A digital GIS update to the classic Ulbrich 1930 map of muskrat (Undatra zibethica) population range expansion in Central Europe

This dataset is a digital version of a seminal dispersal data set of muskrat spread in Central Europe. We obtained and scanned an original copy of Ulbrich (1930), creating a digital image file, which we then geo-referenced in Arc Gis 10.2. The data herein contains metadata explaining the conversion process, necessary images to geo-reference the map, reference points used to "fix" the dispersal map to a map of present-day Europe, intermediate files (points and polygons produced when tracing the population ranges), and the final spatial dataset.

Reference to the original data:  Ulbrich, Johannes.  1930.  Die Bisamratte; lebenweise, gang ihrer ausbreitung in Europa, wirtschaftliche bedeutung und bekampfung.  Heinrich, Dresden.