About Fratercula corniculata (J.F.Naumann, 1821)
Adult horned puffins (Fratercula corniculata) are approximately 20 cm (8 in) tall, weigh around 500 g (18 oz), and have a wingspan of about 58 cm (23 in). The species is monomorphic, meaning males and females have identical plumage coloration. Sexually mature individuals have a small fleshy black "horn" that extends upward from the eye, which gives the species its common name. A dark eyestripe runs backward from the eye toward the back of the head, the cheeks are white, and there is a yellow wattle at the base of the bill. Legs and feet are orange. The horned puffin's bill is larger than the bills of other puffin species, red at the tip and yellow at the base. During the summer breeding season, the outer layer of the bill, called the rhamphotheca, grows larger and turns bright yellow with a dark orange tip. The size and color of this layer helps individuals attract mates. After the breeding season ends in late summer, the bright outer rhamphotheca is shed, the face plumage changes to gray and black, and the legs and feet fade to a pale fleshy color; this non-breeding plumage is called eclipse plumage. The bill also has fluorescent properties that are used to attract partners, and horned puffins can see ultraviolet rays, which allows them to detect this luminescence during courtship. Horned puffin chicks have smoky-gray cheeks, a fine, black triangular beak, and pinkish or greyish feet. Juveniles are smaller than adults when they leave the nest. Young puffins lose their greyish facial markings during their first spring. The beak develops its full shape by one year of age, and continues to grow over time, reaching its brightest coloration when individuals reach sexual maturity at five years old. Horned puffins reach their full adult size and weight by the age of five. The horned puffin is relatively common across its native range. It occurs throughout the northern Pacific Ocean, including the Shumagin Islands of the Bering Sea, the Siberian coast, Kamchatka, Sakhalin, and the Kuril Islands. In North America, it is found along the western coasts of Alaska and British Columbia, Haida Gwaii and the Aleutian Islands. It is also found near the Chukchi Sea, particularly on Wrangel Island. More rarely, individual horned puffins travel as far south as Japan, and the coasts of Oregon and California. The species is not migratory, though it spends the winter far out at sea. Horned puffins live on steep rocky slopes and cliffs. Unlike other puffin species, they dig little to no burrows, and instead prefer to nest and shelter in rock crevices or spaces under rock piles. As of 2023, at least one horned puffin has been observed spending summer months on Smith Island, Washington, in the Salish Sea, alongside the local breeding population of tufted puffins. With assistance from regional commercial whale watching companies, researchers are working to determine if this is a lone individual or a mated pair. If it is a mated pair, this location would be a new breeding site for the species hundreds of miles outside its normal range. Horned puffins reach sexual maturity between five and seven years of age, and breed between May and September. Breeding pairs are monogamous. Courtship begins when a male and female swim alongside each other on the water. The male displays by rising from the water with his neck outstretched, opening and closing his bill while jerking his head. The female responds by holding a hunched posture with her neck tucked in close to the water surface. This is followed by billing, a behavior where mated individuals touch beaks. A small head movement from both partners confirms the pair will mate for life. The male then mounts the female from behind, beating his wings to maintain balance. After approximately 35 seconds of mating, the female dives underwater before resurfacing, and both members of the pair then flap their wings. One week after arriving at the breeding area, pairs select a nesting site, preferring rock crevices. They clear a space and collect grass and feathers to build their nest. Each breeding pair lays only one egg per year. Pairs in the same colony typically lay their eggs around the same time, and rarely does laying extend over more than one week. Sperm storage glands in the female's oviduct aid in sperm selection for fertilization. The egg is oval-shaped, off-white with lavender, gray, and brown markings. Both parents take turns incubating the egg for around 41 days, then spend another 40 days raising the chick. When the chick is ready to fledge, it leaves the nest alone at night, travels to open water, then dives and swims away to begin an independent life. Rising ocean temperatures have increased the reproductive rate of the horned puffin. Adult horned puffins have a generalist diet, feeding on fish, small invertebrates, crustaceans, polychaete worms, and squid. They also eat small algae and marine plants. To catch fish, horned puffins dive to depths of around 30 meters (98 ft), though most hunting takes place at 15 meters (49 ft). They most often hunt in the early morning. They dive head-first into the water, watch for a school of fish while also keeping an eye out for predators, then dive after prey once spotted. Hunting dives usually last between 20 and 30 seconds. Puffins usually swallow several small fish before bringing any remaining prey back to the colony, and do not adjust the position of prey in their beak to avoid losing their catch. Hunting areas are typically located fairly far offshore from the puffins' nesting site. Horned puffins return from hunts carrying several small fish, squid, or crustaceans held in their specialized bills. Chicks have a less varied diet, feeding mainly on sandeel or capelin caught near the coast. Parents deliver these fish to chicks two to six times per day. Unlike many other seabirds that feed their young by regurgitation, horned puffins feed their chicks whole fish directly from the bill. Both parents participate in feeding and rearing the chick.
