Common Loon vs Common Seal

Gavia immer compared with Phoca vitulina

Key Differences

• Common Loon is Not Evaluated while Common Seal is Near Threatened.

Taxonomic Classification

Rank	Common Loon	Common Seal
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Aves (Birds)	Mammalia (Mammals)
Order	Gaviiformes (Gaviiformes)	Pinnipedia (Seals & Sea Lions)
Family	Gaviidae	Phocidae (True Seals)
Genus	Gavia	Phoca (Harbor Seals)
Species	Gavia immer	Phoca vitulina

Evolutionary Relationship

Common Loon and Common Seal share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Common Loon

NE — Not Evaluated

Common Seal

NT — Near Threatened

Population: ~500.0K

Trend: Stable →

Physical Characteristics

Attribute	Common Loon	Common Seal
Diet	—	Carnivore
Average Lifespan	—	30 years
Average Length	—	1.7 m
Average Weight	—	80.0 kg

Habitat & Geographic Range

Common Loon

Habitat

Typically found in various aerial, terrestrial, and aquatic environments.

Range

Distributed across Belgium, Denmark, Norway, Sweden, and United States.

Common Seal

Habitat

Typically found in diverse ecosystems where prey species are available.

Range

Found across Europe (7 countries) and North America (United States). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Common Loon

<em>Gavia immer</em>, the common loon or great northern diver, is a large aquatic bird in the family Gaviidae, known for its haunting, yodeling calls across northern lakes. It is found in Belgium, Denmark, Norway, Sweden, and the United States, breeding on freshwater lakes in boreal and subarctic regions and wintering along marine coastlines. The common loon is adept in aerial, terrestrial, and aquatic environments, though it is most highly specialized for diving, using its strong feet positioned far back on its body to pursue fish underwater. It typically feeds on fish, supplemented by crustaceans and aquatic invertebrates. Its striking summer plumage features a black-and-white checkered back and a deep black head with a characteristic white necklace pattern. The species has not been evaluated for IUCN conservation status. Common loons require clear, fish-rich lakes for successful breeding and are sensitive to water quality degradation and human disturbance at nesting sites. Their distinctive calls are emblematic of wilderness in North America and Scandinavia.

Common Seal

The most widely distributed pinniped, harbor seals inhabit temperate and subarctic coastal waters of both the North Atlantic and North Pacific. Adults reach up to 130 kg and spend roughly equal time at sea hunting fish, squid, and crustaceans and hauling out on beaches or rocks to rest. Their large, expressive eyes are adapted for underwater vision in low light. Harbor seals are a critical food source for orcas, sharks, and polar bears.

Shared Countries

Both species can be found in 5 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇳🇴 Norway 🇸🇪 Sweden 🇺🇸 United States