Bob's points are well taken, but they do seem to put us on the horns of a
dilemma.  On the one hand, our conclusions must be stated with great
circumspection given the difficulties with the data sources that we have.
So clearly we need better data sources.  But, on the other hand, if we wait
to draw conclusions until we have the kind of data that we might desire, the
conclusions at that point may well be that various species of interest are
extirpated.

My guess (and hope) is that Audubon scientists did the best that they could
with the data that they had because to wait for better data would simply be
to miss the problems that we all think are, in fact, occurring.

Kind of reminds one of the climate change debate.  The strategy that
skeptics first adopted was to claim that the data was insufficient to
support the (then tentative and qualified) conclusions.  Now that "good"
data has been amassed and consensus about the reality of the effects has
been achieved, these same skeptics now claim that it's too late to do
anything about the problem and we should learn to live with it!  Substitute
"decline of species" for "climate change" and you'll get the idea.

Note:  I am *not* attributing "obstructionist" motives to Bob, just pointing
out the larger issue:  we are, to some extent, in a "damned if you do,
damned if you don't" situation.

Bill Heck



On 6/17/07, Bob Powell <[log in to unmask]> wrote:
>
> On 6/17/07, Bill Whan <[log in to unmask]> wrote:
> >
> > Guess nobody had any thoughts to share on Audubon's lists of birds in
> > decline.
> >
>
> Well, I was going to reserve my comments until I have read the full
> report,
> but the demands of atlassing may mean that it will be sometime in late
> July
> before that happens.  In the meantime, here are a few first impressions.
>
>
>    1. The Christmas counts and the breeding bird surveys are strike me as
>    very blunt instruments for producing continental population estimates
> no
>    matter how sophisticated the statistics are.  The sampling issues alone
>    would be enough to shoot down the conclusions.  The CBCs are also
> notorious
>    for their lack of uniformity of level of effort.  Some are done by one
>    observer, some by 300.  Neither have any standardization or training
> for the
>    observers.
>
>    2. There seems to be little or no compensation for covariates, such as
>    the changes in land cover and land use, changes in weather patterns,
> etc.
>    There seems to have been little use of the wealth of GIS and remote
> sensing
>    data out there.
>
>    3. No confidence intervals are given.  I recently attended a workshop
>    on distance sampling in which two regional (not continental) population
>    estimation studies were presented.  Both were done with the latest and
>    greatest techniques for compensating for the probability of detection
> and
>    both were done with excellent stratified random samples.  In both cases
> the
>    confidence intervals were huge.  Both of them concluded that in order
> to
>    detect a significant population change with good accuracy would require
>    replicating the surveys every year for about 20 years.
>
>    4. I am skeptical of the mesh on the time scale.  From the New York
>    Times account it sounds as if their trend analysis is conducted on just
> two
>    data points separated by 30-40 years.  That misses out a lot of
> structure.
>
>    5. I note that the report was not properly peer-reviewed.  By
>    self-publishing, NAS has done an end run around that process, though
> they
>    claim to have had some sort of private peer review.  No fair.
>
>    6. By going big with a poorly-designed study, NAS may be doing more
>    harm than good.  Those who oppose conservation measures will have been
> given
>    more material with which their hired biostitutes can assail
> environmental
>    groups for pushing "poor science."  I am a veteran of two such
> campaigns
>    (Prince William Sound and the Everglades) when we came under heavy fire
> from
>    special interests when the science was actually outstanding, as
> subsequently
>    proven by peer review.
>
> But as I said, I haven't read the report yet.
>
> Cheers,
>
> Bob
>
> --
> Robert D Powell
> Wilmington, OH, USA
> [log in to unmask]
> http://rdp1710.wordpress.com
>
> Nulla dies sine linea
>
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--
Bill Heck

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