The Merganser is a fish eating diving duck, normally found on the coast. These were seen near the shore on the eastern side of the castle. The male and female are quite different. The females which are grey, with a red-brown head. The male is grey and brown with a deep green head. They both have spiky hair, red bills and red legs and feet, so are quite distinctive. Their bills have serrated edges like teeth, which is why these and similar birds are known as sawbills.

