's
Lady with an Ermine, 1489–1490 Several mustelids, including the mink, the
sable (a type of marten), and the
stoat (ermine), possess
furs that are considered beautiful and valuable, so have been hunted since prehistoric times. From the early Middle Ages, the
trade in furs was of great economic importance for northern and eastern European nations with large native populations of fur-bearing mustelids, and was a major economic impetus behind Russian expansion into
Siberia and French and English expansion in North America. In recent centuries
fur farming, notably of mink, has also become widespread and provides the majority of the fur brought to market. One species, the
sea mink (
Neogale macrodon) of New England and Canada, was driven to
extinction by fur trappers. Its appearance and habits are almost unknown today because no complete specimens can be found and no systematic contemporary studies were conducted. The
sea otter, which has the densest fur of any animal, narrowly escaped the fate of the sea mink. The discovery of large populations in the North Pacific was the major economic driving force behind Russian expansion into
Kamchatka, the
Aleutian Islands, and
Alaska, as well as a cause for conflict with
Japan and foreign hunters in the
Kuril Islands. Together with widespread hunting in California and British Columbia, the species was brought to the brink of extinction until an international moratorium came into effect in 1911. Today, some mustelids are threatened for other reasons. Sea otters are vulnerable to
oil spills and the indirect effects of overfishing; the
black-footed ferret, a relative of the
European polecat, suffers from the loss of American
prairie; and
wolverine populations are slowly declining because of
habitat destruction and persecution. The rare
European mink (
Mustela lutreola) is one of the most
endangered mustelid species. The
ferret, a domesticated European polecat, is a fairly common
pet. == Evolution and systematics ==