The North American black-and-white sea duck that disappeared around 1875 was the Labrador duck.
The Labrador duck, Camptorhynchus labradorius, was a rare species of the North Atlantic coast. Males had striking black-and-white, eider-like plumage, while females were gray and more subdued. It belonged to a monotypic genus, meaning no other living species shared its genus.
The last preserved specimen was shot on Long Island in 1875, and the last reported sighting was in Elmira, New York, in 1878. That explains why references may give either 1875 or approximately 1878 for its disappearance. The species was already uncommon, and its population declined further between 1850 and 1870.
Scientists have not settled on one cause of extinction. Hunting, egg collection, coastal habitat changes, and the loss of shallow-water mussels and other shellfish have all been proposed. Despite its name, the Labrador duck was not limited to Labrador; it ranged along the North American Atlantic coast.