Things have been quiet at March of the Fossil Penguins lately, in large part because I have busy moving north. This summer, I started my tenure as the Curator of Science for the Bruce Museum. Now that things are settling down, there are some new posts on the horizon. For the summer, I am planning a series of 4 articles for the New England Aquarium’s guest blog, and I will link to each of them here. Several other penguin researchers are guest blogging as well. Right now, you can read about Dr. Jessica Kemper’s adventures deploying GPS loggers on African Penguins.
April 25th is World Penguin Day (not to be confused with Penguin Awareness Day, which is January 20th). I celebrated a bit early by sharing the story of our African penguin research at Sigma Xi headquarters. You can see a podcast reviewing the story at the American Scientist website.
In a recent article in PLoS ONE, and colleagues announced the discovery of a new fossil penguin species, Eudyptes calauina. This new species hails from the Horcon locality, along the southern coast of Chile. The fossils are from the Late Pliocene, about 2-3 million years old. Flipper and leg bones were discovered, several of them in very nice condition. The authors completed a phylogenetic analysis, designed to use characteristics of the bones to place the new species within the evolutionary tree of penguins. The results show the new species belongs to the crested penguin genus Eudyptes, which is represented by seven living species (eight if you split the Rockhoppers more finely). These penguins are defined by their bright yellow head plumes, which are present in both males and females. Interestingly, there are no crested penguins in the region today. Banded Spheniscus penguins dominate, including Magellanic Penguins (Spheniscus magellanicus) and also a few Humboldt Penguins (Spheniscus humboldti), which have their main strongholds to the north. Besides extending the geographic range of the Eudyptes group, the new species is larger than any of the living species. Together with previous discoveries of stiff-tailed Pygoscelis penguin fossils in Chile, fossil excavations are revealing a major turnover in penguin faunas along the coats of South America within just the past few million years. Given that penguins have been hanging out on the continent for over 40 million years, this can be viewed as a rapid change.
One of the reasons this new discovery is important is that it tells us more about the relationship between ocean currents and seabird faunas. The Humboldt Current plays a major role in defining ecosystems along the Pacific coast of South America by providing nutrient rich cold-water upwelling. Today, the seabird communities of northern Chile and Peru are quite distinct from those in southern Chile, with a general trend towards more cold-adapted birds taking over as one moves south. We know a lot about the history of penguins in the northern part of Chile and Peru from fossils such as the “bobble-headed” penguin Spheniscus megaramphus, which lived around the same time as Eudyptes calauina, as well as much older fossils like Perudyptes devriesi. However, up until now we have had a very poor understanding of what types of penguins where living in the southern Pacific coastal area. Eudyptes calauina heralds a pattern differences that many paleontologists suspect will grow more profound as more field work is conducted, reinforcing the role of ocean currents in enforcing boundaries between species assemblages.
Chávez Hoffmeister M, Carrillo Briceño JD, Nielsen SN (2014) The Evolution of Seabirds in the Humboldt Current: New Clues from the Pliocene of Central Chile. PLoS ONE 9(3): e90043. doi:10.1371/journal.pone.0090043
Today is Penguin Awareness Day, and what better way to celebrate than recapping a visit to some great penguins (and their awesome keepers). Recently I ventured out Jenkinson’s Aquarium in New Jersey. While interacting with penguins is always worthwhile, this trip is tied to a research project aiming to get better estimates of the sizes of extinct penguin species. Paleontologists have long been aware of “giant” penguins in the fossil record, but the estimates for their sizes have fluctuated wildly. Old sources proposed that some species were up to six feet tall, which we now know is a gross overestimate. The tricky part is that some fossil penguins had very different skeletal proportions than modern species, so it is not safe to just “scale up” any one bone. For example, we know from nearly complete skeletons of Kairuku that the humerus was longer compared to the rest of the body than in modern penguins, whereas the coracoid was shorter. If we tried to guess the height from just the humerus, we’d end up with a bird roughly five feet tall, versus a height of just over three feet if we instead scaled up the coracoid bone. The truth lies in between – reassembling the skeleton suggests the extinct penguin’s height was about four feet and two inches in “normal” pose.
At the aquarium, two fine birds named Dunlop and Kringle offered some perspective. These two are part of the aquarium’s colony of Black-footed Penguins (Spheniscus demersus). With the help of penguin manager Reagan Quarg, I collected measurements of their standing heights. With these measurements (and many more from other penguins), we hope to calculate the range of variation in extant species. One thing we have emphasized is that there is no single standing pose for penguins. Depending on their mood and the temperature, penguins may stand tall with their neck mostly extended, or hunch down like a grumpy child. The penguins at the aquarium showed quite a range of heights. Dunlop measures about 20 inches to the top of his head (not counting the beak) when reaching for a treat but only about a foot tall when hunched over.
In the northern hemisphere, winter is in full swing and snow has begun to accumulate in many cities. If you think braving the icy wind to get your driveway cleared of snow is a challenge, consider the struggles of the Emperor Penguin. Emperor Penguins not only survive the Antarctic winter, during which temperatures drop well below freezing and winds whip to gale-force speeds, but manage to complete their breeding cycle in this incredibly harsh environment. The amazing abilities of these birds to survive extreme conditions has been well documented by scientists and filmmakers. Nevertheless, there is still more to learn. A recent study by Dr.Dominic McCafferty of the University of Glasgow and colleagues in France showed that Emperor Penguins actually drop their surface temperatures below air temperature and get a sneaky benefit from doing so.
Penguins need to stay warm to survive, and also to incubate their eggs and warm their hatchlings. Thus, their core body temperature stays at about 37C (about 98F), in part due to their system of counter-current heat exchangers. While the core stays warm, however, temperatures at the extremities can plunge – in effect the penguins “turn off” heat flow to the flippers and feet to minimize overall heat loss. In the study, researchers used infrared imaging to measure the temperature of penguins in a breeding colony and find out how different parts of the body surface varied in temperature. During the measurements, air temperatures were a bone-numbing -17.6C (0 F). Unsurprisingly, the warmest parts of the penguins in these images were the eye and beak region and the flipper, which are two regions that are not wrapped in thick blubber (or lined with feathers, in the case of the beak). The rest of the body offered a surprise though – much of the penguin’s surface dropped below the ambient air temperature! In fact, many regions reached levels below freezing. The team concluded that this paradox may serve a useful purpose. Penguins are constantly losing heat through radiative heat transfer because their core temperature is so much higher than the surrounding temperature. They slow this process through the insulating effects of blubber and feathers, and by huddling with other penguins, and also burn the fuel of stored fat to generate metabolic heat. Heat can also be transferred by convection, and this is where the sub-zero plumage comes into play. Heat can be harvested by convection from any air that is warmer than the plumage. As the Antarctic air swirls around, packets of air that are above the plumage temperature will sometimes come in contact with the penguin and in these cases the features can absorb a bit of the difference. The amount of heat gained by this phenonomen appears to be very small, but in extreme environments every bit helps.
McCafferty DJ, Gilbert C, Thierry AM, Currie J, Le Maho Y, Ancel A. 2013. Emperor penguin body surfaces cool below air temperature. Biology Letters 9: 20121192.