For centuries, humans across the globe have used down feathers for insulation. Russian documents from the 1600s list "bird down" among the goods sold to Dutch merchants, and communities in northern Norway began protecting the nests of eider ducks as early as 1890. Eiders are still "farmed" by people in Iceland, Scandinavia and Siberia. The birds are provided with nest sites and protected from predators, and down is collected intermittently during the nesting season without harming the nests or female ducks. The first collection is made roughly halfway through the incubation period, when some of high quality down is removed per nest. When the eggs have hatched and the young have left the area, the remaining down and breast feathers are gathered, typically resulting in another of lower quality feathers per nest. In general, 50–60 nests will produce about one kilogram (2.2 pounds) of down feathers. This means that only a few thousand pounds of eider down is collected from wild nests each year. Approximately 70% of that harvest is from Iceland.