Do you know which flying bird holds the record for the deepest dive? What about the bird that holds the record for the heaviest body compared with the size of its wings (which is a good indicator for how clumsy a bird is when it flies)? Any clues? And the bird that lives in the most densely populated colonies of the Arctic. Do you know that one? It turns out all these records are held by the same bird: The Thick-billed murre, known locally as akpa in the North.
Although unknown apart from the hunters who seek them for their delicious meat, the akpa is nevertheless the most common seabird in the Arctic. Akpas are however hard to see, as they spend winter far from shore, in ice-free water. They come back on land during the summer to breed, where they gather in colonies of up to one million individuals. These loud and dense aggregations are, however, often located far from settlements, on hard-to-reach island cliffs. Those colonies close to settlements, such as the Digges Island colony near Ivujivik, Nunavik, are great spectacles that spark the imagination of any visitor.
As this bird spends most of its time at sea, one wouldn’t be surprised to know that it feeds on fish. But this bird is more determined than others, often diving more than a hundred metres deep and staying up to six minutes underwater to capture prey. One bird was recorded going as deep as 180m, a record for a flying bird, as only the flightless penguins go deeper. Its diving prowess has a cost however. The optimal shape of a wing for diving is short and broad, for better manoeuvrability, quite the opposite of what you would expect from a wing efficient for flying. Result: the akpa can fly, but movements like taking off or changing direction are quite tricky to accomplish. Its heavy body doesn’t help either, making the akpa the flying bird with the highest “mass/surface of the wing” ratio.
Lack of agility in flight is not a big problem for this bird however, as very few predators attack adults, so there is no need for a quick escape. The main cases of predation happen rather during their early stage of life. On the cliff, during the breeding season, eggs and chicks are often sought by gulls and foxes. Climate change has brought an even more voracious predator, the polar bear! Polar bears usually do not wander around bird colonies during the summer, as the seals they hunt on the ice sheet during late spring are normally enough for them to survive the whole summer without eating. With climate change however, the sea ice is melting faster, allowing less time for polar bears to stack up reserves. Bird colonies suddenly look like giant buffets, and what used to be a risky undertaking is now worth a try. A polar bear is much more gluttonous than a gull or a fox, eating hundreds of nests at a time and clearing whole ledges from akpa occupation. Fortunately, these birds are long-lived birds (up to 36 years old), and adults that lose their nest to predation will have plenty of opportunities to breed again in the following years.
There is still much to know about this fascinating bird, and research is ongoing to learn more about its lifestyle, which have been studied by Inuit hunters for eons. Its diving abilities, position in the marine ecosystem as a top predator, and abundance makes it a great scientific model for studies all around the Arctic. Who knows, we might discover another record to add to its already impressive collection.