Rhinoceros Auklet
Rhinoceros Auklet
Cerorhinca monocerata
At a Glance
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.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Auks, Murres, Puffins, Upright-perching Water Birds
IUCN Status
Least Concern
Habitat
Coasts and Shorelines, Open Ocean
Region
Alaska and The North, California, Northwest, Western Canada
Behavior
Direct Flight, Rapid Wingbeats, Swimming
Population
1.500.000
Range & Identification
Migration & Range Maps
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.
Description
14 1/2-15 1/2" (37-39 cm). Yellow bill, two white face stripes (less apparent in winter). Horn on bill is worn only in spring and summer. Winter birds look fairly plain dark gray, known by big-headed look, bill shape and color. Tufted Puffins in winter can be very similar but have thicker bills and larger, rounder heads. Cassin's Auklet is much smaller.
Size
About the size of a Crow
Color
Black, Gray, Orange, White, Yellow
Wing Shape
Narrow, Pointed, Tapered
Tail Shape
Short
Songs and Calls
Low growling notes.
Call Pattern
Flat, Simple
Call Type
Odd
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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Behavior
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.
Feeding Behavior
Forages while swimming underwater. Can remain submerged for up to 2 minutes. May tend to forage closer to shore than puffins.
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.
Conservation
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).
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.