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Today, re-running an entry I posted here over 10 years ago!
Recently
Mark Michaels linked to an older Geoff Hill review of a Noel Snyder
monograph where he [Snyder] argues that hunting played a much greater
role in the demise of the Ivory-bill than generally recognized (definitely
worth reading):
http://www.bioone.org/doi/pdf/10.1525/cond.2008.8658
I
made the same essential argument here a decade ago (in a different post), and to
give people their due, Mike Collins made a similar argument as far back
as 1997. At the time I utilized this quote from T. Gilbert Pearson, one of
the foremost naturalists of his day:
"The reduction in
abundance of this species [IBWOs] is due most probably to persecution by man, as
the species has been shot relentlessly without particular cause except
curiosity and a desire for the feathers or beaks." (National Geographic
Magazine, April 1933)
The reason I bring it up
now is to again reiterate my belief that very little that is
concluded in the literature about the behavior or needs of Ivory-billed
Woodpeckers, based on Tanner's work, can be
assumed true for
currently surviving IBWOs. I don't even believe Tanner's conclusions for
the Singer Tract birds automatically generalizes to any Ivory-bills that then
survived in Texas, Florida, South Carolina, or elsewhere -- we just don't know --
the sample size, studied largely by a lone individual, is simply too
small to be very meaningful (p.s., I DON'T blame Tanner for this; it is
common practice in field biology to draw over-reaching conclusions from
inadequate sample-sizes -- nor do I mean to imply that the historical studies lack any merit, but only that they must be viewed cautiously, instead of as gospel fact).
Anyway, here's what I wrote, more generally, back in 2005, in the post "
Science and Sample Size":
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One
of the fundamental tenets of science methodology concerns having
adequate sample sizes from which to draw conclusions/generalizations. In
the years since James Tanner's dissertation on the Ivory-bill (based on
but a handful of birds), notions that Tanner himself often recognized
as tentative became hardened into unchallenged dictums without a good
basis for doing so. There is in fact little
that can be stated with certainty about the Ivory-bill's diet,
behavior, habits, or requirements for survival, even though such
statements are rife in the literature. (If one were to intensely study a
dozen people and then write a report generalizing to the entire human
species the weakness would be readily apparent.) This is all especially
true given that any Ivory-bills still around today may in fact have
survived specifically BECAUSE they came from individuals with
significantly DIFFERENT characteristics/behavioral traits from their
brethren, which increased survivability for themselves and their
offspring. At least Tanner got it right at the end of his original
introduction:
"The chief difficulty of the study has been that of drawing conclusions from relatively few
observations... My own observations of the birds have been entirely
confined to a few individuals in one part of Louisiana... the
conclusions drawn from them will not necessarily apply
to the species as it once was nor to individuals living in other areas.
The difficulty of finding the birds, even when their whereabouts was
known, also limited the number of observations. Especially was this true
in the non-breeding season. With these considerations in mind, one must
draw conclusions carefully and with reservations." (italics added)
The
problem with our knowledge of Ivory-bills is not simply how little we
know, but rather how much we think we know that might just be utterly
wrong for any birds remaining today...
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