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Breeding adult. Photo: Mick Thompson/Flickr (CC-BY-NC-2.0)

Rhinoceros Auklet

Cerorhinca monocerata

A chunky dark seabird, related to the puffins, common at times off the northern Pacific Coast. Often unsuspicious, and boats may approach it rather closely on the water. If pressed, it dives and swims powerfully underwater. Although its takeoff appears clumsy and laborious, it is a fast flier, and may fly long distances to feeding areas daily. The "horn" on the bill, responsible for the bird's name, grows annually in early spring and is shed in late summer.

Conservation status	Not as abundant as some Arctic auks, but still fairly numerous. On Farallon Islands, California, where the species ceased to breed for almost a century, it re-established itself in the 1970s after introduced rabbits were eliminated (rabbits may have competed for burrows).
Family	Auks, Murres, Puffins
Habitat	Ocean, tide-rips; nests in burrows on islands. Often far from land, but may feed close to shore, especially where tidal currents near islands cause upwellings or concentrations of food. In winter flocks may spend night on coastal bays, flying farther out to sea to forage by day. Nests on islands, in burrows in soil under grass, shrubs, trees.

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Feeding Behavior

Forages while swimming underwater. Can remain submerged for up to 2 minutes. May tend to forage closer to shore than puffins.

Eggs

one. White, usually spotted with brown and gray. Incubation is by both sexes, 39-52 days, average 45 days. Young: both parents feed young, carrying fish in bill to nest. Young leaves nest about 7-8 weeks after hatching.

Young

both parents feed young, carrying fish in bill to nest. Young leaves nest about 7-8 weeks after hatching.

Diet

Fish, crustaceans. Food brought to nestlings is mostly small fish, particularly sand lance, herring, and anchovy, also rockfish, smelt, saury, and others. Favors fish that gathers in dense schools. Diet of adults probably similar. Also eats crustaceans.

Nesting

Breeds in colonies, mostly on islands. Generally active around colonies only in evening and at night, although at some colonies the adults visit by day as well. Courtship displays include members of pair nibbling at each other's bills. Advertise ownership of nest site by standing upright, with wings partly opened, pointing bill up and hissing. Nest site is in burrow in ground, typically on slight slope covered with grass, shrubs, trees, sometimes in steep slope or cliff. Burrow up to 20' long, usually 5-10', with one or more side branches. Nest is in chamber in burrow, a shallow cup of moss, twigs.

Illustration © David Allen Sibley.
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Text © Kenn Kaufman, adapted from
Lives of North American Birds

Migration

More strongly migratory than most western auks. Although summer and winter ranges overlap widely, mostly vacates northern part of breeding range in winter, and large numbers move into California waters then.

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Migration

All Seasons - Common
All Seasons - Uncommon
Breeding - Common
Breeding - Uncommon
Winter - Common
Winter - Uncommon
Migration - Common
Migration - Uncommon

Songs and Calls

Low growling notes.

colony sounds

Audio © Lang Elliott, Bob McGuire, Kevin Colver, Martyn Stewart and others.
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How Climate Change Will Reshape the Range of the Rhinoceros Auklet

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect this bird’s range in the future.

Zoom in to see how this species’s current range will shift, expand, and contract under increased global temperatures.

Climate threats facing the Rhinoceros Auklet

Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.