"....The truth is out there."
-- Dr. Jerome Jackson, 2002 (... & Agent Fox Mulder)
“There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.”
"All truth passes through 3 stages: First it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident."
-- Arthur Schopenhauer
Tuesday, March 21, 2006
-- Ponder Condors --
John Nielsen's wonderful book, "Condor" recently appeared in bookstores detailing the efforts to bring that bird back from the brink, and it affords me a sort of follow-up to the previous post: Those who remember the tremendous controversy surrounding the California Condor recovery program when it was first proposed know that it largely split both the conservation and birding communities down the middle between those who supported the project and those who felt the Condors' fate was hopeless and they should be allowed to die out naturally flying free out in the wild, rather than dying ignominiously behind wire bars in some Calif. research facility. I was in that latter camp (and in some mighty fine company I might add). But with hindsight I was wrong. Even if the project eventually fails (ultimate long-term success is still uncertain), what has been learned in the process will no doubt be invaluable in some future circumstance, and the success to this point has been quite remarkable. It is good that the project went forth, and personally I don't ever again want to give up prematurely on a species due only to scarcity of hope (I don't mean for this to imply, however, that I think a captive breeding program for IBWOs could succeed). Species extinction is a terribly serious matter, not to be taken lightly. So again I'll reiterate, it is not simply a desire to be right on this subject (Ivory-bill existence) that so drives the passion many of us feel in the debate... but rather, deep down, it is our profound fear and unwillingness to chance being wrong (if we were to adopt the opposite stance). And thank goodness I was wrong about the California Condor.
It's theorized that the Condor fed on the massive dead mammals of Ice Age and prior eras and was originally much more widespread. Ivorybills presumably were already pretty well inbred when Tanner came upon the 7-10 birds in the Singer Tract. Yet their reproduction was as successful as a Song Sparrow. They lay fewer eggs, of course so their overall replication rate is/was lower.
I'm not a geneticist so I can't
really say how inbred 15 California Condors were prior to their rescue in 1988.
Despite some harsh comments about
Mike/Fishcrow's methods and evidence, there have been a few good frames showing white trailing edges and in general, a big-head and shoulders about the bird that
warrants closer examination and
As far as his 3 Connecticut Warblers in one day... get out your C. Bent warbler book from 1930 and read about how it used to be found in the parks
on the East Coast near the Cambridge, MA area, and how there were small flocks of these
some years in fall migration. I have seen 2 of these birds myself in fall migration on separate days on the Hudson River flyway.
I have heard similar things said about the current Whooping Cranes and that they are an extremely inbred lot. I have not heard of any major problems associated with that genetic bottle neck in them. Birds may be affected less by inbreeding than some mammal species, read below.
I can personally tell you that severe inbreeding in both domestic and wild rabbit species does, after a time, affect them in a negative way. Most typically it manifests itself as lower fertility rates, smaller litters, reduced disease resistance and smaller overall body size.
Then they were of course, dismal.
The last recorded IBWO fledgling was in 1941. Either she died, or she was the "last bird" seen in 1944. So presumably she could have lived a few more years, making the 1944 extinction date a little shaky.
Tanner did a lot of hunting for this bird at at time when old growth swamp was hemmed in on all sides and there was little if any second growth.
I never saw a Pileated Woodpecker as a child growing up in an apple orchard but as planted trees became old and decayed, people began to see Pileated Woodpeckers in very suburban settings.
We may now have IBWOs nesting in small tracts of virgin habitat and ranging more widely over second growth. Second growth didn't exist
until some farmland was abandoned or timberland grew back. So in Tanner's time any surviving IBWOs were in some deep dark places that he might have missed.
I bought his book and saw the miles this man racked up to explore the most promising areas.
But he didn't get to all parts of all river bottom forests. And if an area was not a known nesting area by the late 19th Century, he often skipped over the area or took a cursory look. You have to wonder if it wasn't a bit depressing to keep looking and looking and finding nothing except the doomed Singer Tract birds and some in S. Carolina (and one he just missed in Florida in the 30s).
I haven't learned much about his
searches later in life though he was still quite a hiker in his 60s.
I wonder how many southern counties/parishes are not represented in CBCs or Breeding Bird censuses?
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