The semipalmated sandpiper (Calidris pusilla ) gets its common name from the short webs between its toes ("palmated" means webbed) – consequently its feet are half webbed. Its toes are only slightly lobed at their bases, but they do help the bird to walk on mud without sinking. It has black legs and a short, stout, straight dark bill. The body is dark grey-brown on top and white underneath. The head and neck are tinged light grey-brown. The Semipalmated Sandpiper is perhaps the most numerous shorebird in North America, sometimes occurring by the thousands during migration.