At 03:23 PM 12/6/98 -0800, sanjer at televar.com wrote:

>I have been wondering about something--could someone enlighten me?
>
>On the NAS statement about the CBC under the title "WHY" they say "Birds
>
>are indicators of the overall health of our environment. Christmas Bird
>Count data over time in any given area can provide valuable insight into
>
>the long-term health of bird populations and the environment".

The key terms are "insight" and "long term", I think. CBC data can
provide insight into gross trends, for instance the spread westward
of starlings in past decades, the urbanization of crows, the decline
of bluebirds, etc. It can also provide some gross information on
population trends for particular species over large areas over time.

That's about it, though. It's value lies in the fact that it is the
one and only such nationwide winter census that exists - informal or
not, it's much better than NO census effort.


- Don Baccus, Portland OR <dhogaza at pacifier.com>
Nature photos, on-line guides, and other goodies at
http://donb.photo.net