Telling the difference

One of the questions I get asked the most is:

“How do you tell the difference between a cormorant and a shag?”

Now, assuming they want a serious answer and not a punchline, there are several things we can look for. Here is a picture of a cormorant and a shag standing next to each other:

There are immediately some obvious differences.

  • Cormorants are much bigger than shags.
  • Cormorants have a heavier, thicker beak.
  • Shags have far less yellow and white skin where the beak meets the face.
  • There is a different in colouration when the feathers catch the sun. Shags tend to look green, while cormorants look blue. (Funnily enough the welsh for shag is fulfran werdd which translates literally as “Green Cormorant”)
  • In this picture, the shags have crests which makes them very easy to identify. Unfortunately, these are only present during the breeding season and not present at all on younger birds.

This is a picture of a young shag:

This was taken at around the same time as the image above. As you can see no crest and no green colouring. There are still some things that we can use to distinguish this from a cormorant:

Where the beak meets the head, there is less yellow skin than would be found on a cormorant.

The shape of the head is also different, as can be seen in this photo, the front of the head slopes steeply, while the back of the head slopes gently as can be seen in this picture of a cormorant colony.


Now this is all very well when you see a bird standing on a rock, giving you a clear view but what do you do when the bird is on the water, usually at the bottom of a cliff?

Handily there is an easy way you watch the birds dive. Cormorants will slip smoothly under the water while shags will kick their legs into the air as they dive.

So in summary the easiest things to look for when trying to tell the difference are:

  • The shape of the head and beak
  • The amount of yellow skin on the face
  • The diving action

Hope this helps!


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