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June 2007

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From:
Bill Whan <[log in to unmask]>
Reply To:
Bill Whan <[log in to unmask]>
Date:
Sun, 17 Jun 2007 19:05:03 -0400
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  The Ohio bird list Jim McCormac offers off-list merely repeats what I
posted here the day before yesterday. The forum suggested, where nothing
had appeared for over a week, seems a poor place to discuss it. In fact
I can't see anything faintly resembling a discussion on that forum for
the past two months. Among the stated purposes of this list is to
"discuss and debate the occurrence, distribution, identification, and
ecology of Ohio birds," so let's get to it.
        As for the first of Bob's interesting remarks, does anyone know where
the "full text" of this study can be read? Has it been published? What
exactly would a peer reviewer have to work with? Right now it seems to
exist in drafts and press releases.
        I agree with Bob that the CBCs lack many of the rigors of the BBS
methodology. But if you want continent-wide data for the past 40 years
you have to use the CBCs somehow, or go with the Breeding Bird Survey
alone, which falls short at least on Bob's second objection: it surveys
the same areas year after year, even after they become parking lots.
        The list of the most diminished Ohio birds involves only local
breeders, birds that mostly winter elsewhere, and you wonder how the
Christmas Bird Counts played much of a role in this status. Most of
these species don't show up on Ohio CBCs.

OHIO:  Northern bobwhite  -99%    N. AMERICA:  Northern bobwhite -82%
        Grasshopper sparrow  -99%      Evening grosbeak -78%
        Vesper sparrow  -91%           Northern pintail -77%
        Henslow's sparrow  -85%        Greater scaup   -75%
        Green heron  -82%              Boreal chickadee  -73%
        Cerulean warbler  -80%         Eastern meadowlark  -72%
        Red-headed woodpecker  -78%    Common tern    -70%
        Eastern meadowlark  -75%       Loggerhead shrike  -70%
        Bobolink  -70%                 Field sparrow  -68%
        Hairy woodpecker  -68%         Grasshopper sparrow  -65%
        Northern flicker  -67%         Snow bunting  -64%
        Bank swallow  -64%             Black-throated sparrow -63%
        Red-winged blackbird  -64%     Lark sparrow  -63%
        Yellow-breasted chat  -63%     Common grackle  -61%
        Savannah sparrow  -62%         American bittern  -59%
        Acadian flycatcher  -61%       Rufous hummingbird  -58%
        Eastern wood-pewee -60%        Whip-poor-will  -57%
        Field sparrow  -59%            Horned lark  -56%
        American redstart  -58%        Little blue heron  -54%
        Prairie warbler  -54%          Ruffed grouse  -54%
        Great crested flycatcher -52%
                Only four of Ohio's--bobwhite, Henslow's, the meadowlark, and field
sparrow appear on the continental 20. You wonder why the cerulean
warbler, which here in the heart of its range is said to have fallen by
80%, doesn't appear on the continental list; has it really declined more
steeply in Ohio than elsewhere? Common grackle ranks #14 on the
continental Top 20 (-61%), but is missing on Ohio's list; is Ohio some
kind of stronghold where it's declining more slowly than elsewhere?
        I am unqualified to critique the statistical methods used to arrive at
these lists. Still, I wouldn't expect the lists to present  many
surprises to a lot of people who read these words, folks who spend a lot
of time in the field studying birds. But maybe they do. One bias is the
short term of the study--only 40 years. Many birds--several have
mentioned evening grosbeak--may have fluctuated radically on a longer
cycle, and if a different recent forty-year period had been chosen would
have ranked as sharply increasing. As someone mentioned, wild turkeys
rank first in numbers gained recently, but they are still probably less
numerous than they were 200 years ago.
        One interesting comment made by several is that the presentation seems
one-sided. Why not emphasize as well the large (perhaps larger) number
of species whose numbers are increasing? Why not point out where the
local diversity of bird species is increasing? Ohio has a lot more birds
that rate as common now than we did 200 years ago. I don't mean to make
light of declines in the numbers of certain species, but I do keep a
careful eye on the rhetorical use made of such declines. Some apparent
changes are more troubling than others. Nobody knows much about why
loggerhead shrikes are disappearing, but it's not hard to come up with
plausible reasons for the decline of bobwhites. Falling horned lark
numbers are harder to explain than those for meadowlarks. Mere
habitat--at least as we understand it--doesn't seem a panacea for these
losses. What do others think?
Bill Whan
Columbus

Jim McCormac wrote:
> Hi all,
>
> In tandem with the National Audubon report, Audubon Ohio also released a
> list of the top 20 species that have declined in Ohio. Another interesting
> compilation. I've posted it over at the Ohio Birds Forum, which is a better
> place to accommodate an open-ended discussion like this. Have a look at the
> list, and share your thoughts.
> http://www.ohiobirds.org/forum/viewtopic.php?pid=1123#p1123
>
>
> Jim McCormac
> Columbus, Ohio
>
> -----Original Message-----
> From: Ohio birds [mailto:[log in to unmask]] On Behalf Of Bob
> Powell
> Sent: Sunday, June 17, 2007 1:57 PM
> To: [log in to unmask]
> Subject: Re: [Ohio-birds] Audubon "Birds in Decline" report
>
> 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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