NABA 4JC
Michael Gochfeld
gochfeld at eohsi.rutgers.edu
Wed Mar 31 03:11:52 EST 1999
The NABA 4th of July counts are patterned for better or worse on the
Audubons Society Christmas bird counts, hence the 15 mile diameter
circles. Those counts began about a hundred years ago. There is now a
substantial literature on the strengths and limitations of extracting
"scientific" information from those counts. With appropriate caveats
they have proven quite useful in a number of respects. There are also ,
breeding bird census routes which were scientifically designed to
sample bird populations in a repeatable fashion, but these too have
their limitations.
Ann Swengel has published a number of concise reports (back
cover of NABA's "American Butterflies") intepreting the 4JC data for
species such as the Monarch (readily identified by almost all
participants). I think one should assume that like any data there are
quality questions, but that the sheer mass of data, and the long term
trends they document, makes them worthwhile. Butterfly censusing is
more vulnerable to phenology and weather than bird censusing, but
attempts to make counts comparable from year to year, are being
encouraged.
M. Gochfeld
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