The Knot is a medium sized wader. These were right by the side of the road on the causeway, so you couldn't fail to see them on the way to the Castle. There were a good number (100+) there but they may have been part of a larger flock - they tend to be in very large flocks on estuaries and rocky shores. These are in winter plumage, which is very grey, with distinctive greenish legs. They appear to be quite a warm shade of grey here, as the sun was very low (mid December). They are winter visitors, but you can occasionally see them in the summer, when they are much more recognisable with a bright coppery-orange front and underside - then they are known as Red Knots.