Rhinoceros Auklet (Cerorhinca monocerata)

Rhinoceros Auklet

[order] CHARADRIIFORMES | [family] Alcidae | [latin] Cerorhinca monocerata | [UK] Rhinoceros Auklet | [FR] Macareux rhinoceros | [DE] Nashornalk | [ES] Alca Unicornea | [NL] Neushoornalk


Genus Species subspecies Breeding Range Breeding Range 2 Non Breeding Range
Fratercula monocerata
Cerorhinca monocerata EU, NA n Pacific coasts n PO

Physical charateristics

A dark stubby seabird. Breeding plumage (acquired in late winter): White”mustaches,” narrow white plume behind eye, short erect horn at base of yellowish bill. Non-breeding:
Note the size and uniform dark color. The white plumes are shorter, the horn absent. Immature is similar, with smaller, darker bill.

Listen to the sound of Rhinoceros Auklet

[audio:http://www.aviflevoland.nl/sounddb/R/Rhinoceros Auklet.mp3]

Copyright remark: Most sounds derived from xeno-canto

wingspan min.: 52 cm wingspan max.: 60 cm
size min.: 36 cm size max.: 40 cm
incubation min.: 43 days incubation max.: 47 days
fledging min.: 48 days fledging max.: 53 days
broods: 1   eggs min.: 1  
      eggs max.: 1  


Eurasia, North America : North Pacific coasts


Ocean, rip currents; 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.


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. Courtshi
p 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 and twigs.
Eggs: 1. 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 habits

Fish, crustaceans. Food brought to nestlings is mostly small fish, particularly sand lance, herring, and anchovy, also rockfish, smelt, saury, and others. Diet of adults probably similar. Also eats crustaceans.
Behavior: Forages by diving and swimming underwater, propelled by wings, using feet for steering. Can remain submerged for up to 2 minutes.


This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Rhinoceros Auklet status Least Concern


North Pacific (both sides). 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.

Distribution map

Rhinoceros Auklet distribution range map

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