General Overview
The Alcidae family, commonly known as auks, includes puffins, murres, guillemots, auklets, and related seabirds. There are about 25 recognized species, all confined to the Northern Hemisphere. Alcids are highly adapted for life at sea, where they spend most of their lives, coming ashore only to breed. They are excellent divers and swimmers, using their wings to “fly” underwater in pursuit of fish and other prey.
Appearance
Alcids are medium-sized seabirds with compact, stocky bodies, short tails, and relatively small wings. Their plumage is typically black, gray, and white, often with sharp contrasts that aid in camouflage at sea. Puffins are among the most distinctive, with brightly colored bills and feet during the breeding season. Murres and guillemots are sleeker, with sharp bills adapted for catching fish. Seasonal changes in plumage are common, with brighter, more striking patterns during the breeding season and duller, cryptic plumage in winter.
Diet
Alcids are carnivorous, feeding primarily on fish, squid, and crustaceans. They hunt by diving underwater, using their wings to propel themselves with remarkable speed and agility. Puffins, for example, can carry multiple fish crosswise in their bills at once, aided by spiny tongues and specialized palates. Diet composition varies by species and local prey availability but is almost always marine-based.
Habitat
Alcids are strictly marine birds, spending most of their time on the open ocean. They breed on coastal cliffs, rocky islands, or in burrows on remote shorelines, often forming dense colonies. Outside of the breeding season, they are highly pelagic, ranging widely across the northern oceans. Their distribution is centered in the North Atlantic and North Pacific, with different genera dominating each region.
Behavior
Alcids are strong divers but relatively poor fliers compared to other seabirds, with fast, shallow wingbeats required to stay airborne due to their high wing-loading. They are colonial breeders, often nesting in large, noisy groups that provide protection against predators. Nests may be simple scrapes on ledges or burrows dug into soil. Parents share incubation and chick-rearing duties, with some species carrying fish back to chicks one at a time while others feed them by regurgitation. Social at sea as well, alcids are often seen in groups, diving and foraging together. Many species migrate seasonally, though movements are poorly understood in some populations.
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