Rhinoceros Auklet

The Rhinoceros Auklet (Cerorhinca monocerata) is a medium-sized seabird in the auk family and is closely related to puffins. During the breeding season, both males and females can be easily recognized by a distinctive vertical pale yellow “horn” (1 to 3 cm long) at the base of the upper bill, which gives the species its name.
Their backs are gray to brown, with a grayish-brown chest and a buff-white belly. They also have two narrow, cream-colored head plumes—one extending from above the eye and the other from the base of the bill. Their large bill is orange and brown. Leg and foot color can vary from yellow to gray-green, and the eyes are usually yellow-brown.
Rhinoceros Auklets nest in burrows on offshore islands, and are mostly nocturnal at their nesting colonies. During the breeding season, they forage close to shore

Overview

• Species Common Name Rhinoceros Auklet
• Species Scientific Name Cerorhinca monocerata
• State Listing Status Sensitive (pending)

Ecoregions

Nearshore

The Nearshore ecoregion includes a variety of habitats ranging from submerged high-relief rocky reefs to broad expanses of intertidal mudflats in estuaries and hosts a vast array of fish, invertebrates, marine mammals, birds, plants, and micro-organisms. This ecoregion encompasses the area from the outer boundary of Oregon's Territorial Sea to the supra-tidal zone, and up into the estuaries.

Special needs

Rhinoceros Auklets feed primarily on schooling fishes, and at sea are primarily found in continental shelf waters. Deep soils or crevices are required for nests, which are burrows in substrate on offshore islands that lack mammalian predators.

Limiting factors

Rhinoceros Auklets are limited by the availability of marine forage near nesting islands, predation by mammals on nesting islands, and the availability of suitable colony sites. Threats include fisheries bycatch, vulnerability to oil spills, variable marine conditions affecting prey availability, marine development, and plastic pollution.

Data gaps

• Assess population size and demographics. Breeding islands are difficult to access and very few occurrence records exist.
• Assess vulnerability to impacts from climate change
• Assess magnitude of impact and opportunities to reduce mortality from anthropogenic threats including oiling, fishing nets, and collisions
• Assess impacts of offshore wind and determine best practices to reduce or mitigate impacts

Conservation actions

• Develop appropriate survey methodology for populations and habitat.
• Monitor islands for mammalian predator issues.
• Investigate the role of variable prey availability and ocean current changes on survival and recruitment.

Key reference or plan

Pacific Region Seabird Conservation Plan and Survey Protocol. Read here

Oregon Seabird Colony Catalog. Read here