had declined to only 13,600. Approximately 97% of the current penguin population in South Africa is supported by only seven breeding colonies. The International Union for the Conservation of Nature classified the African penguin as endangered in May 2005.
The research provides insights into the history of the African penguin population, which can help guide conservation efforts to ensure the continued survival of the species in the future.
The study suggests that conservation managers need to focus on creating suitable breeding spaces for the African penguin, as the species is highly adaptable and has a strong colonisation ability, which could be leveraged for its conservation and management in the face of an uncertain future. The researchers emphasise the importance of addressing modern human pressures on the species, such as commercial fishing, habitat destruction, and climate change, to ensure the long-term survival of the African penguin.