Cormorant And Shag Introduction
The Cormorant & Shag are two species of birds which are frequently confused with each other. Both species are predominantly black and spend a significant proportion of their time resting with their wings outstretched or fishing for their next meal.
Both species also have an almost prehistoric look to their feathers. Just look at the beautiful patterning on this Cormorant. The pattern is reminiscent of the scales on a reptile such as a prehistoric pterodactyl rather than the feathers on a modern-day bird!
Cormorant And Shag Habitat Size Difference
A key physical differentiator between a Cormorant & Shag is the size of the bird. Cormorants are significantly larger than Shags. However, it’s unlikely that you will see them side by side in the field, therefore size sometimes doesn’t help forming a positive ID, especially if the bird you are looking at is in the distance.
Cormorant And Shag Habitat
Habitat can sometimes help. Shags are almost exclusively found in coastal environments, whereas the Cormorant will often visit canals, lochs, and rivers in search of food. Therefore if the bird you are looking at is in-land, it’s highly likely to be a Cormorant.
Let’s look at some of the physical characteristics of each bird starting with the Cormorant.
Cormorant
Family: Phalacrocoracidae
The Cormorant (scientific name Phalacrocorax carbo) has brown-black feathers on its upperparts.
Their underparts are black, but you will sometimes see an emerald sheen to their breast feathers, particularly if seen in good light.
Their eyes are piercing green, and have a ring of bare skin around them; which is an excellent differentiator if you manage to get a closer look at the bird you are trying to identify.
They are heavy-set birds with a wedge-shaped head and heavy-looking bills. Their tails when seen extended out are wedge-shaped.
Cormorants sit very low in the water, and when seen in flight, they look very much like how a pterodactyl is portrayed in flight.
During the breeding season, the Cormorant is easy to identify. They feature a crest on their forehead (as do Shags), but Cormorants exclusively have white feather patches on their chin and thighs.
Juvenile cormorants are brown but tend to be darker brown on their upper parts and lighter brown on their lower parts.
Habitat-wise, Cormorant are often found inland. This habit has developed since the 1950s, and their natural habitat includes coastal environments. Cormorant have a tendency to be solitary animals, but can sometimes be seen in small groups.
Shag
Family: Phalacrocoracidae
The Shag (scientific name Gulosus aristotelis) is around the size of a goose, with a much more slender appearance than a Cormorant.
Their plumage is black with an emerald gloss on their upper and lower parts. The Shag lacks the brown markings seen on the Cormorant’s upper parts. You can sometimes see a purplish tinge to the Shags’ wings.
They have small heads with long slender bills and like the Cormorant, also have green eyes. Unlike the Cormorant, the Shag’s eyes are surrounded by feathers.
The Shag forehead is more peaked than the wedge-shaped head of the Cormorant.
During the breeding season, they develop a tufted crest, but Shags don’t have the same white markings seen on the Cormorant. However, note that Shags do sometimes display a distinctive white throat patch.
Juvenile Shags are brown but their coloring tends to be consistent across both their upper and lower parts.
Habitat-wise, the Shag is a coastal bird and significantly more social than Cormorants. Often seen in large numbers, especially in the breeding season. During this, they congregate at around 10 different breeding sites.
References
Taylor, M. and Dando, J. (2012) RSPB British birdfinder. 1st ed. London, England: Bloomsbury. [Accessed 18/04/2025]
