29 October, 2003

Last night we had about 7-8 cm of snow in an amazingly windless storm. We'd seen clouds building to the north all day, and they enveloped us late in the evening. Our view of Mt. Erebus disappeared and a light snow began to fall. By morning the storm had passed, as silently as it had approached. The sun shone across the new snow and it was time to set off in search of seal pups. Kelly and I went to Tent Island, while Gillian and Mark started at Little Razorback planning to circle around via Inaccessible Island to meet us somewhere in the middle.

There were very few female seals and pups at Tent Island. Instead, Tent Island seems to have become the new hangout for male seals. Specifically, today it was the hangout for untagged male seals. This was to be a day to practice and refine our seal-bagging skills. We had ample opportunity to try out a variety of methods, ranging from the simple 'toss and bag' to the 'chase and tire them out and then bag' method. By the end of the day, our two groups had bagged and tagged 21 males and 21 pups. As of today, we have tagged 137 pups. This is fewer than last year's numbers, but about the same as 2 years ago.

One note-as we were wandering amongst the Weddells there was one seal that looked and sounded different from the others. It was a Crabeater Seal. Even its teeth were noticeably different from the Weddells'-their teeth have grooves on them. They are filter feeders, sucking in seawater and straining out the krill with their teeth. These seals usually inhabit the pack ice, but this one seems to have found a good spot at Tent Island.

This is a good time to introduce another member of the Weddell Seal team, Darren Ireland. When asked about his role in the project, and life in general, Darren wrote this:

Growing up in southwest Montana I was introduced to the outdoors at an early age. Skiing, hiking, camping, and other outdoor pursuits have been a part of my life since I was learning to walk. Through this exposure to the natural environment and working in Yellowstone during summers in high school, I decided to study biology in college. I was lucky enough to volunteer and then work for the Bear Management Office in Yellowstone where I was first introduced to ecological research and species management. Attempting to understand interactions between animals, their environment, and how humans figure into the mix was a very interesting challenge and convinced me that I would like to continue studying ecology. At about that time the opening for this project was announced and before I knew it I was heading to Antarctica for my first field season.

As you may have figured out from what Susy has already written, my part of this project involves developing a method for estimating the mass of Weddell seals using digital photographs. The seals are very heavy and therefore difficult to weigh without significant investment of time and risk to the seals and researchers alike. If we can figure out a way to accurately estimate each animal's mass from a photograph or two, then we can obtain a much larger sample size than previously possible with fewer disturbances to the animals. The larger sample of individual weights from animals within the population can provide insights into the direct effects of environmental changes on this population of Weddell seals.

In order to build a predictive equation that will estimate an animal's mass using measurements taken from a photograph I need to take photographs of animals with known weights. To do this I walk through the seal colony near our camp and take digital images from two angles with the seals in specific body positions (laying on there side like they usually do). In order to compare measurements between photographs I must also hold a scale bar in the image so I can make accurate measurements. Once the appropriate photographs have been taken of each seal I then attempt to weigh them. This is quite an interesting process and I believe Susy has already described it and provided photos. When I get back to the lab I take measurements from the photographs using special software and compare those to the weight of the animals at time of photography, if we managed to get the animal on the scale.

With the predictive equations (one for pups and one for adults) finalized at the end of this season, animals will no longer need to be weighed and all we will need to do is walk up and take a couple photographs of a seal and we will know how much it weighs, give or take a few kilograms.

In addition to working on his Master's Thesis, Darren has filled a very important niche in our camp life as official 'grillmeister' in charge of the southernmost propane grill in the world

Daily Haiku:

Adult males abound

Lounging about on the ice

Do any have tags?

Darren Ireland tagging a seal

The storm moves in from the north.

The Weddell Seals leave trails in the new snow as the move across the ice.

This is a crabeater seal. Compare it to some of the earlier pictures of Weddell Seals to see differences in coloration and the shape of its head.