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In his seminal Ivory-bill study, James Tanner concluded that the two most significant factors in the species' demise were habitat loss and hunting... and the latter ran a distant second. However, in actuality, habitat loss does not itself kill birds, it simply leads to other factors that cause birds to die over time (increased predation, starvation, competition, exposure, failure to thrive or reproduce). Hunting on-the-other-hand kills birds immediately (even the wounded are generally doomed, as well as any progeny that would have arisen therefrom). Put another, more stark way, creatures have some opportunity to adapt to habitat loss (as MOST all species sharing the Ivory-bill's habitat DID!); they don't however generally adapt to bullet wounds!
Through the 19th and early 20th centuries hunting, for food, recreation, and commerce, was a routine part of every male's life (especially throughout the south). We probably forget today just HOW ROUTINE! I believe the impact of hunting on this species' population could be vastly underestimated (not to diminish the importance of habitat loss, but to say it was not so singular in its role, and that its impact was quite different from hunting).
When sharing any area traversed by Man, the Ivory-bill was likely one of the most large, conspicuous, and TEMPTING avian targets in the woodland. It would have been extremely vulnerable (as well as its eggs, in a day of widespread "oology" or egg-collecting), returning predictably again and again to the same feeding, roosting, and nesting trees. In fact, one could imagine that virtually EVERY single Ivory-bill EVER crossing paths with an armed human in earlier days may have been shot at for food or recreation, so alluring a target it would've been. The impact of such victimization on the entire species is impossible to measure, but given the birds' relative scarcity, conceivably may have been devastating (the Pileated, having a much greater population and range to begin with, could have suffered even higher losses, with little impact on that species as a whole).
Some may wonder what difference it makes today, how the bird became so rare; all that matters is that it is rare. But it matters greatly. If hunting's impact has been hugely underestimated then the removal of hunting pressure (illegalization) on the species around Tanner's time, could have afforded any remaining population an immediate opportunity for stabilization. Tanner estimated there were less than 30 Ivory-bills left in the entire South at the time of his study, but others believed the number was closer to 200, or even more. For Ivory-bills to persist at all today, the latter estimates were likely closer to the truth. With increases in 2nd/3rd growth forest across the decades (and new forest management practices), potential IBWO habitat has slowly grown over time lending any survivors a chance to hang on. But to whatever degree hunting's impact was major, its abolishment 60+ years ago will have boosted that chance MULTI-FOLD.
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2 comments:
"When sharing any area traversed by Man, the Ivory-bill was likely one of the most large, conspicuous, and TEMPTING avian targets in the woodland. It would have been extremely vulnerable (as well as its eggs, in a day of widespread "oology" or egg-collecting), returning predictably again and again to the same feeding, roosting, and nesting trees."
If such a large, conspicuous, predictable bird still survives in this country, how can we explain our 60+ year span without a single confirmable record of the bird? Please see more at:
http://tomnelson.blogspot.com/2005/08/just-how-wary-was-ibwo.html
Few individuals, and even fewer birders, ever venture into the sort of habitat any remaining IBWOs may reside in. In an earlier time it was routine for people not only to venture into such areas, but indeed to live in them.
There has only been one really organized, well-done IBWO search in the last 60 years -- at Pearl River -- and even several of those folks felt their effort was inadequate. Tanner's search, Jackson's, and all others have been wa-a-ay too limited in both manpower and time-expended at various locales. Yet, despite that, there have been dozens of non-dismissable sightings over the decades. A "CONFIRMABLE" sighting, requiring photographic evidence, will always be hard to come by -- indeed I would have difficulty getting indisputable photographic evidence of Cardinals in my own back yard (have you ever tried to capture one on film AND prove where the shot was taken?)
Finally, 60 years is not really a long time; several species have gone 100 years or more before being rediscovered (in a confirmed way)... and then there's the Coelecanthe (fish) which was presumed extinct for millions of yrs. before re-discovery!
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