Modern-day penguins prosper in colder areas, so why did the New Zealand penguin fail to endure?(Image credit: Richard McManus via Getty Images)ShareShare by:
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Around three million years ago, an ancient relation of the present’s sizable penguins — emperors and kings — inhabited Aotearoa New Zealand.
We are aware of this because our recent investigation details an impressive fossilized cranium of a great penguin discovered on the Taranaki coastline.
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In contrast to emperor penguins, however, the Taranaki great penguin had a considerably more robust and elongated beak. It potentially resembled a king penguin (Aptenodytes patagonicus), but significantly larger.
During that era, the world experienced warmer conditions than it does presently. But as the climate became cooler, this penguin disappeared.
We suggest that frigidity wasn’t the reason, as crested and little penguins in New Zealand endured the same alteration and persisted. Great penguins relocated south and now exist in the icy expanses of Antarctica. Therefore, what caused their ancient counterpart to go extinct?
The fossil cranium (top) of the extinct great penguin in its estimated original configuration, contrasted with craniums from a king penguin (middle) and an emperor penguin (bottom).
The sediments that currently constitute beach-side bluffs in South Taranaki were placed down during a period when global temperatures stood at about 3°C above those of the pre-industrial age. Fossils from this time are changing our awareness of how biodiversity might react to escalating temperatures.
For example, Aotearoa provided a habitat for box fish and monk seals, both of which persist as (sub)tropical species presently. In a peculiar contradiction, they coexisted alongside great penguins — now exclusively located in considerably colder climates — in ancient New Zealand.
The northernmost breeding locations of king penguins presently reside around latitude 46.1°S in the subantarctic Crozet Islands, where seawater temperatures attain 3-10°C. From that point, it solely gets colder towards the elevated latitudes where emperor penguins reside.
Today, great penguins are confined to subantarctic isles and the coastline of Antarctica (map on the left). But ancient New Zealand served as home to a defunct species of great penguin approximately three million years ago, during a time in Earth’s past recognized as the mid-Piacenzian Warming Period.
Three million years ago, Aotearoa’s great penguins stretched as far northward as 40.5°S, where South Taranaki was situated during that time. They hunted for sustenance in waters reaching 20°C, significantly warmer than their counterparts encounter today.
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This agreeable state came to an end with the Pleistocene ice ages approximately 2.58 million years ago. Ice extension and sea level moved backward and forward as temperatures went up and down and ultimately reduced. But why would this type of chilling wipe out giant penguins, which flourish in polar environments today, from New Zealand?
Giant aerial predators
Fossil data for giant penguins in Aotearoa is restricted, and the specific causes for their end remain ambiguous. However, their mere presence implies they were less restricted by sea surface temperatures than previously assumed. Another factor must be involved.
Until approximately 500 years in the past, Aotearoa served as the hunting locale of the giant Haast’s eagle and the massive Forbes’ harrier. These were sizable raptors. They incorporated large avians like moa into their diet. Their forerunners arrived from Australia within the last three million years.
Artist’s rendering of the extinct great penguin that inhabited New Zealand about three million years ago.
Based on observations of living great penguins, the Taranaki great penguin almost definitely formed extensive exposed colonies along the coast. These might have been effortless targets for a giant eagle or harrier preying from above.
Conversely, the smaller penguins persisting in Aotearoa today display more secretive breeding habits. They nest in tunnels, natural fissures, and dense foliage, and tend to traverse beaches during the night, which may have facilitated their evasion of aerial predators.
However, predation on terra firma constitutes merely one theory to assist in clarifying why these penguins became defunct in the area while others persevered. Additional possibilities encompass modifications to the marine setting.
We are aware that diminished food accessibility can be devastating for penguins; however, it remains challenging to comprehend why this would specifically target the great penguins.
Significantly, our investigation furnishes novel awareness into the habitat tolerances of great penguins. Both king and emperor penguins can presently endure temperatures soaring up to 20°C greater than those they generally hunt for sustenance in.
Three million years ago, their relative underwent comparable warmth. As the globe persists in warming, we must recall that the geographic extent of a species can alter as circumstances shift.
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The marine ecosystem of Aotearoa will transition into the habitable zone of numerous novel species, rendering inquiries into the prior warm period more critical than ever before.
We wish to recognize our research co-author Dan Ksepka from The Bruce Museum, Kerr Sharpe-Young for unearthing the fossil, and Ngāti Ruanui and Ngāruahine for endorsing the collection and investigation of fossils from their district.
This revised piece is reissued from The Conversation under a Creative Commons permit. Peruse the initial piece.
Daniel ThomasHonorary Academic (School of Biological Sciences), University of Auckland, Waipapa Taumata Rau
Daniel Thomas received a doctorate in geology and zoology from the University of Otago in 2009, where his studies centered on penguin progression. He finished postdoctoral fellowships at the University of Cape Town and a role at the Smithsonian’s National Museum of Natural History, where he scrutinized fossils and the origins of feather hue. Thomas subsequently served as a zoology instructor at Massey University in Auckland and currently functions as an honorary academic in the School of Biological Sciences at the University of Auckland.
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