December 20, 2016
I woke up to surprisingly calm seas in the Drake Passage. These conditions represent what is called the “Drake Lake” – almost surreally tranquil seas. Most of the staff of the ship has been indicating that this is the most placid they have ever seen these waters. While it’s difficult to remember today, this Passage constitutes one of the roughest stretches of sea in the world, as there are no masses of land at this latitude to block prevailing currents. This Passage, accordingly, represents a great spot to study allopatric speciation; I am very concerned with how the type and variety of organisms will change as we cross, so it was up to the bridge at 5 AM to look for as many signs of life as possible.
The type of life in the open waters of the Drake is distinctly different from that observed in the Beagle Channel. Most of the birds here are pelagic, meaning that they spend most of their lives on the open ocean. The shags, terns, geese, and gulls that I saw in the Beagle were no longer present, being replaced by birds collectively known as tubenoses. All occupying the order Procellariiformes, there are four distinct families of tubenoses – albatrosses, petrels and shearwaters, storm petrels, and diving petrels. The namesake of these birds is the tubular external nasal passage, allowing for a much better ability to smell (Lequette, et al., 1989). Many other unique adaptations allow these birds to live in the open water. Notably, albatrosses and giant petrels both have a tendon which serves to lock the wings in the fully extended position, granting increased wing stability in windy conditions (Pennycuick, 1982). These birds progress soar above the open ocean at incredibly vast speeds, yet they seem to do so almost effortlessly, with very few wing beats. Members of the order Procellariiformes are also all adapted to be able to drink sea water, getting rid of the salt taken in through special glands on the bill (Ehrlich, et al., 1988). Storm petrels were especially interesting to watch dancing in and out of the waves. Often referred to as “sea swallows,” these tiny birds have developed a flight feeding technique called surface pattering, in which they seemingly walk on the water to grant increased stability and allow for travel at a decreased speed. This aids them in the search for food (Henderson, 2008).
In addition to the Black-browed Albatross and Southern Giant Petrel (encountered yesterday), I encountered three new species of albatross – Wandering Albatross, Southern Royal Albatross, and Northern Royal Albatross – as well as the Northern Giant Petrel, Blue Petrel, White-Chinned Petrel, and Wilson’s Storm Petrel. A special highlight around midday was a raft of Southern Rockhopper Penguins, my first penguins of this expedition! I was amazed at how far from land these penguins were observed – well into the open ocean of the Drake Passage. Around this same time, we also saw a pod of Hourglass Dolphins porpoising through the calm sea.
Later in the day, I got to meet two more naturalists aboard the Explorer – Pete Puleston (naturalist from the USA, who has been traveling on expeditions to the Antarctic since 1978) and Dr. Conor Ryan (naturalist from the UK, specializing in whales). I am very thankful to them both for the time they spent with me on the bridge helping me identify birds and other wildlife.
As I was exiting the bridge, the captain told me that overnight, we will be crossing the Antarctic Convergence. As I noted in my first post, this zone represents the merger of the cold, north-flowing Antarctic waters with the warmer sub-Antarctic waters. The cold waters drop beneath the warmer waters here, resulting in an upwelling of nutrients, upon which an entire food chain of organisms is dependent. Tomorrow, we will be in truly Antarctic waters, and I look forward to observing the resulting changes in the observable wildlife.
Grosvenor Teacher Fellow
National Geographic Society