Saturday, June 27, 2015

Arctic Tern - A Life of Ice, Light and Flight

On the afternoon of January 12, 2015 I was immersed in a surreal setting of ice, snow and water. We were just west of Booth Island and north of Pleneau Island on the Graham Coast of the Antarctic Peninsula. Above me in the clouds to the east were Mt Shackleton and Mt. Scott, but I had to trust the map to tell me that. There were no mountains to be seen that day. The clouds were low and large flakes of snow floated from the what was left of the sky, seemingly spontaneously forming just above our heads.

We were there because of the icebergs. This area is a frequent stop of tour ships because the currents and islands conspire to push icebergs into this area where they slowly decay into constantly changing abstract sculptures.
The day had started out with a curious Minke Whale checking out our Zodiacs as the staff prepared to transport guests to Peterman Island where we were able to visit colonies of breeding Gentoo and Adelie Penguins with a few Blue-eyed Shag nests in the mix.
Sandra and her friend the curious Minke Whale.
The afternoon was spent in the zodiacs, maneuvering through the shifting mountain ranges of icebergs, brash ice, and bergy bits to fully experience a true Antarctic spectacle of ice.

A chunk of bar ice where you can see how the water erodes small cup shaped divots from the ice. Photo by Sandra Petrowitz.
Perhaps just as interesting for me were a number of birds we found perched on the icebergs and feeding in their shallow pools. They were Arctic Terns and there were more of them in one spot than I have ever found on the Antarctic Peninsula. 

They were perched high on the ramparts of towering bergs in an Antarctic version of birds on a wire. 

The migration of this species is quite remarkable. They breed in their namesake region - the Arctic, but then migrate south through the Atlantic Ocean (and probably the Pacific Ocean as well) to spend their non-breeding summer in the Antarctic Pack ice. We know more about the portion of the population the migrates through the Atlantic through some interesting research conducted on Arctic Terns in Greenland and Iceland known as the Arctic Tern Migration Project. Below are a couple of maps that show the migration route and winter areas of the eleven birds they tracked (both images from the Greenland Institute of Natural Resources)

Simplified figure showing migration patterns of the Arctic tern, from the breeding sites in Greenland and Iceland to the winter grounds at Antarctica. After initiating the southbound migration (yellow line) the birds paused their migration in the central part of the North Atlantic (small circle) for almost a month before they continue towards the wintering sites at Antarctica (large circle). In spring, the northbound migration (white line) is conducted more than twice as fast in a gigantic “S” shaped pattern through the Atlantic Ocean. Areas particular rich in biological productivity are indicated by yellow and green colors.

Interpolated geolocation tracks of 11 Arctic terns tracked from breeding colonies in Greenland (n = 10 birds) and Iceland (n = 1 bird). Green = autumn (postbreeding) migration (August–November), red = winter range (December–March), and yellow = spring (return) migration (April–May). Two southbound migration routes were adopted in the South Atlantic, either (A) West African coast (n = 7 birds) or (B) Brazilian coast. Dotted lines link locations during the equinoxes.

As you can see from the map above, the wintering area for most of these birds is the edge of the pack ice in the northern part of the Weddell Sea. Presumably they spend their non-breeding summer much like I observed them - foraging among the ice in the open waters between the ice as well as the shallow waters formed by the icebergs themselves.

One iceberg in particular formed a spectacular eroded backstop for the foraging terns. 

There were a few other creatures foraging in the same area with the terns. We observed another less inquisitive Minke Whale that afternoon as well as a Crabeater Seal lounging in an iceberg pool and a few Kelp Gulls. 

So why did I see so many on this trip? One explanation is that I just hadn't been in the right place at the right time and they have always wintered in this area. However, I believe that this year the pack ice was so heavy in the Weddell Sea that there was essentially no open water and the birds wound up concentrating along the Antarctic Peninsula in numbers that would not be found during a "normal" year just to be able to find something to eat. 

Perhaps a more fitting name for this bird would be the Polar Tern, since they spend a majority of their life in both polar areas where they also experience perpetual daylight. The distances these birds migrate is impressive and when they are not breeding or wintering in the polar regions they are flying in a twisted migration loop back and forth across the Atlantic Ocean. 

Thursday, May 21, 2015


I have been struggling to find time to complete more blog posts about my journey to Antarctica, the Falklands, and South Georgia, but I have also struggled with developing a non-linear framework to build stories of my trip around. I really don't want a regurgitation of a daily log book - we went here and we saw this, lather, rinse, repeat. Fortunately, International Penguin Day was earlier this month and although I am late with this post, it provided a seed for me to get started with a series of posts about my travels and the places I visited.

Zodica cruise - Saint Andrews Bay, South Georgia 1/24/15
Last night I pondered over the justification most people use to explain their travel to Antarctica and I came up with four main reasons (this is only for those on leisure travel to Antarctica, musings about those who travel to work in Antarctica would require a completely different discussion). The reasons I came up with are, in no particular order: to experience wild penguins, to visit the only continent they haven't been to, to connect with the place where Antarctic history occurred, and...polar bears (a tongue-in-cheek reason used to describe the people who really don't know where they are going, but the brochure looked really nice). Although "penguins" is a rather specific reason for a visit to Antarctica, the label can be used to represent the desire to observe Antarctic wildlife in general, but because penguins are the most obvious and unique representative of this relatively wild place, they get the label. Most of my subsequent posts can be categorized under "penguins" when we consider it more broadly to include the wildlife of Antarctica, but I will also touch on Antarctic history here and there. I probably won't venture into the realm of "last continent to visit" themes and I am certainly not going to touch the "polar bears".

I am going to stick specifically penguins today. There is plenty of information concerning penguins available from other sources, including very good new book Penguins: The Ultimate Guide (which I will review in greater detail in a future post), so I am not going to delve into details and facts on this post and I will stick to photos of the species we observed.

Many travelers to Antarctica come to specifically see penguins and this trip was good for those travelers.

The first species I am going to present is the Adelie Penguin. This is the species I previously worked with the most and I have a soft spot for these tough little creatures. Unfortunately we did not see many Adelies on this trip. They are declining rapidly on the Antarctic Peninsula and the only place we were able to observe them at a breeding colony was on Peterman Island, where a few pair still manage to hang on. We did find quite a few groups along the heavy pack ice edge in the Weddell Sea however. The Weddell was stuffed full of pack ice this last summer - more than I have ever observed and the ice loving Adelies were common along the ice edge.

Adelie Penguins - Weddell Sea

We were able to observe a number of Chinstrap Penguins on this trip. We visited breeding colonies on South Georgia and on the South Shetland Islands and also observed a number of individuals at scattered locations on the Antarctic Peninsula.

Gentoo Penguins are now the most common penguin encountered on cruises to the Antarctic Peninsula and we visited a number of colonies there, as well as in the Falkland Islands. In fact, unless all you want to see are Gentoos, it would be a benefit to pay attention to the detailed itinerary for your trip to Antarctica. Some agendas result in only visits to places where only Gentoos are found. 

One of the high points for me was the chance to visit the King Penguin colonies on South Georgia again. We visited a number of locations in South Georgia where they breed and I  enjoyed seeing them again. Unfortunately we were unable to visit the main part of the colony at Saint Andrews Bay this year because the glacial meltwater stream that we need to cross was flowing way to heavy and fast to get across. The high flows were due to the very warm temperatures we experienced for a couple of days leading up to our stop there. 

Many of the birds were going through their annual molt, while others looked just fine. 

We did find one lone Emperor Penguin too. As I noted above, the pack ice in the Weddell Sea was extraordinary this year so we were only able to cruise along the edge of the pack just east of the peninsula. As we were cruising along the edge the Captain exclaimed that he had found an Emperor just ahead. I was doubtful as was our other main naturalist aboard the ship because the bird in question just did not look big enough for an Emperor. Even when we got close it just didn't look right to us. However, once we were able to get better looks and zoom in on our photos we realized that it was indeed an Emperor - just a very young one that wasn't even close to adult size. Still an Emperor Penguin though and the Captain was right once again. 

We had a great afternoon with Macaroni Penguins at one of our stops on South Georgia near Cooper Bay. There are a couple of colonies of Macs here and we were able to get wonderful views of these birds from the Zodiacs. 

We observed quite a few Magellanic Penguins in the Beagle Channel every time we transited in or out of the channel. On our first stop in the Falkland Islands on Saunders Island, there were a few birds near a Rockhopper Penguin colony where we were able to observe them up close on land. 

We also got to see a couple of colonies of Rockhopper Penguins at Saunders Island. 

The photo above shows the grooves that have been worn into the rocks by generations of Rockhoppers digging in with their claws as they slide down these slopes.