[LEPS-L:8048] Re: Extinct 'species'

[Chris J. Durden]

>Date: Thu, 30 Nov 2000 10:12:06 -0600
>To: gochfeld at EOHSI.RUTGERS.EDU
>From: "Chris J. Durden" <drdn at mail.utexas.edu>
>Subject: Re: [LEPS-L:8045] Re: Extinct 'species'
>In-Reply-To: <3A264DA1.AAADF7F6 at eohsi.rutgers.edu>
>References: <sa24dfa0.049 at smtp1.cdfa.ca.gov>
>
>This points out the necessity to keep looking for even the most unlikely
"probably extirpated" species because, like the Coelacanth it may
re-appear. This approach requires some humility. We must realize that we
are not perfect observers or collectors and some wily species may manage to
elude us for decades. It also points out the value of serendipetous
research or unplanned observations made on the fly when conditions are just
right and we can "sieze the moment". It is impossible to obtain funding or
permitting for such serendipetous research these days because the
regulators have the upper hand. Today serendipetous observations will be
unsupported by voucher specimens and the reports will be regarded with
scepticism, or if vouchered (even by blood sample or dental impression,
taken from a released individual) and believable the observations will be
made by outlaws. This is a ridiculous situation that we would have laughed
at 50 years ago. It is a sad situation too. In our ignorance we no longer
expect the Ivory Bill Woodpecker show up so we lack incentive to preserve
potential habitat and we do not even pay attention if we hear its call,
dismissing the sound as a recording played by some smart aleck across the
woods.
>............Chris Durden
>
>At 07:52  30/11/00 -0500, you wrote:
>>> Doug concluded:  so the lack of new records is not necessarily
convincing evidence of extinction. PROVING that anything, even a large
vertebrate, is extinct is (as those in Tasmania can attest) nearly impossible.
>>
>>This reminded me of Popper's black swan idea (I don't know whether it is
a theorem or a law or what), namely, that no matter how many white swans
you count, you can never prove that "all swans are white", but you only
need to find one non-white swan to disprove that statement.
>>
>>That's why in science we don't try to "prove" our hypothesis, rather we
pose null hypotheses which we try to reject, recognizing that if we reject
the null hypothesis it provides support for, but does not prove our
underlying or alternative hypothesis.
>>
>>So we CAN'T prove that something is extinct, but we can gain confidence
from repeated negative surveys that it is NOT LIKELY TO EXIST (I suppose).
>>
>>For example, The USFWS has tried periodically to mount evidence for
declaring that the Ivory-billed Woodpecker is extinct, so it can be removed
from the endangered list. But since there have been few (or no, depending
on your degree of skepticism) confirmed sightings in recent decades, people
don't bother to look for it in places where it used to occur.
>>
>>So it's heartening to know that the borer has been re-discovered.  In NJ
the Arogos Skipper has been rediscovered after 20 years, but prior to that
we hedged its status as "probably extirpated", although in retrospect, it
was a species that had been unrecorded for many years and so may actually
be an erratic colonist.
>>
>>M. Gochfeld
>>
>>
>>
>>
>>  


 
 ------------------------------------------------------------ 

   For subscription and related information about LEPS-L visit:

   http://www.peabody.yale.edu/other/lepsl