Becca Knox wrote

> David G. Campbell suggests in his book "The Crystal Desert" that Wilson's
> Storm Petrels may be the most abundant bird in the world - untold numbers
> live in both the arctic and the antarctic as well as the oceans in
> between.

> While birding around Australia, my husband and I often speculated over
> relative abundance - are there more magpies or house sparrows in
> Australia? More budgies or more red-necked stints? It's a fun game but
> one that you never really can tell the answers to. Are there more
> starlings or more crows in Seattle? More house cats or more squirells?

Well, you may not be able to get definitive answers, but this seems like
a great subject for some Fermi calculations. Fermi always said that by
using their ordinary knowledge and common sense, people should be able to
make reasonable estimates of many things that you would think are
unknowable. We ask our students in basic science programs here to make
Fermi calculations all the time: How many piano tuners are there in
Seattle? How many grains of sand are there in the Sahara Desert? How
much rubber is worn off tires every year in the U.S.? In some cases, of
course, you can check up on your estimate (with the Seattle phone book,
for instance) and determine if your reasoning is good. The idea is to
work toward good order-of-magnitude figures, and you rarely hope to do
better than getting a reasonable power of 10.

So for birds, the calculation is something like: estimated numbers seen
per unit test area times the estimated number of those test areas. For
House Sparrows, perhaps one estimate for urban areas and another for rural
areas. But it could be done. It would be fun, in fact. Has anyone ever
fooled around with such calculations? A good breeding bird atlas might
contain the essential information, or it might be a source for a reality
check after you've made your own estimates.

Burt Guttman guttmanb at elwha.evergreen.edu
The Evergreen State College Voice: 360-866-6000, x. 6755
Olympia, WA 98505 FAX: 360-866-6794