The Buff-breasted Sandpiper is a medium-sized shorebird that breeds sporadically along arctic coasts from central Alaska to Devon Island, Canada. It winters in South America on the pampas of Argentina, Uruguay, and Paraguay, where individuals frequent heavily grazed grasslands and grasslands adjacent to wetlands. Northward migration of this species proceeds through central South America, across the Gulf of Mexico, and through the central United States and Canada before the birds reach the arctic coast. Southward migration follows a similar route, but over a much broader front.
Buff-breasted Sandpipers are unique among North American shorebirds in having a lek mating system. Males defend relatively small territories that provide no resources for females and are simply display sites to which females can be attracted. Females select a mate and then leave to nest and raise their chicks elsewhere.
Once abundant, this species decreased substantially in numbers owing to commercial hunting in the late 1800s and to loss of habitat along its migratory route in the central United States and its wintering grounds in South America. The extreme tameness of the Buff-breasted Sandpiper and its tendency to return to a wounded flock member made these birds especially vulnerable to hunting. Recent surveys on the migration corridor suggest this species may still be declining, although more study is needed to accurately determine the size of its population.