The Sandwich tern is a large bird with a long and evenly pointed beak. In summer, the top half is light grey, the lower half is white, and the wings have a wide white rear edge. The outer 4–5 primary feathers darken over the summer, forming a greyish-black wedge on the wing tip. The legs and beak are black, the beak tip is yellow. In winter, the forehead and crown are white with only a narrow dark ‘face mask’ remaining.
The common shelduck is a goose-like duck of medium size with a long neck and distinctive plumage. The body is stout, the beak is strong and has a noticeable forehead hump, the legs are quite long. The plumage has extensive white areas, the head is dark green, the beak is red and there is a wide rust-brown stripe across the breast. The shoulder and flight feathers, the tip of the tail and the stripe down the middle of the belly are black. The legs of an adult bird are dull pink, whereas those of a juvenile bird are greyish. The male bird’s beak is bright red with a massive red knob, but the female bird’s beak is often duller red with a little beak knob.
In contrast to the common redshank, which has a more slender build, longer legs and a longer, finer beak with a very small downward bend at the tip, the base of the beak is only red on the lower part of the beak. A white eyebrow is clearly visible in winter and juvenile plumage. The white stripe continues at the preen gland area as a narrow white ‘crack’. The male bird is completely black in summer, only the top part is slightly dotted and the legs are also black. The female bird has a lot more white dots on the belly and sides. In winter, both adult birds are light grey on the top side and pure white on the underside, the front of the neck and ‘face’ are dirty white. The juvenile bird’s underside is uniformly streaked, and the edges of the large coverts and tertials are finely streaked. The legs are red.
Similar to the green sandpiper but lighter brown in appearance, with larger spots on the top side, longer legs, a narrow-striped tail and sparse stripes on the chest and sides. A pale brow stripe extends behind the eye and the legs are yellowish-green. In flight, the wings’ pale undersides are visible and the toes extend entirely past the tip of the tail. In the summer, the top part of the adult bird is irregularly marked with little white and cream spots, whereas in the winter, the plumage is greyer and more uniform.