Update #6
26 Jan. 2005
Our research at Mario Zuchelli station has been much more productive than what we've been able to accomplish in the previous weeks. The weather has remained nice for most of our visit and the efficient helicopter operations have facilitated our progress. Our first field outing was to Inexpressible Island located about 20 kilometers south of the station. Located at the base of two major glaciers, it's usually quite cold and windy here. On the day of our visit, 23 Jan., it was still very cold, but the winds were relatively light so we stayed the full day to complete our work. We were dropped off on terraces above an active Adélie Penguin colony, much larger than the one at Edmonson Point, and located some abandoned sites on a ridge high above the modern beach. These former colonies appeared quite old from the amount on lichen covering the pebbles on the surface of the ground. Previous dates from our work in this area last year indicated an age of 3000 - 3500 years for these sites.
We excavated a 1x1 m square in one of these abandoned sites and found the penguin sediments to go fairly deep, to at least 30 cm, before encountering beach sands and gravels below. All levels of the site contained abundant eggshell remains, plus small pieces of bone and feather. From this evidence, we will be able to obtain additional radiocarbon dates and more information on the occupation history of this island by Adélie Penguins.
After backfilling this pit and taking a break for lunch, we set out to visit the site where a group of early explorers had built a snow cave and spent the winter of 1912 here while waiting to be picked up by their ship. They were not expecting to be stranded here back then, but when their ship didn't arrive at the end of the summer, they had to dig in and survive the long Antarctic winter. They killed some Weddell Seals and Emperor Penguins for food and stockpiled these animals for use throughout the winter months. All that is left of their campsite are bones of these animals scattered about on the ground. A sign currently marks the spot where their snow cave had been.
Last year, near this campsite and on the beach below, we had found mummified carcasses of several Southern Elephant Seals. Thinking that these also were animals killed by the 1912 group for food, we found since then that records left by this group gave no mention of this species in the area. So, the mummified remains were from some other event. The carcasses also were unusual in that this species rarely ventures into the Ross Sea today. What did their presence here in the past, and in so many numbers, signify? Could the climate have been more favorable for an expansion of this seal into the Ross Sea at some time in the past? And, if so, why did they all die on this beach at seemingly the same time? We set out this year to document these carcasses in more detail to help answer these questions.
Our first objective was to locate, measure, and photograph each carcass. We systematically searched the beach area where we had found three carcasses last year. For each one encountered, we recorded the amount of carcass still left, took measurements of the skull, teeth, and body length when possible, took numerous photos, and then recorded its GPS position and elevation above sea level. We also noted its position, either belly down or belly up. After completing this survey, we had a total of nine carcasses located. Most of these were complete and represented medium to large-sized males (the females do not get as big as the males). Most also were lying belly down when they died and all exhibited about the same level of mummification and weathering--the backs and tops of the skulls were scoured away by constant Antarctic winds. So, my tentative conclusion is that all animals died at the same time. It may have been a group of males hauled out on the beach to molt. If they were not killed by people for food, which seems to be the case, then perhaps they all died in a sudden blizzard that buried them in snow. We may never be able to determine the answer to that question.
We had one last surprise before leaving Inexpressible Island at the end of the day. I saw a penguin come onto the beach about 200 m away from where we were working on the seal carcasses. Normally, this would not draw my attention, but the way this penguin was walking with a waddling gait, made me realize that it was not an Adélie Penguin. The only other species it could be here is an Emperor Penguin! This species does not come ashore very often so seeing one here was a special treat. We approached the bird carefully and kept our distance, and we were able to get good photos of it. It did not have adult markings and represented a subadult. It was a nice way to end our visit to this island.
The day after this trip, we visited Edmonson Point again and collected more samples from abandoned colonies here. Then, the next day (25 Jan.), we were informed that there were clear skies over Cape Adare, a small cape that juts out from the mouth of the Ross Sea, and that this would be a good day to try to reach this remote spot. I've been interested in visiting Cape Adare for several years. First, it is the largest Adélie Penguin colony in Antarctica with over 150,000 nests, and perhaps as many as 200,000, nests of this species. With a pair of birds at each nest, plus their one or two chicks, that meant a visit to this colony would treat us to a view of approximately a half million birds! I was also interested in obtaining samples here to see just how old this colony is. I once thought that it might be the oldest active colony in Antarctica, given it's size and location near the continental shelf (meaning close open water here, even in years of heavy sea ice). However, photos I had seen of the colony indicated it was situated on a large, flat beach that has probably been above sea level for only a relatively short time (1000-2000 years?). Still, I needed samples from here to test this idea and Cape Adare is very difficult to reach--it is far from all the stations so flights take a long time to get here, plus the tip of the cape is almost always covered in fog, preventing helicopters from landing there. We had tried unsuccessfully last year to reach this colony. Today, though, our luck changed.
We flew by helicopter from the station for over 1.5 hrs to the north, then stopped at a fuel depot near Cape Hallett to refuel. From there, we flew another 40 minutes and, while clouds were covering part of the cape, we could see clear routes below and for the first time I saw this large colony from the air. Our able pilot, Angus, got us down safely and we landed on the beach not far from an historic hut where the first person to overwinter in Antarctica, a Norwegian named Borchgrevink, had lived in 1899. The hut was now preserved by an outer shell built over it by the Antarctic Heritage Trust. We had permission to look inside this hut if we made it to Adare, so we had a brief look before starting work on the colony. Artifacts from the expedition remained inside, as well as an old table, chairs, and a rusted out stove. There were bunks for at least seven people and some shoes, boots and miscellaneous clothing still remained as well.
Outside, the large penguin colony was overwhelming. Stretching out all over the large flat beach were large artificial mounds of pebbles built up by penguins gathering nesting pebbles over the years. Every suitable area of beach was occupied by these birds and even the cliff face behind the beach had nesting birds on it, some even on top of the cape above the > 50 m high cliff rising steeply off the beach. We wondered how the penguins could climb this cliff, day after day, to feed their chicks. Hoping to get back there to investigate further, we began sampling some of the mounds near the beach front by digging into the base. I wanted to collect organic remains (bones, eggshell) for dating at the bottom of the penguin sediments in several of these mounds. We were on our third mound, however, when Angus called us on the radio and said we should leave--clouds were starting to creep down the mountain side and if they went much lower, we would not be able to safely fly off the cape and would be stuck for the night, or longer. So, we packed up and left after less than 2 hrs here. Still, it was worth the visit and perhaps in the last few days we have at the Italian station we'll get another opportunity to visit this interesting location. For now, we spent the day washing our sediment samples from Inexpressible Island and Edmonson Point. This processing will allow us to sort out some of the organic remains here and reduce the weight of the samples before being shipped back to the states for additional study.
