Cormorant Vs Shag: Key Differences Explained

The coastal waters and inland waterways of the United Kingdom are home to two remarkable aquatic birds: the Cormorant (Phalacrocorax carbo) and the Shag (Gulosus aristotelis). While these birds may appear similar at first glance, they each possess unique characteristics that set them apart.

Did you know that both species can dive to impressive depths of up to 45 metres to catch their prey? Or that despite their aquatic prowess, neither bird has completely waterproof feathers, leading to their iconic wing-spreading behaviour to dry off?

Whether you’re a seasoned birdwatcher or a curious nature lover, understanding the key differences between these birds can enhance your appreciation of UK wildlife.

Table of Contents

Key Takeaways

Shags are generally smaller and slimmer than Cormorants
Cormorants are more adaptable, found both inland and coastal, while Shags stick primarily to rocky coasts
Shags have a steeper forehead profile and a distinctive green sheen during breeding season
Cormorants weigh 2.1-2.5 kg, while Shags are lighter at 1.75-2.25 kg
Cormorants have a larger wingspan (130-160 cm) compared to Shags (90-105cm)
Shags are of higher conservation concern, being on the UK Amber List
Both species are expert divers and fishers, capable of reaching depths of 45 metres

What Is The Difference Between A Cormorant And A Shag?

While Cormorants and Shags belong to the same family and share many characteristics, they differ in size, habitat preferences, and appearance. Let’s explore these differences in detail.

Visual Differences

The most noticeable visual distinction between these birds is their size and build.

Cormorants are larger and more robust, with a thick neck and relatively flat forehead. They have a distinctive black plumage that can appear slightly bronzed in sunlight.

Shags, in contrast, are more slender with a distinctive steep forehead and smaller head in proportion to their body. During the breeding season, they display a beautiful dark, glossy green sheen and sport a recurved crest on their head, making them particularly striking.

Young birds also differ in appearance. Juvenile Cormorants are brown with a white belly, while young Shags are dark in colour and gradually lighten as they age.

Differences In Habitat

Habitat preferences provide one of the clearest distinctions between these species. Cormorants are highly adaptable birds, found in diverse environments including urban areas, marine zones, and inland waterways. They’re equally at home on coastal cliffs or inland reservoirs.

Shags, however, are more specialised in their habitat choice. They are primarily coastal birds, with a strong preference for rocky shores and cliffs. Unlike Cormorants, Shags rarely venture far inland and are typically found within 100-200 km of their breeding sites.

Nests & Eggs

Both Cormorants and Shags nest in colonies, but their nesting habits differ slightly.

Cormorants build their nests on cliffs, rocky outcrops, and sometimes in trees near water. These nests are made of twigs, seaweed, and grass. They lay 3 to 4 pale blue-green eggs that gradually become stained over time.

Shags also prefer coastal cliffs and rocky areas for nesting, but their nests are typically smaller and less elaborate than those of Cormorants. Shags lay 2 to 3 eggs that are white with a rough texture.

Both species exhibit strong parental care, with both parents involved in incubation and feeding duties.

Bird Calls

Both Cormorants and Shags are relatively quiet birds, especially outside of the breeding season. However, they do make distinctive sounds during breeding. Cormorants produce deep, guttural croaks and grunts, particularly around their nests.

Shags also produce guttural, rasping calls during the breeding season, but these are typically higher-pitched than Cormorants’. Their calls include various grunts and growls, often heard near their coastal nests.

Size & Weight

When it comes to size, Cormorants are notably larger than Shags. Cormorants measure between 80 to 100 cm in length, with a weight range of 2.1 to 2.5 kg, making them one of the heavier seabirds found around UK shores. Their wingspan, which reaches up to 160 cm, also sets them apart from the smaller Shag.

Shags, in comparison, are more compact, measuring 65 to 80 cm in length and weighing between 1.75 to 2.25 kg. Their wingspan is also smaller, at 90 to 105 cm. This difference in size is one of the most obvious ways to distinguish the two species when observed side by side.

Frequently Asked Questions

What is the main difference between a Cormorant and a Shag?

The main difference between a Cormorant and a Shag is their size and habitat preferences. Cormorants are larger and more commonly found in both coastal and inland waters, whereas Shags are smaller and tend to stay near rocky coastal areas.

Can Cormorants and Shags be found in the same area?

Yes, Cormorants and Shags can be found in the same coastal areas, but Cormorants are more likely to venture inland to lakes and rivers, while Shags prefer to stay near the sea, particularly around rocky cliffs and shorelines.

How can you tell a Shag from a Cormorant?

You can tell a Shag from a Cormorant by their size, plumage, and crest. Shags are smaller, have a glossy green sheen in breeding plumage, and sport a distinctive tufted crest, especially during the breeding season. Cormorants are larger, darker, and lack this crest.

Do Cormorants and Shags have the same diet?

Both Cormorants and Shags primarily eat fish, but Shags also include crustaceans and molluscs in their diet. Both birds are proficient divers, using their long necks and hook-tipped bills to catch prey underwater.