South Dakota
Birds and Birding
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Rhinoceros Auklet

Cerorhinca monocerata

Length: 15 inches Wingspan: 22 inches Seasonality: Non-resident in South Dakota
ID Keys: Dark gray upperparts, lighter gray underparts.  In breeding, orange bill with fleshy protuberance, and 2 white plumage stripes

Rhinoceros Auklet - Cerorhinca monocerataThe Rhinoceros Auklet is a large seabird, closely related to puffins.  They are named for the fleshy protuberance that grows on their upper mandible each spring before the breeding season.  The 'horn' is lost each fall, only to regrow the following spring.  Outside of the breeding season, they are sometimes confused with the Tufted Puffin, but the bill of a Rhinoceros Auklet is much less massive than a puffin's bill at all seasons.  Populations on some former breeding colonies crashed after the accidental introduction of rodents.  Active efforts to remove all rats and rabbits from some islands have led to successful recolonization of former nesting colonies.

Habitat: During the summer breeding season, found on islands with suitable soil for digging nesting burrows.  At other seasons, tends to forage out at sea where upwelling currents concentrate fish and other prey, but moves closer to shore to overnight in and around protected coastal waters.

Diet: Feeds on fish and crustaceans such as shrimp and amphipods..

Behavior: Feeds by diving and swimming underwater.

Nesting: The nest of a Rhinoceros Auklet is a burrow, built in grassy areas with scattered rocks or trees.  The burrow may be up to 20 feet long, ending in a nesting chamber with a nest built of mosses, seaweed and twigs.  The female lays one egg per season.  Both the parents help to incubate the egg, and both parents help feed the young upon hatching.

Song: On breeding colonies, low moaning calls and shorter barking calls are heard.  Outside of the breeding season, they are mostly silent.

Migration: While some auks in the north Pacific are relatively permanent residents, the Rhinoceros Auk is strongly migratory.  Most birds leave the northern part of their range in the fall and move southward along the Pacific Coast. 

Similar Species: Generally unmistakable if seen well, but possibly confused with Tufted Puffin and Horned Puffin species in non-breeding plumage.

Conservation Status: Populations are undoubtedly lower now than prior to colonization of North America, and there are indications that populations have continued to decline in recent decades. However, they are still widespread and relatively common in many areas. The IUCN lists the Rhinoceros Auklet as a species of "Least Concern".

Further Information: 1) Alaska SeaLife Center - Rhinoceros Auklet

2) BirdWeb.org - Rhinoceros Auklet

3) Alaska Seabird Information Series - Rhinoceros Auklet

Photo Information: Photo taken in June 2008 - Alaska SeaLife Center in Seward, Alaska - Terry Sohl

 

Click below for a higher-resolution map
Rhinoceros Auklet - Range Map
South Dakota Status: Non-resident in South Dakota