This map layer portrays our current understanding of the distributions of
United States and Canadian bat species during the past 100-150 years.
Specimen and capture data were obtained from a variety of data sources,
including U.S. State natural heritage programs, Canadian conservation data
centers, published literature, unpublished reports, museum collections,
and personal communications from university, federal, State and local
biologists. Records are all specimen, roost, capture, or positive visual
identification-based; no acoustic-only identifications were used for this
map layer. This map layer reflects minor changes to the July, 2002, data
set.
