Figure 1. A nutria is three times the size of a muskrat and its
tail is round, not flattened vertically, as is the muskrat’s.
Nutria and beaver are similar in size, but the beaver has a
large tail, which is flattened horizontally. (Photo courtesy of
a homeowner on Lake Washington.) Nutria (Myocastor coypus, Fig.
1) are semi-aquatic rodents native to southern parts of South
America. In the 1930s, they were sold throughout North America
to fur farmers and as a means of controlling unwanted aquatic
vegetation. Various associations, magazine and newspaper
articles, and demonstrations at county fairs promoted the sale
of nutria in Washington. More than 600 nutria farms existed in
Oregon and Washington from the 1930s to the 1950s. Flooding and
storms damaged holding structures, allowing nutria to escape.
Farmers also released their stock when nutria farming became
uneconomical. By the 1940s, nutria had been captured by trappers
on both sides of the Cascade Mountains in Washington. Adult
nutria average 24 inches lon