Archive for June 2015
A remarkably complete giant penguin is now on display at the Waikato Museum in New Zealand. This penguin was discovered not by professional paleontologists from a museum or university, but by the Hamilton Junior Naturalist (JUNATS), a group of young scouts. The penguin bones were spotted embedded in the rocky shoreline, awash in the shallow waves. According to the report, the JUNATS originally though they had come across “an old rusty propeller”. Indeed, the orange-brown colors of the bone have the appearance of distressed iron, lending to their charm. Once their mentors established that the group had a fossil on their hands, an excavation effort began. You can see the process in the video below.
Now, the fossil is in the Waikato Museum curated by Salina Ghazally, which includes some neat accompaniments such as a touchscreen interactive with 3D bone scans. Experts including Dr. Daniel Thomas are investigating the bones too, to determine their affinities. This penguin is important because although New Zealand is the world capital in fossil penguin diversity, almost all of the fossils that have been described were discovered on the South Island. The new fossil is the best ever discovered on the North Island and will be key in establishing how penguin species overlapped or differed in the two regions millions of years ago. I had the chance to see this superb fossil in 2011, and it is well worth the trip. Like my own home museum, the Bruce Museum, the Waikato Museum hosts art, science and history exhibitions, so there is always something new to see.
King Penguins and Emperor Penguins share a similar appearance. In fact, the poor King Penguins in the Central Park Zoo are called Emperors by roughly 99% of the visitors I have overheard talking about them (also overheard: one child told his mother than penguins definitely know about Captain America). Yet, Kings and Emperors have very different environmental preferences. Whereas Emperors breed on sea ice sheets, Kings require sites that are ice-free year-round to carry out their unique breeding cycle, which spans over a year from egg-laying to fledging of the juveniles.
A recent study by Dr. Emiliano Trucchi and colleagues looked at the genetic structure of Kings from Possession Island. Possession Island is part of the Crozet Archipelgo in the Indian Ocean, where roughly half of the world’s population of King Penguins lives. These data revealed that the population in this region was very low about 20,000 years ago.
Why might this be? At 20,000 years before present, the Earth was locked in a cold period known as the Last Glacial Maximum (often referred to as the Ice Age). In North America glaciers extended right down to New Jersey. In the Southern Hemisphere, winter sea ice extended far north of the modern day limits, enveloping many islands that stand in open water all year round today, including Possession Island. This would presumably make it impossible for King Penguins to successfully breed on many of the islands they favor today. So what happened to all those penguins? One possibility raised by the authors is that they moved North to ice-free beaches in places like New Zealand. This hypothesis is supported by a few tantalizing fossils that suggest Aptenodytes penguins once occurred in New Zealand (and maybe even South Africa).
As climate warmed and sea ice retreated, King Penguins were able to reclaim sites like Possession Island as breeding colonies. This led to a marked increase in the Crozet archipelago population, as shown by the DNA analyses. While it may seem like this particular group of penguins benefited from melting ice 20,000 years ago, playing the warming tape forward raises a troubling specter. Other studies have shown reproductive rates in the modern Crozet Archipelago King Penguin populations have been negatively impacted by increased sea temperatures because warmer temperatures force the penguins to swim farther from their nests to find food-rich cold waters, requiring more energy use and increasing the time at sea.
Trucchi E, Gratton P, Whittington JD, Cristofari R, Le Maho Y, Stenseth NC, Le Bohec C. 2014 King penguin demography since the last glaciation inferred from genome-wide data. Proc. R. Soc. B 281: 20140528.