Research Reveals First Archaeological Evidence of Antarctic Apex Predator in South African Pleistocene Deposits
Have you ever watched Happy Feet or National Geographic? If you have, you may know what a leopard seal is. As a child, this animal scared the bejesus out of me. I have no idea why; I was fine with almost every other animal; even the thought of swimming with sharks was less threatening. But leopard seals gave me the creeps.
Recently, I was able to publish my own research along with my supervisor and co-authors. The study dealt with a palaeoenvironmental reconstruction of Waterfall Bluff Rock Shelter (Eastern Cape) from ca. 39,000 -5,000 years Before Present (BP). What made the study incredibly exciting was not only the finding of the remains of the extinct African giant buffalo but also the tooth of a leopard seal.
Why was this in any way interesting (other than the fact that I used to be incredibly afraid of these creatures?)
Not only was this the first ever reported archaeological find of leopard seal remains along the coast of South Africa, but it is also extremely unique as leopard seals do not occur naturally in South African waters; it is much too warm. This means that the environment may have been cold enough to allow these creatures to come so far north from their usual habitat.
Waterfall Bluff
Waterfall Bluff is a rock shelter located around 24m above the modern coastline next to the Mlambomkulu River waterfall. It has remains of human occupation spanning as far back as Marine Isotope Stage 3 (a relatively warm period, which interspersed thousands of years of colder ones) around 39,000 BP until around 5,000 years BP. This is pretty impressive as the sea levels across the globe would rise and fall during glacial and inter-glacial periods. This means that usually, during warmer periods, when sea levels were higher, coastal sites would be submerged and thus unsuitable for human occupation. However, Waterfall Bluff is unique in that its positioning meant it never submerged during these interglacial times. This makes it one of only a few sites that provide unique glimpses into the lives of hunter-gatherers who lived at coastal sites during interglacial times.
To determine how and if Waterfall Bluff experienced environmental change that may have influenced hunter-gatherer behavior despite being one of the few sites not submerged during interglacial times, we identified the faunal remains and compared them to Waterfall Bluff’s environment today.
At present, the site sits within the Eastern Mpondoland, known for its diverse landscapes featuring gorges, valleys, hills, and plateaus. It is home to various animals, including bushbuck, duikers, bontebok, leopards, black-backed jackals, caracals, fish, and fur seals.
The Mpondoland Paleoclimate, Paleoenvironment, Paleoecology, and Palaeoanthropology Project (P5) first excavated the site in 2015. More than 17,000 artifacts, including marine shellfish, fish, charcoal, plant remains, and fauna, were recovered from these excavations.
Amongst the animals found were tortoise, porcupine, vervet monkey, southern reedbuck, eland, bushbuck, oribi, dassies, mountain reedbuck, blue duiker, common duiker, and much more. However, the most intriguing finds were the extinct African giant buffalo and leopard seal.
But what does all this mean?
The Ancient Environment of Waterfall Bluff
The faunal remains indicate that Waterfall Bluff’s environment likely stayed relatively stable for thousands of years, featuring grasses and bushes throughout. This, in turn, enabled a mosaic of animals to live there, from the grass-loving Oribi to the obligate browser such as bushbuck.
Even during glacial times, when the coast was up to 8km away, ancient hunter-gatherers continued to hunt and forage along the coast, bringing their fish and seal spoils back to the shelter. The site seemed ideally situated, enabling abundant resources even during the harshest periods. Since the site never submerged beneath the waves, we can study how humans adapted to these changing environmental conditions along the coast.
The findings also included a African giant buffalo phalange (finger/toe bone). This species was first collected from Modder River in the Free State in 1839 by Mr. Martin Smith, whom naturalist Andrew Geddes Bain eventually persuaded to inform the Geological Society of London of his intriguing find. The find was presented to the Society via a letter penned by none other than Charles Darwin, who had yet to write up his revolutionary theory of evolution. However, the specimen would not be recognized or given a scientific name until almost 50 years later. Since then, many more specimens have been found, and it has been determined the creature had horns measuring 3m from tip to tip and weighed in at almost 2,000kg (~4,410 lbs). It had lived in southern Africa from about 1 million years BP until it went extinct roughly 10,000 years BP.
The specimen found at Waterfall Bluff was dated to between 11,060 and 10,990 years BP, making it among the last of its kind before it went extinct about 1,000 years later.
However, the leopard seal find was by far the most intriguing. African giant buffalo remains had been found before in South Africa, but archaeological leopard seal remains were unheard of.
The Leopard Seal
Leopard seals are apex predators whose habitat is restricted to the pack ice surrounding the Antarctic and sub-Antarctic islands. They can grow up to 3m long (as long as the horns of the African giant buffalo, let that sink in) and weigh up to 380kg (~ 837lbs). Their name derives from its black-spotted coat, making it look a bit like a snow leopard rather than the gold and black usually associated with leopards. They are ambush predators that will lurk beneath ice shelves, waiting to snare unsuspecting penguins and other prey resting on the water’s surface or jumping in from the pack ice above. Despite how ferocious they look (and their creepy smile—just my opinion), the creature’s diet consists of 50% kill, followed by penguins, pinnipeds (fur seal grey seals, etc.), fish, and cephalopods (such as octopus, squid, and cuttlefish).
Now, leopard seals are not commonly found in South Africa or anywhere beyond the sub-Antarctic, for that matter. Usually, reports of leopard seals beyond this point deal with lost juveniles or incredibly sick and emaciating individuals (although it is likely they became sick and emaciated because they ventured too far into warmer water, where their main food source and pack ice are lacking).
In South Africa, only a handful of leopard seal sightings have been recorded (dead and alive), including one in 1946 near East London, another over 20 years later in 1969 in Hout Bay, a dead seal that was reported to the East London Museum in 1994, and a single living individual in 2014 by Kevin Cole, a principal scientist at the East London Museum, near Cove Rock. In 2021, another individual was spotted once in Cape Town and again in Yzerfontein; that’s five sightings in almost 100 years.
Pack ice is incredibly crucial for their survival; not only does it facilitate their hunting, but they require it for breeding and for the existence of the arctic krill, which makes up the majority of their diet. You see, the winter sea ice is vital for krill larvae. However, too much winter ice and specific krill distribution ranges and spawning grounds are cut off.
The leopard seal remains from Waterfall Bluff date to 22,560-21,900 years BP; this makes them fall squarely into the Last Glacial Maximum (LGM), the coldest part of the last ice age. While it is possible that this was an isolated instance of a leopard seal straying too far from its home range. The climatic conditions during the LGM were cold enough to suggest that leopard seal colonies and hunting ranges may have extended further north than today. The colder waters would have enabled leopard seals to hunt, breed, swim, and survive much closer to the southern African coast. Additionally, greater amounts of Arctic pack ice in the south may have forced certain krill populations, usually restricted to East Antarctica and the Arctic peninsula north, to find better spawning grounds, forcing the leopard seals to follow.
The fauna at Waterfall Bluff suggests a mosaic environment that remained relatively stable for thousands of years, enabling hunter-gatherers to continue to live there even as the environments in surrounding areas changed. It was in this context that not only the remains of the extinct African giant buffalo but also those of a leopard seal were found.
The tooth of this species provides the first direct evidence of leopard seal recovered from Pleistocene and Holocene archaeological faunal assemblages along South Africa’s coast. This finding, alongside palaeoenvironmental data, may indicate a substantial ecological shift in the coastal environment during the LGM.
I hope you enjoyed my first piece of published research. Let me know your thoughts. Was this leopard seal simply a lost individual, or was it just the first of many?
(P.S. A second leopard seal may also have been discovered at another site but has not yet been published; our leopard seal may not have been alone.)
(P.P.S I am no longer irrationally afraid of leopard seals).
References
Australian Antarctic Program. (2018). Leopard seal. Australian Antarctic Program. https://www.antarctica.gov.au/about-antarctica/animals/seals/leopard-seal/
Bonillas-Monge M. (2018). Historical dynamics of leopard seal (Hydrurga leptonyx) and southern elephant seal (Mirounga leonina) populations in the Southern Ocean [unpublished doctoral dissertation]. Durham: Durham University.
Esteban, I., Bamford, M. K., House, A., Miller, C. S., Neumann, F. H., Schefuß, E., … & Fisher, E. C. (2020). Coastal palaeoenvironments and hunter-gatherer plant-use at Waterfall Bluff rock shelter in Mpondoland (South Africa) from MIS 3 to the Early Holocene. Quaternary Science Reviews, 250, 106664.
National Geographic. (n.d.). Leopard Seal. National Geographic. Retrieved December 6, 2024, from https://www.nationalgeographic.com/animals/mammals/facts/leopard-seal?loggedin=true&rnd=1733482680603
Oster, S., Reynard, J. P., Cawthra, H. C., Esteban, I., Pargeter, J., & Fisher, E. C. (2024). Late Pleistocene and Holocene fauna from Waterfall Bluff Rock Shelter, Mpondoland, South Africa. South African Journal of Science, 120(11/12). https://doi.org/10.17159/sajs.2024/17449
Rossouw, L. (2001). The extinct giant long-horned buffalo of Africa (Pelorovis antiquus). Culna, 2001(56), 14-15.
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