>Re Jennifer Seavey's BTPI discussion:
>
>Yeow, she wasn't kidding. Here are the BBS trends for WA and OR:
>
>State Period Trend n sig.
>OR 1982-1991 -14.7 19 p<.01
>OR 1966-1991 -3.2 21 p<.01
>WA 1982-1991 +.7 21 none
>WA 1966-1991 -3.5 23 p<.1
>
>The trend is expressed as % annual change using a formula similar to that
>for calculating compounding interest. n is the number of BBS routes from
>which the trend was calculated. The authors warn against using data for
>species where n<14. p is the significance of the trend, from testing the
>hypothesis that the trend is actually 0. The source is an untitled,
>unpublished report from Bruce Peterjohn for USFWS/NBS biologists.
>
>____________________________
>Mike Smith
>
And Mike SMith's and Dennis Paulson discussions

>Hmmm, maybe a few more words are needed here. Yes, it's clear that pigeons
>have declined in Oregon, but it's anything but clear that they've done so
>in Washington. A p of <0.1 is not considered particularly significant in
>science (people prefer 'p's <0.05 or less for most statistical tests), so
>the 1966-1991 decline is "not particularly significant." The decline in
>Washington in the last decade--presumably what should concern most of us on
>this list--is *not* a decline.

>A little hypothesis testing was in order: I just checked BTPI totals for
>he Seattle Christmas bird count for two 10-year periods, 1963-72 vs.
>1983-92. Average per count 78.7 (range 2-182) vs. 145.0 (20-495).
>Hypothesis of decrease *rejected.* Party hours increased between the two
>intervals, but not that much (138 in 1972, 180 in 1992). If anyone wants
>to do a similar analysis for another Washington CBC, be my guest. We can't
>do the same thing for Oregon, because, as I wrote before, they don't seem
>to hang around for Oregon CBCs!

>I have already seen several reports in which BBS data were used to make
>generalizations about massive bird declines when in fact further assessment
>casts doubt on such conclusions. We should carefully monitor populations,
>and even err on the side of caution when interpreting data, but let's stay
>credible.

>No offense to Jennifer or Mike intended by my response, and thanks for
>giving us some quantification of what is otherwise a bunch of subjective
>impressions. But my subjective impression is still that BTPIs haven't
>declined obviously in western WA since I've lived here.

>Another hypothesis: we're feeding pigeons more in Washington, and the
>Oregon ones have heard about it.....

>Dennis Paulson, Director

___________________________
Dennis has raised some really good points about how we should use caution in
using existing data. The same comments were made by many during the last
iteration of the neotropical migrants discussion. And there was also some
comment on the conflicting studies on forest health and the need to cut. Very
valid points.

However, one can't help but notice that our environment in both urban and rural
areas is changing rapidly. While we can see habitat destruction, it's very hard
to get concrete, scientifically valid data on species declines until it's almost
too late. So the dilemma is, "Should we use questionable data to raise warning
flags and possibly be exposed as 'crying wolf,' or should we call for more
studies (Dennis, I am definitely not implying you think this) and watch the
habitat disappear while more information is collected." After ten years of
working directly in the environmental field I don't have any answers. I would be
curious to hear your opinions.

What I do know is that as a bird watching community we have a tremendous amount
of collective knowledge. We have to find a way to harness that knowledge and
anecdotal evidence to preserve habitat for all the critters we care about. Even
in the absence of definitive studies, warnings and concern should be raised.


Enough ranting, time to get off the soapbox; I'm going birding!

Mike.Scuderi at internet.nps.usace.army.mil