Guillemot vs Razorbill for Kids
Common guillemots and razorbills can stand side by side in a North Atlantic seabird city. This comparison uses the common guillemot, Uria aalge, called the common murre in North America, and the razorbill, Alca torda. Both are flying auks that dive with their wings and raise one chick on rocky coasts. The common guillemot is heavier, dark chocolate-brown at close range, and has a long thin pointed bill. It packs onto exposed ledges and usually lays one colourful pointed egg without a nest. The razorbill looks blacker and has a deep blunt bill crossed by a white band, usually nesting in a crack, crevice, or boulder shelter.
Common Guillemot
- Type: Deep-Diving Crowded-Ledge Auk
- Group: Living species Uria aalge in auk family Alcidae and shorebird order Charadriiformes, called common guillemot in Britain and common murre in North America
- Known for: Heavy body, long thin pointed bill, dark chocolate-brown to blackish head and back, white belly, optional white bridled eye marking in some Atlantic birds, enormous packed cliff colonies, no built nest, one variable pointed egg, deep dives, and an early chick journey to sea
- Diet: Marine carnivore and piscivore eating mostly small fish such as capelin, sandlance, cod, pollock, herring, rockfish, smelt, and anchovy, plus squid, octopus, krill, amphipods, and other crustaceans
- Special skill: Combining rapid air flight with dives recorded to about 180 metres, then laying one highly variable pointed egg directly on a packed bare ledge without building a nest
Razorbill
- Type: Deep-Billed Crevice-Nesting North Atlantic Auk
- Group: Living species Alca torda, the only surviving member of genus Alca, in auk family Alcidae and shorebird order Charadriiformes
- Known for: Deep blunt black bill flattened side to side, white vertical bill band, fine white line toward the eye, yellow mouth, jet-black breeding upperparts, white belly, rocky crevice nest, wing-propelled diving, schooling-fish diet, and a chick escorted to sea by its father
- Diet: Marine carnivore and piscivore eating mainly small schooling fish such as sandlance, capelin, herring, sprat, and young cod, plus smaller amounts of krill, other crustaceans, marine worms, and molluscs
- Special skill: Using a deep serrated bill and compact wings to herd and grip schooling fish during dives recorded to about 100 metres, then guiding a flightless chick from cliff to open sea
Quick Answer
Quick answer: Look first at the bill and nesting position. A common guillemot has a long slim pointed bill, brown-black head and back, very short tail, and often stands tightly packed on an open ledge around one exposed egg. A razorbill has a much deeper blunt black bill with a white band, a fine white line toward the eye, a longer visible tail, and usually uses a protected crack or boulder crevice. Guillemots are also heavier and have the deeper documented maximum dive. Both are auks, not penguins.
Common Guillemot vs Razorbill: Quick Comparison
| Feature | Common Guillemot | Razorbill |
|---|---|---|
| Scientific identity | Uria aalge; common murre in North America | Alca torda |
| Adult size | About 38-43 cm and 800-1,125 g | About 43 cm and 505-890 g |
| Bill | Long, slim, straight, and pointed | Deep, blunt, laterally flattened, grooved, and white-banded |
| Breeding upperparts | Blackish to rich dark chocolate-brown at close range | Usually glossy jet black |
| Face detail | Some Atlantic birds have a white eye ring and rear stripe called a bridle | Thin white line runs from bill toward eye |
| Typical nest site | Open crowded cliff ledge, with no built nest | Protected crack, crevice, boulder shelter, or narrow ledge |
| Egg | One highly variable pointed egg laid directly on rock | One whitish blotched egg in a scrape or sheltered site |
| Colony spacing | Extremely dense, often shoulder-to-shoulder | Colonial but usually more separated by crevice sites |
| Documented dive | Recorded to 591 ft or about 180 m | Recorded to 330 ft or about 100 m |
| Standout clue | Thin pointed bill and packed brown-black ledge birds | Thick white-banded bill, blacker head, and longer tail |
How Are Common Guillemot and Razorbill Alike?
- Both are living auks in family Alcidae with black-and-white countershading, webbed feet, compact bodies, and short wings used in air and underwater.
- Both spend most of the year on northern oceans, come ashore mainly to breed, and gather in large mixed seabird colonies on rocky cliffs.
- Both eat mainly schooling fish, catch prey during wing-propelled dives, and can swallow smaller catches underwater.
- Both form long-lasting pairs, lay one egg, share incubation and chick feeding, and often return to the same precise breeding area.
- Both send a partly grown chick to sea before it can fly properly, with the male parent guiding and feeding it after departure.
How Are Common Guillemot and Razorbill Different?
- The common guillemot is much heavier on average, while the razorbill is lighter even though their body lengths overlap.
- The guillemot has a narrow pointed bill, while the razorbill has a deep blunt black bill with a white vertical band.
- The guillemot looks dark brown at close range, while the breeding razorbill usually looks glossier black above.
- The guillemot normally lays directly on an exposed packed ledge without a nest, while the razorbill more often uses a protected crevice or scrape.
- The common guillemot has been recorded diving substantially deeper, while the razorbill’s documented maximum is about 100 metres.
Common Guillemot vs Razorbill Showdown
Adaptation showdown: Common Guillemot wins size because its 800-1,125-gram measurement range is heavier than the Razorbill’s 505-890 grams, although their lengths overlap. Speed is a Tie because no fair matched air or water race supports a winner. Strength is a Tie because both have powerful flight muscles and fish-gripping bills without matched force tests. Stealth is a Tie because both share black-and-white countershading. Common Guillemot wins social behaviour for nesting in exceptionally dense shoulder-to-shoulder ledge groups with close neighbour interactions. Common Guillemot wins swimming because its recorded 591-foot maximum dive exceeds the Razorbill’s 330-foot record, although most dives by both are shallower. Common Guillemot wins weirdest for laying one dramatically pointed, individually patterned egg directly on bare rock inside a crowded colony without building a nest; the old claim that shape alone stops cliff falls is not settled science.
Fun Common Guillemot vs Razorbill Facts
Guillemot and Common Murre Mean the Same Species
British and European English usually call Uria aalge the common guillemot, while North American guides call it the common murre. The names change across the Atlantic, but the scientific species does not.
The Bill Solves the Lookalike Puzzle
A common guillemot’s bill is long, slim, and pointed. A razorbill’s bill is much deeper and flatter from side to side, with grooves and a white band. At close range, the guillemot also looks chocolate-brown rather than glossy black.
Guillemots Build No Real Nest
A pair returns to a tiny patch on a busy ledge and places its single egg directly on rock, though small pebbles may gather around it. Neighbours can stand almost shoulder-to-shoulder, making voice, site, and egg recognition important.
The Famous Pointed Egg Has a Complicated Story
Guillemot eggs vary from pale to turquoise and carry distinctive spots and scrawls. Their pointed form has often been said to stop them rolling off cliffs, but experiments show the explanation is not that simple; shape may also help strength and cleanliness in crowded conditions.
Both Chicks Leave Before Proper Flight
A partly grown guillemot or razorbill chick departs the cliff before its flight feathers are complete. The male follows it to sea, provides food, and helps it continue developing away from the crowded breeding ledge.
Common Guillemot vs Razorbill Quiz
- What is a common guillemot called in North America? Answer: A common murre.
- Which bird has the thinner pointed bill? Answer: The common guillemot.
- Which bird has a white band across its deep black bill? Answer: The razorbill.
- Which bird usually lays directly on a crowded bare ledge? Answer: The common guillemot.
- Which bird has the deeper documented maximum dive? Answer: The common guillemot.
Common Guillemot vs Razorbill FAQ
Are guillemots and razorbills the same bird?
No. They are separate auk species with different bill shapes, average body mass, nesting positions, and dive records.
Is a common guillemot also a common murre?
Yes. Common guillemot is the usual British name and common murre the usual North American name for Uria aalge.
How can I tell them apart on a cliff?
Look for the guillemot’s thin pointed bill and brown-black packed body versus the razorbill’s deep white-banded bill, blacker head, and more sheltered position.
Does a pointed guillemot egg always roll in a safe circle?
No. It may arc when moved, but experiments show shape alone does not guarantee that it will remain on a ledge.
Can both birds fly and swim?
Yes. Both fly rapidly through air and flap their wings underwater to pursue fish.
Animal Words to Know
- Guillemot: The British common name for several auk species; here it means Uria aalge, the common murre.
- Murre: The North American name for guillemots in genus Uria.
- Bridled form: A common guillemot colour form with a white eye ring and white line extending behind the eye.
- Pyriform: Pear-shaped or strongly pointed at one end, as in a common guillemot egg.
- Ledge: A narrow shelf of rock on a cliff where seabirds may breed.
Design a Crowded Auk Cliff Guide
Design a Crowded Auk Cliff Guide
Draw a North Atlantic seabird-cliff identification scene with both adult auks at honest shared scale. Make the common guillemot heavier-bodied and chocolate-brown-black with a long thin pointed bill, very short tail, dense shoulder-to-shoulder ledge group, and one highly variable pointed egg laid directly on rock; include a small bridled-face inset. Make the razorbill slightly longer-looking but lighter, jet black above, with a deep blunt laterally flattened bill, white bill band, white line toward the eye, longer visible tail, and a protected crevice. Add underwater dive silhouettes and chick-with-father scenes. Label common guillemot, common murre, thin bill, thick bill, brown-black, jet black, bare ledge, crevice, pointed egg, 180 m record, and 100 m record.
Meet Each Animal
Want the full fact file? Here are quick highlights from each animal’s own facts page.
Common Guillemot Fact Highlight
From the full animal facts pageRazorbill Fact Highlight
From the full animal facts pageMore Animal Comparisons
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