Waterbird prints

Duck prints in the snow

These tracks were made by ducks.

Like other birds, ducks have three toes pointing forward but their tracks may also show signs of the webbing in between the toes. This webbing is useful when the ducks are swimming, as it provides a bigger surface area for better propulsion through the water. Gulls and other water birds also have webbed prints.

Coots

Coot print in the snow
A coot print in the snow

Although coots are waterbirds their feet don't have the webbing, so their prints look much more similar to other birds, but you can see that their toes are wider to help them swim. 

A print left in the snow by a moorhen
A print left in the snow by a moorhen

Moorhens are waterbirds whose prints look very much like wildfowl prints, you can't see any webbing between their toes.