Common Merganser vs small tortoiseshell

Mergus merganser compared with Aglais urticae

Key Differences

• Common Merganser is Least Concern while small tortoiseshell is Near Threatened.

Taxonomic Classification

Rank	Common Merganser	small tortoiseshell
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Chordata (Chordates)	Arthropoda (Arthropods)
Class	Aves (Birds)	Insecta (Insects)
Order	Anseriformes (Anseriformes)	Lepidoptera (Butterflies & Moths)
Family	Anatidae	Nymphalidae (Brush-footed Butterflies)
Genus	Mergus	Aglais
Species	Mergus merganser	Aglais urticae

Evolutionary Relationship

Common Merganser and small tortoiseshell share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Common Merganser

LC — Least Concern

small tortoiseshell

NT — Near Threatened

Physical Characteristics

Attribute	Common Merganser	small tortoiseshell
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Merganser

Habitat

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

Range

Found across Europe (5 countries) and North America (United States).

small tortoiseshell

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Found across Europe (41 countries). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Common Merganser

<em>Mergus merganser</em>, the common merganser or goosander, is a large diving duck in the family Anatidae, broadly distributed across Europe and North America. It is classified as Least Concern on the IUCN Red List. This species is capable of aerial, terrestrial, and aquatic locomotion, but is most specialized for underwater pursuit of prey. The common merganser is typically piscivorous, diving in clear, fast-flowing rivers and lakes to catch fish using its serrated bill, which provides a firm grip on slippery prey. Males display striking breeding plumage with a dark green head, white body, and red bill, while females are grey with a rusty-brown head and crested nape. The species nests in tree cavities, cliff ledges, and artificial nest boxes near freshwater habitats. It requires clean, well-oxygenated rivers and lakes for foraging, making it sensitive to water quality degradation and overfishing of prey species. Common mergansers are migratory in northern parts of their range, moving to coastal and ice-free inland waters during winter months.

small tortoiseshell

small tortoiseshell (Aglais urticae) 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.

Shared Countries

Both species can be found in 5 countries:

🇧🇪 Belgium 🇩🇰 Denmark 🇱🇺 Luxembourg 🇳🇴 Norway 🇸🇪 Sweden