The Alaska breeding population of the Steller's Eider (Polysticta stelleri) occurs as two subpopulations, one on the Arctic coastal plain of northern Alaska, primarily near Barrow, and the other on the Yukon–Kuskokwim Delta of western Alaska. In 1997, the Alaska breeding population was listed under the Endangered Species Act as threatened because the nesting range and population were thought to have decreased substantially. The historical (pre-1970) and recent (1970–present) breeding distribution and abundance of Steller's Eiders, however, are not well known.