Common Eider vs Great Blue/Cocoi Heron

Somateria mollissima compared with Ardea herodias

Key Differences

• Common Eider is Near Threatened while Great Blue/Cocoi Heron is Least Concern.

Taxonomic Classification

Rank	Common Eider	Great Blue/Cocoi Heron
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class same	Aves (Birds)	Aves (Birds)
Order	Anseriformes (Anseriformes)	Pelecaniformes (Pelecaniformes)
Family	Anatidae	Ardeidae
Genus	Somateria	Ardea
Species	Somateria mollissima	Ardea herodias

Evolutionary Relationship

Common Eider and Great Blue/Cocoi Heron share a common ancestor at the Class level: Aves. (Birds)

Conservation Status

Common Eider

NT — Near Threatened

Great Blue/Cocoi Heron

LC — Least Concern

Physical Characteristics

Attribute	Common Eider	Great Blue/Cocoi Heron
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Eider

Habitat

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

Range

Found across Europe (5 countries) and North America (United States). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Great Blue/Cocoi Heron

Habitat

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

Range

Widely distributed across Europe (5 countries), North America (United States), and South America (Colombia, Ecuador, Venezuela).

Common Eider

Common Eider (Somateria mollissima) is classified as Near Threatened (NT) on the IUCN Red List. Close to qualifying as threatened, with populations that may become vulnerable without conservation action.

Great Blue/Cocoi Heron

Great Blue/Cocoi Heron (Ardea herodias) is classified as Least Concern (LC) on the IUCN Red List. Widespread and abundant across its range, with stable populations and no immediate conservation concerns.

Shared Countries

Both species can be found in 3 countries:

🇧🇪 Belgium 🇳🇴 Norway 🇺🇸 United States