Rhinoceros Auklet vs Least Auklet

In short

The Rhinoceros Auklet is distinguished by its prominent 'horn' on the bill during breeding season, while the Least Auklet is much smaller and lacks this feature. Both species are auks but differ significantly in size and plumage patterns.

Identification tips

• Bill Horn: Look for the Rhinoceros Auklet's horn on the bill during breeding season.
• Size: Note the size difference; Rhinoceros Auklet is larger.
• Plumage: Least Auklet has varied plumage with white facial plumes, unlike the plain Rhinoceros Auklet.
• Behavior: Observe feeding behavior; Rhinoceros Auklet carries fish externally, while Least Auklet dives for zooplankton.

Size

The Rhinoceros Auklet is a medium-sized auk, much larger than the tiny Least Auklet.

Plumage

Rhinoceros Auklet has a plain, dark plumage with a distinctive horn on the bill during breeding. Least Auklet displays more varied plumage, from white to nearly black, with white facial plumes.

Behaviour

Rhinoceros Auklet is mainly nocturnal at colonies, carrying fish externally. Least Auklet is diurnal, diving for zooplankton.

Habitat

Rhinoceros Auklet breeds on islands in the North Pacific, closer to shore. Least Auklet breeds densely at a few sites in the Aleutian and Bering Sea islands.