Small, grayish-brown sandpiper. Typically shows relatively short, blunt-tipped bill, but this varies across the breeding range: western populations are shortest-billed, eastern populations are longest, and females have longer bills than males! Also note blackish legs, although they can appear dull gray or greenish. In breeding plumage, fairly pale grayish brown, sometimes with brighter rusty cap and cheek. Nonbreeding is plain gray above and white below. Juveniles have attractive scaly pattern on upperparts, and variable coloration: usually grayish with some buffy areas, occasionally brighter rufous. Most similar to Western and Least Sandpipers. Western averages slightly larger and longer-billed, with brighter rufous on breeding adults and juveniles; nonbreeding birds paler but extremely similar to Semipalmated. Least Sandpiper is darker and browner. Breeds on high Arctic tundra. Migrates to South America for the winter; very rarely lingers in the U.S. past November, unlike Western Sandpiper. Usually found in flocks, sometimes in very large numbers. Prefers open mudflats, but also found in marshes and beaches.