# dots on maps

[Panza, Robin]

I have rejoinders or warnings to both points made by Steven Clemants.  I
agree that, at some scales, a grid can be more useful than dots.  For larger
scales, such as species distributions across a country, distribution of
races/subspecies/variants, or distribution by habitat, dot-oriented maps
make more sense than grids.

His second point, the lack of need for vouchers, is also one of scale. Yes,
the breeding bird atlases have been successfully constructed by song, and
museums certainly don't need cardinal vouchers from every county in
Pennsylvania. However, *anything* unusual, range edges, or taxa difficult to
distinguish must be accompanied by vouchers or the data is suspect.  Many
invertebrate taxa cannot be identified in the field, and even vertebrates
can be problematic.  Chipmunks in the Sierra Nevada of western US are
altitudinally separated, but they cannot be identified without skull
characters.  Without vouchers, one can only *assume* that a chipmunk seen is
of the species that's "supposed" to occur there.

Robin

Robin K Panza                           panzar at carnegiemuseums.org
Collection Manager, Section of Birds      ph:  412-622-3255
Carnegie Museum of Natural History        fax: 412-622-8837
4400 Forbes Ave.
Pittsburgh  PA  15213-4080  USA