The rhinoceros auklet (Cerorhinca monocerata) is a small seabird and a member of the auk family. It is found along the Pacific coast of North America from Alaska to Baja California. The rhinoceros auklet gets its name from the horn-like projection on its bill. This distinctive bill has given rise to the common name “horn-billed puffin” as well. However, while the rhinoceros auklet resembles puffins in some ways, it is not actually classified as a true puffin.
What are puffins?
Puffins are a group of seabirds in the genus Fratercula. There are three main species of puffin:
- Atlantic puffin (Fratercula arctica)
- Horned puffin (Fratercula corniculata)
- Tufted puffin (Fratercula cirrhata)
All puffin species have brightly colored bills, predominantly black and white plumage, and nest in colonies on cliffs and offshore islands. They are excellent swimmers and divers, using their wings to “fly” underwater in search of small fish and marine invertebrates.
Comparison of rhinoceros auklets and puffins
While the rhinoceros auklet shares some similarities with puffins, there are some key differences:
| Feature | Rhinoceros auklet | Puffins |
|---|---|---|
| Taxonomy | Order: Charadriiformes Family: Alcidae |
Order: Charadriiformes Family: Alcidae Genus: Fratercula |
| Bill shape | Long, thin, horn-like projection | Short, thick, and colorful |
| Plumage | Grey and white | Black and white |
| Nesting habits | Burrows in soil | Rocky crevices and cliffs |
As the table shows, while puffins and rhinoceros auklets are both alcids, the rhinoceros auklet is not classified within the puffin genus Fratercula. The rhinoceros auklet has a distinctive bill shape, plumage pattern, and nesting behavior compared to true puffins. Based on these differences, rhinoceros auklets are considered a separate type of auk, not a true puffin.
Detailed Comparison
Taxonomy
Taxonomically, puffins and rhinoceros auklets are both part of the family Alcidae, which includes the auks. However, puffins belong to the genus Fratercula, whereas the rhinoceros auklet is placed in the genus Cerorhinca. So while they are closely related as auks, rhinoceros auklets are not classified within the puffin genus.
Appearance
In terms of appearance, puffins have short, triangular bills that are brightly colored with red, yellow, blue, and orange during the breeding season. Their plumage is also very distinctive – predominantly black and white.
In contrast, the rhinoceros auklet has an all grey and white plumage. Its most unique feature is its long, slender bill that has a horn-like projection. This gives it a very different look from puffins.
Behavior
Puffins and rhinoceros auklets exhibit some different behaviors as well:
- Puffins nest in colonies on rocky cliffs and islands, whereas the rhinoceros auklet nests solitarily in self-dug burrows in the soil.
- Puffins can flap their wings up to 400 beats per minute to “fly” underwater, while the rhinoceros auklet flaps its wings much more slowly at only 60 beats per minute.
- Puffins form long-term pair bonds, while rhinoceros auklet pairs only remain together for a single breeding season.
These differences in nesting, diving, and bonding behaviors further set puffins and rhinoceros auklets apart.
Rhinoceros Auklet Description
To understand why the rhinoceros auklet is not a puffin, let’s look at its physical characteristics and behavior in more detail:
Physical characteristics
- Length: 25-28 cm
- Wingspan: 45-50 cm
- Weight: 260-345 g
- Plumage: Grey and white overall. White underparts, grey back and wings. White “eyebrows.”
- Bill: Long, thin, pale grey. Orange or reddish tip. Distinctive horn-like projection.
- Eyes: Dark brown
- Legs and feet: Pink
The rhinoceros auklet lacks the bold black and white plumage of puffins. Its most distinctive feature is the horned projection on its bill.
Behavior
- Feeding: Dives from surface to catch small fish, squid, and crustaceans. Swims underwater using wings for propulsion.
- Breeding: Solitary nester. Excavates burrows or uses rock crevices. Single egg clutch.
- Social: Colonies gather at sea and on shore. Monogamous pairs only remain together for one breeding season.
- Vocalizations: Growling and trumpeting noises, especially at breeding colonies.
The rhinoceros auklet does not nest colonially on cliffs like puffins. Its vocalizations and social behavior also differ from puffins.
Puffin Description
For comparison, here are some key facts about puffins:
Physical characteristics
- Length: 25-30 cm
- Wingspan: 50-60 cm
- Weight: 400-550 g
- Plumage: Black and white. Black crown, back, and wings. White underparts and face.
- Bill: Short, broad, and brightly colored
- Eyes: Red, orange, yellow, or blue
- Legs and feet: Orange
The bold black and white plumage and short colorful bill are distinguishing features of puffins.
Behavior
- Feeding: Dives from air or surface. Flaps wings rapidly underwater. Catches fish, crustaceans, and marine invertebrates.
- Breeding: Colonial nester on cliffs and rocky islands. Grass-lined burrows or rock crevices. Single egg clutch.
- Social: Colonies can number in the thousands. Long-term pair bonds.
- Vocalizations: Growling, trumpeting, and billing noises at colonies.
Puffins exhibit more colonial nesting habits than rhinoceros auklets. They also form long-term pair bonds.
Conclusion
In summary, while the rhinoceros auklet is closely related to puffins, it is considered a distinct species, not a true puffin. The key differences include:
- Taxonomy – puffins are in the genus Fratercula, rhinoceros auklets are Cerorhinca
- Bill shape – puffins have short colorful bills, the rhinoceros auklet bill has a horn-like projection
- Plumage – puffins are black and white, rhinoceros auklets are grey and white
- Nesting – puffins nest colonially on cliffs, rhinoceros auklets nest solitarily in burrows
Based on these physical and behavioral differences, rhinoceros auklets are not classified within the puffin group. So while the common name “horn-billed puffin” is sometimes used, the rhinoceros auklet is a distinct type of auk, not a true puffin species. Understanding the taxonomy and characteristics of these seabirds shows why the rhinoceros auklet is not considered a puffin despite some similarities.
