Weekly Report: March 11-17
The past week has been one of landmarks. We passed the halfway point of the cruise (28 days), and left the western Ross Sea for the eastern Ross Sea.
On Tuesday, March 12, we sighted the first large group of emperor penguins. As we sailed further east emperor penguins became notably more numerous. It is likely that we were passing through the first wave of penguins that live in colonies of the western Ross Sea and were migrating back from areas where they molt in the eastern Ross Sea.
We celebrated March 14 twice after crossing the International Date Line. On the first 14th, we arrived at Cape Colbeck. After seeing a few groups of emperor penguins at the ice edge and in the water, we decided to dock the RV Palmer at the fast-ice edge a few miles into Bartlett Inlet. A large colony of emperor penguins breeds here during the Antarctic winter months and we hope the birds present now are a contingent of that group. Presumably those here now have arrived early and continue to feed avidly in preparation for the long winter fast that will begin in April.
Soon after dinner we debarked from the ship and, with snowmobiles, drove to a group of birds at the fast-ice edge about a half-mile from the RV Palmer. We approached some birds that seemed to be settling in for the night. Over a span of a few hours we attached satellite tags to six birds that will transmit location and behavioral data over the next few months.
On the second 14th day of March, we captured and attached satellite tags to birds in the morning and afternoon. In total we attached 10 more tags for the day and considered it a super successful campaign. This is especially so because emperor penguins have never been studied during the time of year between the molt (February) and the start of breeding in April. Scientists are missing information about this important segment in their annual cycle (learn more: About the Science).
The following day—while everyone on the ship enjoyed a penguin parade as emperor penguins came and went from the ice edge next to the ship—eight of our research team took snowmobiles to the deserted colony. Although completely abandoned for the year, and totally buried under a meter of snow, some coring into the snow confirmed by sight and smell that we were on the colony.
The location closely matched coordinates from previous aerial surveys. Unfortunately due to the snow cover, it was not possible to make any assessment of the previous year’s breeding success based on the number of lost eggs and dead chicks. We returned to the ship and that evening left Cape Colbeck to resume our search for emperor penguins in the pack ice west of the Cape.
On March 16, while turning back from our western course because of heavy pack ice, we deployed two tags on penguins resting on a large floe with two other birds. All around us most of the floes were occupied with resting birds, presumably settling down for the night, but we decided to continue further into the pack ice to deploy the last satellite tags. In the afternoon of March 17 we came across two emperor penguins in some thin ice and deployed the last satellite tags.
The past week has been most enjoyable for the penguin group, with the icebreaker available to us for several days. In the course of that period, we have deployed a total of 20 tags in addition to the one attached to an emperor penguin in the western Ross Sea. All the satellite tags are transmitting location and diving behavior data, which we will analyze at our home institutions in order to improve our understanding of the foraging behavior of emperor penguins during this important time of year.