In the ongoing quest to explain why we can't photograph an Ivory-bill, here's
another speculation, based on a sample size of exactly zero confirmed birds:
...it is also possible that Tim Barksdale is right, and that these birds today have home ranges measured not in tens or hundreds of square miles, but thousands!
Contrast the above with what Allen and Kellogg
published in The Auk in 1937, based on years of real Ivory-bill data from multiple states:
...the birds are non-migratory and moreover they are probably sedentary. It is our belief that most individuals spend their entire lives within a few miles of the place where they are hatched and develop little Ivorybill communities.
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14 comments:
Biological...that would take a large energy requirement for a large woodpecker that does not soar like a hawk of eagle. A bald eagle can have a homing range 30 to 40 miles along river valleys. Let's see, assuming a river valley is quasi-linear, let's assume it is 40 miles by 20 miles or so...that yields about 800 to maybe as much as 1000 square miles.
So a woodpecker that does not soar and is much smaller and presumably less mobile can cover such huge distances like an eagle and have enough energy left to survive and breed. Wow. Impressive. Of course, Arthur Allen and David Tanner were probably wrong because they only studied a small isolated population. They were different than the "real" IB woodpeckers that live today.
Furthermore if they did travel such large distances wouldn't they have a better chance of being seen? Oh.... I forgot these birds are so wary that they probably can smell humans and purposely avoid any area where a human can see them. They are especially adept at not letting any person get close enough for a good photo or video. They are smarter than us. I too believe a new specie has evolved....like Don Hendershot says..."Campephilus willowispis"
one that is smarter and wiser and likely will never be seen...except by a few chosen people with the right equipment, psyche and credentials. Even so, the field marks will always be presented as blurry. That is part of this "evolved" IB's new life history. [Paraphrased from Don Hendershot's commentary on this blog... See Wednesday, December 28, 2005 1217 pm]
Any speculation that favors the IB existence seems to be easily accepted. Any logical reasoning that points toward the IB not existing is met with hosility.
Nice open minded people in this debate! It is disgraceful how I have even seen some believers tear apart Dr Tanner's work because it does not support their false hopes of this bird being alive today. shameful.
It is very difficult to draw inferences about the expected behavior of a single individual from data collected in denser populations and breeding pairs. Any individual bird of any species can occur in virtually any habitat, and exhibit virtually any behavior. I (and many other observers) once observed and thoroughly documented a great cormorant in a Georgia cypress swamp 100 miles inland; one of very few records of the species for anywhere in the State. If you looked in the literature I suspect you woud find very few (probably zero) other accounts of that species occuring in that habitat, and the first unconfirmed report was met with serious doubt. Nonetheless, there it was. There is a long-standing addage amongst those who study animal behavior as a profession:
Under carefully defined and controlled conditions, animals will behave as they darn well please.
These probabilistic arguments about what habitat the bird should be in or how it should behave or how difficult it should be to find and photograph are examples of one of the standard fallacies of statistical analysis: attemting to make inferences about an individual based on group means. To my mind they carry even less weight than an uncorroborated single-observer sighting. Such behaviors as habitat choice and wariness are not firm, relatively invariant species characteristics as are vocalizations, size, plumage, etc.
As argued at this link , I think searchers over the last 60+ years of fruitless searching were looking for a population of at least 20-30 birds, rather than seeking a single postulated wide-ranging ghost bird.
I think it's very unlikely that such a population would behave much differently than Ivory-bills of the past.
Ideas about population sizes and dynamics at this point remain pure speculation, no less than they were two years ago. based simply on Cornell's own analysis of the data, there is robust evidence for the existence of only one male IBWO in the entire White River - Cache River area. Many would rephrase that as "at most one." The only evidences that hint at more than one bird are the double raps (ARU and observer reported) and the tree scaling. Both of these are considered by most people to be suggestive and intriguing at best; even by people who accept the visual, "kent," and video data as valid. Thus, we are discussing only the possible existence of a single lone male at this point.
This possible bird could be a member of a larger breeding population. He could be a stray from a breeding population somewhere else. He could be a lone surviving individual. There is no basis yet for knowing. There is also relatively little known of the IBWO from the days when it did have large viable populations, only a few studies under a few circumstances and many anecdotal accounts. No matter what the circumstances prove to be, by definition this bird (if it exists) is an exceptional individual under exceptional conditions.
...one of the standard fallacies of statistical analysis: attemting to make inferences about an individual based on group means.
Wouldn't it be an even greater fallacy to make inferences about a group (a population of Ivory-bills that may or may not have been living for the last 60 years) based on what may or may not be sightings of a single bird?
Tom Henderson was being humorous. And the only hostile tone in this series of comments is in the first one. There are plenty of open minded people in this debate, and the very fact that some have seen fit to divide it into camps of "skeptics and believers" is perhaps the biggest problem. This is not religion. It's field biology. And please don't blame the "other side" for creating this schism; I have seen plenty of this two-party sort of argument from all directions. The large majority are simply evaluating the evidence quietly for themselves and accepting that others may see it differently, and hoping for something more definitive.
ANYONE who puts themselves and their ideas forward publically will find themselves the target of hostile and impolite attacks. This is happening to Tom, it is happening to Gene Sparling. It is certainly happening to the Nature Conservancy and the CLO with implications that this is all just a quasi-fraudulent money grab on their part. Rudeness given does not justify rudeness in return.
I guess you meant Tim Barksdale? If so, why do you think he was being humorous? He has speculated that the parents of Elvis may have come from Florida.
Oops Don Henderson, quoted above and referenced earleir about "Campephilus wilowispus" an Arkansas outdoor writer with tongue firmly in cheek
The remark from an above comment...
"the very fact that some have seen fit to divide it into camps of "skeptics and believers" is perhaps the biggest problem"
Why is this a problem? Some believe and others don't. Black and white. If you have any small doubts then you are skeptical by definition.
By far, some believers have been very hostile to those who don't believe with ad hominem attacks (see the bird forum net thread "On the debate on the IB existence" for example) This distracts people from the real issues about the science of the matter and is truly rude.
Anyway, this is my take on this wdebate which is kind of a "truce" (at least in my mind)...
There are two camps. There are. Sorry. The believers and skeptics.
The believers need much less definitive evidence to believe.
They trust in other birder's skills, especially ones they know.
Fine. I can buy that. Personal choice. That is fine.
The skeptics are holding out for more firm evidence and until then will remain skeptical. The evidence that has been presented to date(1-3-06)...is flimsy in skeptic's opinion. many of us are in science or engineering fields and this kind of evidence would be scoffed at (at least in my field)! Sorry. So naturally we are looking for the solid evidence... Photo or video. Especially since a remnant population undetected for 60 years is so exceedingly unlikely. Defies all odds.
Maybe Hendershot was trying to be humorous...I saw that. So was I, in my first comment on this site.
Sorry if I offended anyone.
"Black and white"
Therein lies the problem, in a world that consists mostly of shades of gray.
It also means that it will never be possible to be a "believer" in the Ivorybill's extinction, because the absence of the bird on a global scale is not provable to a 100% certainty.
As a lifelong scientist I know that there are few absolute certainties, especially in the life sciences. I also know that division into us/them camps is almost always a BAD thing for scientific progress and understanding, and that the blame for this division can nearly always be placed in both "camps."
But it seems we will just have to disgaree on this, too.
On Hendershot, yes, he was being humorous, but "Many a truth is said in jest." (I believe I can take credit for being the first to quote Shakespeare on this blog.)
I do think the debate is basically divided between people who believe it has been proven beyond a reasonable doubt, and those that are skeptical that the evidence to date constitutes "proof".
I believe this blog serves a very useful purpose. Right or wrong, there are a lot of people out there pitching their belief that the bird is alive and well. I think it's appropriate to have outspoken skeptics.
I also agree that there is a lot of gray in this debate, and in science in general.
I think this has been a good exchange. Intelligent people can debate without it becoming personal. Everyone should be open to new evidence and new arguments, regardless of which "side" they or the evidence support(s).
I agree with the most recent comment. I would be more than open minded if new compelling evidence emerged. There has been nothing new since the announcement. At least none that has been "released" to the public.
I see it this way....I would believe if a credible observer like a Dr. Fitzpatrick, Dr. Jackson or another well-known ornithologist had a goodlook at this bird and not a fleeting glimpse...(see latest post on this blog). So far, fleeting glimpses is all that we have heard about by the reputable observers.
Of course, the million dollar photo or video would be a slam dunk for 99.9 percent of us. There will always be the .1 percent who would claim a hoax.
Let's hope they find something more....
Could the anonymous person that mentions a Great Cormorant in Georgia please email steve_holzman AT yahoo.com? I can't find any record of this in our Annotated Checklist (except for an Albany sighting - which is further than 100 miles from the coast). Thanks,
Steve
That's the one. Albany is only about 100 miles (maybe 130) from the *Gulf* Coast.
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