Just yesterday while I was assisting the divers off of Hermit Island a “flock” of Adélie Penguins (Pygoscelis adeliae for you scientific aficionados) erupted from the sea just a few feet from our zodiac’s bow with a most impressive display of “porpoising” behavior. This swimming technique allows them to make full use of their paddle-like wings, rhythmically launching themselves above and below the surface of the sea. As intermittent air is less of a barrier to penetrate than solid sea, this approach to travel boosts their speed considerably. Those competing in the butterfly stroke at the upcoming summer Olympics in Athens should take note!
Arriving in late October or early November, the Adélie Penguins spend their first days collecting stones to build their nests and go through their courtship behaviors. I will never forget my first visit to an Adélie Penguin rookery many years ago at Cape Royds, north of McMurdo Station on the Ross Sea. I arrived just in time for nest building and witnessed hundreds of nervous soon-to-be parent penguins comically stealing the stones from the nests of their neighbors to build for their own nests. I sat on the hillside and chuckled at this Charlie Chaplinesque scene below me.
By mid-November two eggs are laid and mom and dad take turns incubating these eggs for about 30-45 days until they hatch. Once hatched, the penguin chicks require the full attention of both parents, both for food and protection. A visit I made to nearby Torgersen Island a little over two years ago brought this home to me. Sitting upon strategically located rock perches all around the noisy penguin colony were Skuas, large predatory birds intent on swooping in and grabbing an unsuspecting chick. Parents had to be vigilant! After 41-64 days the young birds fledge (take on their adult feathers) and by mid-February they are at sea. This is good timing as their favorite food, krill (little shrimp-like animals), are often abundant at this time. The adult penguins are capable of diving to depths of up to 575 feet to feed, but likely they spend most of their time feeding in surface waters.
Adélie Penguins have a broad circumpolar distribution. This means that they can found all around the continent of Antarctica and have a population numbering about 2.5 million breeding pairs. Interestingly, their population numbers have decreased here on the Antarctic Peninsula, but simultaneously increased around the Ross Sea. Several years ago noted penguin biologist, Bill Frazier, told me that he thinks that increased snow fall here on the Antarctic Peninsula is contributing to this trend. With global warming causing temperatures to increase it now snows more here on the Peninsula than in years past (warmer air holds more moisture and thus increases snow fall). Nesting Adélie Penguins can be buried under the snow causing egg mortality.
No matter how many times I find myself offshore in a small boat or hiking the shoreline near Palmer Station, when I come upon Adélie Penguins (or they me), I delight in their “little man in evening dress” appearance and their graceful movements. They are after all, other than the Emperor Penguin, the only other truly “Antarctic” penguin. I know then that I am indeed in Antarctica and amongst its finest of denizens.