Auks are marine birds belonging to the family Alcidae, found across the Northern Hemisphere. These birds have evolved adaptations to thrive in cold ocean environments, often superficially resembling penguins with their upright posture and black-and-white plumage. While they share some ecological similarities, auks are not closely related to penguins, representing a distinct lineage of specialized seabirds. They are pursuit divers, effectively “flying” underwater using their wings to hunt for food.
Key Physical Features
Auks exhibit a compact and streamlined body design. Their plumage features dark coloration on their upper parts, contrasted with white underparts. This countershading helps them blend into their marine environment, providing camouflage from both above and below the water. Their legs are positioned far back on their bodies, which enhances swimming efficiency and contributes to their characteristic upright stance on land.
Auks possess short, powerful wings that serve a dual function. While most species retain the ability to fly, requiring rapid wing beats to remain airborne, these wings are primarily adapted for underwater propulsion. They maneuver through the water with a “flying” motion, using their wings as flippers. Additionally, their webbed feet provide further assistance with steering and propulsion during dives.
The shape and size of an auk’s beak vary among species, reflecting their specialized feeding habits. Some, like common murres, have long, slender, pointed bills, while others, such as razorbills, feature thick, laterally compressed beaks. Puffins have large, brightly colored bills during the breeding season. These diverse bill structures are adapted for capturing and holding specific types of marine prey.
Life in Their Marine Environment
Auks inhabit the cooler waters of the Northern Hemisphere. They are pelagic birds, spending the majority of their lives at sea and venturing onto land only during the breeding season. Their diet is diverse, consisting primarily of fish, crustaceans, mollusks, and plankton, depending on the species and available prey. For instance, strong-swimming murres target faster schooling fish, while smaller auklets consume slower-moving krill.
These birds are exceptional divers, employing their wings to propel themselves through the water as they pursue prey. Common murres can dive to depths ranging from 30 to 60 meters, with some recorded dives reaching 180 meters. Razorbills can descend up to 120 meters, often swallowing their catch underwater to prevent it from being stolen by other seabirds. Little auks can dive up to 27 meters and utilize a suction-feeding technique to capture tiny copepods.
Auks are colonial breeders. They establish their nests on rocky cliff edges, within rock crevices, or in burrows dug into the earth. Puffins often dig burrows in soil for their nests. Once the breeding season concludes, these birds return to the open ocean.
Notable Members of the Auk Family
Puffins, encompassing the Atlantic Puffin, Horned Puffin, and Tufted Puffin, are known for their distinctive appearance. Often called “sea parrots” or “clowns of the sea,” they are distinguished by their brightly colored, large bills during the breeding season and their stocky build with black upperparts and white underparts. Their specialized beaks allow them to carry multiple small fish, such as sand eels, crosswise to provision their young. Puffins are also skilled divers, using their short wings as flippers to propel themselves underwater, reaching depths of up to 60 meters.
Guillemots, known as murres in North America, include the Common Murre and Thick-billed Murre. These large auks are characterized by their sleek, robust bodies and long, thin, pointed bills, typically displaying black-and-white plumage. Common Murres form dense breeding colonies on cliff faces, where they lay a single pear-shaped egg directly on bare rock; its shape helps it resist rolling off the ledge. They commonly dive to depths of 30-60 meters to pursue schooling fish.
Razorbills are auks primarily found in the Atlantic, identifiable by their blunt, black bill with a distinctive white line. These birds have black-and-white plumage. Razorbills are adept at both flying and diving, capable of descending up to 120 meters deep, propelling themselves with their semi-folded wings. They nest in crevices or on narrow cliff ledges, laying a single egg each breeding season.
The Great Auk, now extinct, was the largest member of the family, standing approximately 75 cm tall and weighing about 5 kilograms. This flightless species inhabited the North Atlantic, breeding on remote islands. Despite its inability to fly, it was an exceptional swimmer and diver, utilizing its wings for underwater propulsion similar to penguins. Its diet consisted of fish like Atlantic menhaden and capelin, along with crustaceans. The Great Auk vanished by 1844, primarily due to human hunting for its meat and feathers.