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If Ivory-billed Woodpeckers were simply hanging out in remote and very restricted territories they would've probably been found by now and fully documented. The alternative, that many have suggested, is that they are ranging over large swathes of territory, and not restricting themselves to a given area. But I've also argued that the farther afield they routinely fly, the MORE sightings we should have by now, given the wide casting of searchers over the last four years (i.e. the more ground the birds cover, the greater the chances of human encounters).
But why would the birds even move about so much? Some surmise the constant search for new food resources keep them nomadically moving around; that would make sense if their numbers were great enough that they truly cleared out food resources of any given area in short order, but I don't believe that to be the case. I suspect the numbers are so paltry low that they could sustain themselves in a given area for a significant length of time (the fewer the birds, the fewer the resources required). Perhaps frequent human disturbance causes them to keep moving on. Or maybe it is the search for mates that constantly drives them to new grounds (of course they must have had enough success finding mates over the last 60 years to still be with us at all, and when they do locate mates their movement would likely then be constrained at least through the breeding season).
If Ivory-bills are both looking for mates AND actively trying to avoid human encounters, that combination might account for their movements and elusiveness; this in turn largely assumes we are dealing primarily with juvenile and unmated birds at this point... and maybe we are. Given the paucity of sightings though, can there even be enough of them to find mates with regularity needed to sustain the species going forward? Finding an active nesthole is key to this whole story in so many ways, including getting the clear photos/film sought, and documenting that the birds are breeding, as well as studying the breeding process itself. Finding a nesthole... keeping its locale top secret, but broadcasting its activity via remote videocam over the internet with moving pictures reminiscent of Singer Tract film a la 70 years ago... ahhh, a jaw-dropping prospect to be devoutly wished!
I continue to believe that for the above scenario to play out the birds must travel along wooded river corridors (where there may be diminished chance of sightings), with the Mississippi River itself, and its tributaries, offering the most obvious possibilities as it stretches from western Tennessee/Illinois along Arkansas, Louisiana, and Mississippi. And Florida with its multiple interconnected swamps and waterways stretching from the central part of the state, northward and westward, likewise retains interest. Alabama, Georgia, South/North Carolina, Texas... don't seem (to me) as riveting, nor as readily able to account for 60+ years of evasiveness. But... in the Ivory-bill arena, little can be taken for granted.
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14 comments:
You need to spend a week in the swamps; after that you will be far less convinced that we should have already found a few flying needles in a 10,000+ square mile haystack. You, like most of the skeptics, are again vastly overestimating the effectiveness of birders as bird finding devices and vastly underestimating the scope of the challenge.
As for Geography -- South Carolina has an enormous network of riparian swamps in multiple watersheds; most of these watersheds are interconnected by forest corridors along the lower coastal plain flatwoods. Its territory is at least as inviting as Florida's, and there are a lot fewer birders. Georgia likewise has some very extensive, and virtually unsurveyed, systems of river swamps. Georgia has far more 20th Century Ivorybill reports than AR did before 2004, and there is good evidence that Ivorybills persisted there into the 1940s, later than the Singer Tract birds. Remember, also that there had been squat from the upper MAV (TN/AR/IL) in forever; indeed TN doesn't have one single firm historical record and the species is not even on the official state list as ever having been documented. AR was only slightly better off, and look what happened there.
What Bill said, and the only swamps I've been in within memory bordered some spring creek trout streams up in Idaho (Silver Creek and Henry's Fork of the Snake, just to tweak the fly fishers' envy bones). Getting around in them is a hassle bordering on insanity, and as soon as you introduce a boat or other watercraft, then the stealth factor diminishes every time you make a move.
It's usually "huntin' sorts" who frequent such environs, and their attention is focused elsewhere, of course, even if their quarry is ducks. And come to think of it, a big bird with a slightly duck-like flight might've grown increasingly wary in the last century or so...
In fact, there would've been genetic selection for that factor...
Finally, the IBWO's resemblance to a PIWO is far more than simply superficial (even though that's all it ultimately is). I've stared at videos and pictures until my eyes blurred, and I think I would know the difference nowadays, but then I think back to that last flicker I saw, and there's no way I could determine whether it was a red-shafted or yellow-shafted...
The number of claimed IBWO sightings that are dismissed as PWO's is illustrative of how problematic that one is . . .
Probably no new ideas in what I've put forth, but I believe they're worth repeating . . .
These birds have to eat virtually everyday and roost somewhere... we're not merely looking directly for 'needles'; we're looking for their foraging signs, their cavities, and listening for their sounds, all of which can lead to the birds themselves. It is troubling that we can find all of the above in multiple locales and STILL not come upon the birds. We now have 4 yrs of organized followup to multiple sightings, that piggybacks on 60 yrs. of disorganized followup to plenty of other sightings, and all with the same inconclusive result. I don't think I overestimate the "effectiveness" of birders, I just think the time-frame is now such, that a single indisputable photo from somewhere could have by now been expected (indeed far less conspicuous species have been re-discovered within such time-frames).
Well I've addressed these points, multiple times, with estimated numbers and rough calculations, so I won't bother again. If you want to talk yourself out of this, knock yourself out, it's your blog. But the actual statistics aren't with you. The human mind is horrible at comprehending and intuitively grasping very small or very large numbers, such as unlikely events or the areas of subcontinents. That's why we invented arithmetic and probability theories and such, so that we're not stuck with what we "think" based on our gut feelings about these things.
It seems to me that your basic premise is that there are too few sightings to permit the birds to be as mobile as some of us suggest. Such a sighting would usually consist of a brief look at a fast-flying bird. How many such encounters have occurred, and how positive does the identification have to be before we call it a sighting? I know of at least 2 recent instances in which very experienced birders have seen ivory-bills and refused to give their names publicly. One very prominent ornithologist has privately stated that if he saw an ivory-bill he would tell no one. And how many sighting reports have disappeared into the black hole at Cornell?
I do not see a particular problem with the number of sightings per se. The failure to “capture” roosting birds is another matter. Particularly in the Choctawhatchee, there are an awful lot of putative DK’s close to sunrise and sunset. This would suggest an active roost in the general area. Why weren’t the birds ever observed at a cavity there? I do see this as disturbing. It can be rationalized, but it is nevertheless a problem. I simply have a much bigger problem with accepting that highly experienced observers such as Tyler Hicks, Bob Anderson, and many others are either lying or mistaken. And extending this to all of the recent sighting reports across the range, it strains credulity far beyond the breaking point.
I found the statement below by Pulliam (pasted below from an earlier thread) to expose a surprising level of naivete.
Anyone who has tried to find bird nests rather than birds knows that there is really no comparison between the two. Birds typically minimize access to and/or visibility of nests even when adults are highly conspicuous. Marbled Murrelets are placing their nests on old-growth limbs and are nocturnal when accessing nests to reduce nest predation. The adults themselves are very visible in adjacent areas and even very vocal near the nest sites.
The analogy Pulliam draws fails at so many levels I have had to rethink my acceptance of his past views on the search and detections.
The first Marbled Murrelet nest was not located until 1974. When it was finally discovered it was found in a well-known State Park in one of North America's most heavily-birded Counties (Santa Cruz, CA), about 25 miles from downtown San Jose and 45 miles from downtown San Francisco, smack in the middle of one of the largest concentrations of birders anywhere in the Western Hemisphere. And, it wasn't even found by a birder. At that time the species was still locally common, though it had been in decline for decades.
And yet we're supposed to believe that we certainly should have found an almost extinct bird lurking in a vast area of one of North America's least birded environments in just a few years?
Sorry to have disappointed an anonymous commenter (yeah right). All analogies are inexact; I might point out that for most of the 20th Century Marbled Murrelets were rather common in the area and had been so for many decades of heavy coverage by birders and ornithologists. No one has claimed that Ivorybills have been anything more than extremely rare, anywhere, for the last 70 years. So we have a more conspicuous nest for a drastically less numerous species in a habitat that rank-and-file birders almost never enter; as compared to an internationally famous State Park in one of the U.S.'s largest, most affluent, and best educated metro areas . As I said, all analogies are inexact.
I seriously doubt that you actually accepted my views in the past.
Bill, my point is that you mention the long search for a Marbled Murrelet NEST as if it was similar to looking for an INDIVIDUAL IBWO. Unlike individual birds, nests do not fly and forage while breeding, vocalize to communicate with conspecifics, disperse or migrate to nearby or distant areas after breeding, etc. There is clearly a wide range of detectability for birds but to draw a parallel with a nest one has to conjure a species that does what a Marbled Murrelet nest does, i.e. for the entire year and in all life stages remain stationary and silent while living on moss-covered branches in the canopy of old-growth forests. An avian species like that would indeed be very hard to find and given those traits could still be undiscovered.
As to the location issue - if anything I would think that something in nature close to an affluent and wealthy area (as you characterize MAMU nesting habitat) might more easily escape detection than something in a less urban or suburban setting. The office time it takes to gain all that "wealth" means people in cities are less prone to hunt or forage as part of their daily struggle to stay alive. This is actually demonstrated by the MAMU nest discovery, which occurred when someone was harvesting wood and not when a birder was trying to build up a life list.
Actually, let's follow up on this apples and oranges comparison. Let's say, just for the sake of argument, that the murrelet nest is 100 times harder to find than the woodpecker nest. Currently the world population of Marbled Murrelets is estimated at roughly a half million birds; it was higher through the 20th Century. Let's peg the Ivorybill population at 10. So the Ivorybill nest is 100 times easier to find, but the bird is 50,000 times rarer. Hence, you'd expect to find 500 times as many Marbled Murrelet nests as Ivorybill nests. Or, if you look only at the 15,000 or so murrelets that are located in the Lower 48, you still get 15 times as many murrelet nests as Ivorybill nests... and of course that's only AFTER you figure out where to look.
Ummm... you are arguing that affluent, educated Californians are LESS likely to be out birding and looking for non-game critters (and telling scientists if they find one) than poor, rural, government-hating Southerners? And you thought *my* argument was weak and naive? The fact that birders and ornithologists didn't find the murrelet nest on their own only strengthens the analogy, rather than weakening it. Birdwatchers and ornithologists didn't find the Singer Tract Ivorybills either; they had already declared the species extinct.
The only point of the original analogy was that birders in fact have an excellent track record of missing major things, even in heavily birded areas, just by virtue of birders' being mere individual humans with our inherent perceptual abilities and limitations and being incomprehensibly outnumbered by birds and trees. I think plenty of knowledgeable people would have argued in 1973 that if Marbled Murrelets were nesting in Big Basin someone would have noticed by now. If you want to tease the comparison apart thread by thread go right ahead, but the overall fact that birders find far less of what is out there than we often think we do stands.
But lots of Ivorybills HAVE been found. There have been numerous sightings in recent years, notably by Mike Collins and Geoff Hill's team. These birds DID stay in an area for a reasonable amount of time. Geoff Hill is returning to try to document them again. So they are there, they are not wandering aimlessly and never returning to old ground, because people are repeatedly recording them in the same general areas.
I'm sure Geoff Hill will get a high quality film or photograph of one of those multiple pairs down there. I mean, they must still be around there, right?
So, do they wander? or are they faithful to certain hotspots as some would have us believe? If it's the latter case, then documentation is surely just a matter of time.
Bill you are changing your position to make your points. Your original MAMU/IBWO comparison said this after you talked about the discovery of a MAMU nest:
And yet we're supposed to believe that we certainly should have found an almost extinct bird lurking in a vast area of one of North America's least birded environments in just a few years?
So you clearly were comparing the detectability of a MAMU nest with finding "an almost extinct bird" and that was the reason for my questioning your judgment. Given that your original comparison was between a MAMU nest and an individual IBWO. your 5:26 post above really doesn't relate to any earlier comments or discussion.
My point about how perceptive an urban vs. rural population is likely to be about the plants and animals around them relates to the fact that subsistence hunting, fishing and foraging is more common in rural populations - and certainly common in impoverished rural areas both in this country and worldwide. Ignoring your attempts to pass judgment on people outside of your social circle ("poor, rural, government-hating Southerners"), I think it is clear that people who still get some or most of their food from "the land" are more aware of what is going on in the nearby natural areas than someone who drives by those area on their way to their cubicle - or heading off to an exotic birding location. That is, someone who realizes their knowledge of a natural area will help feed their family is more aware of the species they encounter than someone who is looking to tick off something for their "state list".
My you presume a lot. Outside my social circle? I live in one of Tennessee's poorest and most rural counties. Most of my neighbors did not finish high school, only about half have regular "jobs."
Few of my friends here attended college. Many are on public assistance. Most hunt. And yes, almost all hate the government. They consider the state wildlife agency their enemy. I have lived in the South most of my life, much of it in small towns, and could claim membership in the Sons of the Confederacy if I were so inclined. I wear camo to Tractor Supply and drive an old ford truck. I have a Chevy up on blocks in the front yard, on which chickens regularly roost. Don't YOU lecture ME about rural Southerners. What causes you to think you know anything about me or my social circles? Actually, don't bother answering that, my participation is this dialog is ended. All you are doing now is engaging in tedious legalistic parsing of what was provided just as a simple example of how inefficient birders can be at locating rare or difficult things.
Bill, thanks for admitting you misspoke with the MAMU/IBWO comparison. That was my only issue of concern and one I felt I should address.
My comments on your comparisons of the demographics of California ("affluent and educated") vs. the rural poor assumed you were denigrating the latter - or at least their ability to be aware of their surroundings. Sorry if you had no such intention.
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