After having started all this, I had better add that CBCs have provided a
wealth of information for all sorts of published studies, from cyclic and
noncyclic population changes in single species to latitudinal gradients in
winter bird diversity and abundance. I saw the value of CBCs when I did a
college paper for a population biology class by analyzing 5 years of counts
for some species that varied from year to year in southeastern U.S. Was I
amazed when, after all the mathematical analysis, I found that the mean #
of Downy Woodpeckers/100 count hours throughout the southeast (i.e., on the
counts I analyzed) varied by only about 0.1 over the 5-year period! Some
of the other species took a precipitous, tremendously obvious and
significant dip the year after a very cold winter over much of the area,
and a detectable rise in the year immediately following. I was sold on the
idea that these were a very powerful source of data indeed, primarily
because the true "signals" couldn't be destroyed even by the amount of
"noise" introduced by the sloppy counting methods I mentioned yesterday.

The only reason I mentioned them was because both the CBC season and the
stories were fresh in my mind (and I've actually heard some even worse
anecdotes by word of mouth since I wrote my comments) and I wondered about
the experiences of others. I suppose no one will be posting a message
explaining how sloppily they compiled, led, or participated in a count, so
the responses will certainly be a bit biased toward "we do a good job on
our count."

It's a shame Terry Root's book (Atlas of Wintering North American Birds)
was so flawed in execution, as Chris Hill mentioned, because if it had been
done as well as it might have, it would really be of great value as an
indicator of winter bird distribution in the U.S. and southern Canada. For
example, see Terry Wahl's review of it in WASHINGTON BIRDS Vol. 2, where he
points out how flawed it is at the level of Washington state.

My suggestions would have been to use a single map for each species, with
shading rather than the difficult-to-understand mountain peaks and
concentric rings, and a way to show all records, at least as dots. In
addition, a large number of species were considered "problems" because of a
variety of difficulties in analyzing the data, and species seen at fewer
than 40 sites weren't mapped at all. Finally, by looking at her maps, it's
amazing to see how many birds are obviously misidentified. Swainson's
Thrushes, which winter from Mexico south, had a rather extensive winter
range in the U.S. according to her map.

One thing that hasn't been mentioned in some of the reviews of her book is
the text material for each species, actually quite interesting and
containing a basic natural history for each species. The book is worth
having for this reason, because the maps do convey much interesting
information, and for its introduction.

Dennis Paulson phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416