Feeding on a diet of tiny marine crustaceans, the little auk obtains is food by diving to depths of up to 35 metres, before using its natural buoyancy to swim upwards in a zig-zag pattern and capture its prey. This allows its prey to be backlit against the surface light, and the prey items are then caught in the little auk’s small, wide bill (3). The little auk often feeds at night, when its prey migrates to the water surface. In some parts of its range molluscs and small fish are preferred prey and are captured after a short, rapid pursuit through aquatic vegetation (3) (8). Breeding birds typically forage within 10 to 100 kilometres of colonies along ice edges, but at other times of the year the little auk floats passively on strong ocean currents, often with sustained flightless periods, feeding far out at sea (3). The little auk is the only auk species with a specialised, extensible pouch in the throat which is used to carry prey to nestlings (3).
A highly gregarious species, the little auk breeds in huge, dense colonies, which comprise more birds than any other auk colony, with the timing of breeding varying across the species’ range (3) (7). Prior to the onset of breeding, massive, noisy flocks of birds gather on the water near to the colony, before flying in wide circles while emitting loud calls and gradually making their way to land. Competition for favourable nesting sites is fierce and can lead to fights between birds, with dominant birds chasing opponents in the air. Once a nest site is obtained, it is defended with territorial displays of head-bowing and upright walking with the back arched and the bill pointed upwards (3). The nest is a simple bed of pebbles in a sheltered crevice amongst a field of boulders, and the single egg is incubated for around 29 days by both the male and female (2) (8). The chick fledges after 27 to 30 days, after which it becomes fully independent and flies out to sea alone (2).
Once the colonies are abandoned at the end of August, the little auk undertakes lengthy southward migrations. Typically it stays far out at sea, but after strong storms, weakened, starving birds are quite often pushed landwards and turn up in areas where they are not normally found (2) (3). One such notable occasion was in the winter of 1932-1933, when huge numbers of little auks washed up along the entire eastern coast of North America, with birds even being found on the streets of New York (8).