Sangahyando
Well-known member
Goldeneyes nest in tree cavities. Maybe they don't breed in your region, but they are certainly seen around forests in some areas.
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Ivory-Billed Woodpecker continued (2 Viewers)
- Thread starter motiheal
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Thanks, strikes me as unlikely though, especially as the drug cartels formed in the 1980s and the species went extinct around 1956. I'm pasting the relevant section from BOTW as it is useful in the context of IBWO too, below. Note that the species remained easy to detect despite enduring hunting pressure that was likely heavier than that directed towards IBWO. [edit saw jenks86 post after writing this - also useful background on decline drivers].
Conservation Status
Probably extinct. No confirmed reports since 1956, when it was filmed in the state of Durango (34). There are a number of claimed but undocumented sightings, including several post-1965 reports, primarily from the northern portion of the range in Sonora, Chihuahua, and Durango (see discussion in 36, 5). All original threats, including widespread subsistence hunting, logging, and forest clearance for agriculture are still present throughout the range. Behavioral characteristics, including being highly vocal, habitually returning to the same foraging and nesting sites, and traveling in pairs and groups made it an easy target, and make the chances of undetected surviving individuals remote (5). Various targeted search efforts since mid-1990s have failed to find any individuals. Centuries of hunting, for food and sport, and because parts of this bird were thought to have useful medicinal properties, followed by the degradation and destruction of the habitat, have ensured that the species’ dwindling numbers continued to fall to unsustainable levels. No reserve ever had been established with the aim of protecting this unique woodpecker, and it is now too late.Effects of Human Activity
Tanner (29) stated that "while at first I believed that logging of the pine forest was the primary cause of the disappearance of the Imperial Woodpecker, my observations in Durango have convinced me that shooting by man is the chief cause of its elimination". Tanner also listed a number of other causes for persecution, including that the young were a delicacy sought after by native inhabitants; that the plumage was thought to have health benefits; that the feathers were particularly valuable; that the feathers, when burned, produced fumes that had medicinal properties; and also that the bill had medicinal properties. After detailing a number of historical accounts of shooting, he related a more recent report that "in southern Durango, around a new lumbering operation, the inhabitants claimed in 1953 to have shot 12 of the big woodpeckers within about a year".All accounts describe Imperials as not only being large and conspicuous, but noisy, and habitually found during the fall and winter in groups of from 2 to up to 10. Early naturalists such as E. W. Nelson observed that these birds were "surprisingly easy to stalk, even after being hunted and shot at for several days". Nor did pitoreáles tend to fly away when one was fired upon, as "they showed considerable attachment to one another and when one was shot the other members of the flock remained scattered about on the trees for a short time calling each other at intervals…"
Lumholtz (27: 212) offered an explanation for the birds increasing scarcity "The giant woodpecker is seen in the more remote parts, but it is on the point of being exterminated, because the Tarahumares consider his one or two young such a delicacy that they do not hesitate to cut down even large trees to get at their nests. The Mexicans shoot them because their plumage is thought to be beneficial to health. It is held close to the ears and the head in order to impart its supposed magnetism and keep out the maleficent effects of the wind. In the pairing season these birds keep up a chattering noise, which to my ears was far from disagreeable, but very irritating to a Mexican whom I employed. He used to shoot the birds because they annoyed him".
Lammertink et al. (36) interviewed local inhabitants within the range of the Imperial Woodpecker, and found that the most frequent reason stated for shooting the birds was that they were large targets that people would shoot for fun or to get a closer look. Secondly they were hunted for medicinal purposes, as the feathers of the head and the bill were said to have value in curing various ailments. The third most frequent stated reason was hunting for food. Plimpton (39) relates a story of a local inhabitant in Chihuahua who claimed that an Imperial Woodpecker was "a great piece of meat". He also relates that locals killed the woodpeckers to put their feathers in their hats.
Imperial Woodpeckers also were eagerly sought by early collectors, including Wilmot W. Brown (40). In 1905 in the Mormon colonies of western Chihuahua he took 17 specimens in two weeks. He had apparently spoken of the value of the birds to well-heeled American collectors. Paying top dollar for specimens naturally led to excesses as illustrated by (41):
“Recently there came to my knowledge facts relative to a deplorable slaughter of the Imperial Woodpecker (Campephilus imperialis), not so very far south of our border. Two prospectors (one of whom imparted the information given herewith) were working over a region in west central Chihuahua some fifty miles west of Terrazas (pueblo), a mountainous and heavily forested country, much frequented by the bird in subject. One of the men had heard somewhere of the rarity of the species, and that it bore a commercial value, but erroneously, his conception was that the bill was the portion in demand, and not the prepared skin. Working on this idea he shot some seventeen of the magnificent creatures in the course of a few months, and cut off the bills, figuring them at $25.00 each, until on reaching civilization again, he was chagrined to find his material utterly worthless.”
L. A. Carlton (42), who kept a diary of his hunting trip into the sierra, revealed how high the price had risen: "Saw giant woodpecker today. Rare bird and to be found only in these mountains. His coloring is gorgeous—blue-black, white and red. Very large. Perhaps twenty-four inches in length. The Whettens [J. A. Whetten was the party’s Mormon guide] tell us that some museum or ornithologist recently procured a specimen here by paying $1500.00 for its capture".
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Allen & Kellogg (1937) is a fantastic account - link
"Contrary to most published accounts, however, the birds were not particularly wary and soon became so accustomed to our presence that they would enter the nest-hole with one of us standing at the base of the tree and later even when one of us was descending from a blind which we built on April 9 in the top of an adjacent rock elm, twenty feet distant from the nest."
The paper describes monitoring at nests in Louisiana and Florida, at no point do we get the impression that we are dealing with birds that are difficult to study and document, even with archaic technology.
If anybody wants to see an Ivory-billed Woodpecker there is company that does guided trips.
nationalbiodiversityparks.org
Ivory-billed Woodpecker Trips - National Biodiversity Parks
nationalbiodiversityparks.org
bottomlands
Well-known member
If anybody wants to see an Ivory-billed Woodpecker there is company that does guided trips.
Ivory-billed Woodpecker Trips - National Biodiversity Parks
Yes, note the last name on this list of staff:
National Biodiversity Parks, Inc.
www.angelfire.com
If anybody wants to see an Ivory-billed Woodpecker there is company that does guided trips.
Ivory-billed Woodpecker Trips - National Biodiversity Parks
any internal consistency of the website's syntax and pseudo-scientific diatribes with posters in this thread is presumably entirely coincidental.
Thanks for clarification and apologies to MC for conflating him with 1TS in case he is following.
The Ivory Bill is not alone, the Campephilus genus is substantially represented in Latin America.
So there is plenty of scope for reintroductions of a similar bird from further south to fill the IB niche.
There should be something comparable in southern Chile or Argentina, the Magellanic is probably too far south.
Any suggestions from people who know that part of the hemisphere?
So there is plenty of scope for reintroductions of a similar bird from further south to fill the IB niche.
There should be something comparable in southern Chile or Argentina, the Magellanic is probably too far south.
Any suggestions from people who know that part of the hemisphere?
If only it were that easy, "lol". Still, I suppose it all drives site traffic, so the advertisers at least should be happy...
A few thoughts that struck me reading the last few pages:
- Regarding avoidance behaviour - having read some commentary relating to Snyder's "Alternative Hypothesis", it's easy to accept that the ivory-bill, along with other woodpeckers and indeed anything edible, was heavily hunted in that post-Civil War to say 1940s period, and that it would likely have become shyer as a consequence (although worth noting that Tanner and his guides did succeed in finding and photographing "his" birds). But over the last 50-70 years there would have been very little hunting pressure. Quite a few birds and animals once very shy (and rare) due to persecution have not only increased in numbers but also become much easier to observe after said persecution diminished - from grey whales in Baja California to wolves and bears in Europe and raptors in Europe and some parts of the UK (and no doubt there are many other examples). Back in the 1920s, Bucknill and Chasen (authors of one of the first books on the birds of Singapore) wrote of the stork-billed kingfisher: "...as one drifts along the edge of the mangrove one may see, perhaps a hundred yards ahead, a large highly coloured bird leave its post and plunge into the water causing a fair splash in so doing. When it returns to its seat in the mangrove it may be possible to push the boat closer for a nearer view but usually, on the first sign of danger, the wary bird darts off with a swift, straight flight at no great height over the water and thus it will precede the sampan for perhaps a mile or two always darting away when one is a hundred yards or so distant." (I have highlighted the last sentence bearing in mind the discussion up-thread on "flush distance".) Today the same species can be easily located and photographed. There would seem no reason for the ivory-bill not to have become gradually less elusive over the (pretty considerable) length of time since that period of intense hunting pressure?
- Regarding the wingbeat analysis - it seems to me that instead of the endless back and forth analysis of poor quality video clips of several seconds' duration, it might be better for all concerned if better footage could be filmed. Between the improvements in photo and video gear over the last 20 years or so, and that some searchers claim fairly regular sightings, one can only hope better (indeed, definitive) footage or photos will soon be taken. Which leads on to...
- In Michael Collins' article published 2019 he estimates a population "in the order of 100", and comments that "southern swamp forests have been recovering from logging for several decades". If there are indeed 100-odd birds in suitable (and improving) habitat, it would seem reasonable that their numbers will, if only gradually, increase. The question is - how long will it take before the definitive photo/video appears? And if not - how long will the "believers" wait till they accept the bird is gone?
- I'm wondering how many of the really experienced "world birders" out there - the folks that travel to places that are even more inaccessible/unpleasant than ivory-bill territory - the Amazon, West Africa, Borneo, Papua New Guinea, etc. - have seriously looked for the ivory-bill over the last 20-30 years, and with what results? Some BF members have literally thousands of species on their lists - have any of you guys considered trying to add the ivory-bill to your list, and if not, why not?
Cheers
patudo
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Welsh Peregrine
Well-known member
I suppose I would come in your “World Birder” category having a list in the thousands and having visited all four of the locations you mentioned. Why have I not sought out Ivory-bills? Too little time; there are still thousands of easier species to go after! Secondly, I am based in the UK; if I were in the US then I might try, but from this distance I have 3 or 4 areas which I haven’t visited which would bring in a guaranteed species list (Alaska, Hawaii, Colorado, Arizona...) Finally, too little reason to expect success; no World Birder has managed to “twitch” Ivory-bills; if I want to try the impossible I would be better off trying for Kakapo, Himalayan Quail or Night Parrot!
1TruthSeeker
Well-known member
HZ of the Ivory-billed; the end of the fallacy that an SD 10 wing beat HZ of Pileated can EXIST
You did not meet the basic request made to examine all the evidence. The usual parsing.
You have presented no evidence of any kind that in level flight, wing beat HZ of this fictional Pileated of yours varied anywhere close to your baseless claims. You have neglected to relate what the probability is of any Pileated on Earth having the 8.4 HZ observed in the LA flyunder bird.
Greater than 9 standard deviations means there is a 99.9999999% etc, rounded to 100% chance it is not a PIWO. Accepted scientific protocol calls this FACT or SURETY it was not a PI. No doubt this is why you would not put a percent number to the > 9 SD value given to the subject IB in the video. And why we have not and will not see any counter paper to Collin's subject abstract.
The Empirical Rule is commonly known in science and statistics. Also called the 68-96-99.7 rule. The numbers are the percentage of all observations in normally distributed natural situations within 2, 4 and 6 standard deviations respectively. In science circles if you get a measured value within 6 SD is is called near certainty. At 9 plus SD the subject video is 100% surely not a PI unequivocally considering all here and the LA paper.
Collins videoed a large woodpecker with white on the dorsal trailing half of wing perfect for IB some white on top of back perfect for IB, wing binding unlike PI, flight speed never seen for PI, wings longer and smaller relative cord that PI, and more. Hausken thinks you look at only HZ, fail to look for easily found PI videos to help his assertions (suspecting it was impossible to find one, disincentivized him ), fails to do any research, and then calls the bird an unusually fast PI. That is not true skepticism, its such poor work, I fail to even elevate it to a good attempt at pseudoscience. Rather it's an attempt to insult all involved.
Amazingly he thinks no one knows that the literature, from Audubon to Zickefoose, is replete with references to the rapid pintail-like flight of the IB vs the lumbering flight, crow-like of the Pileated. Flight style differences of the 2 species is in the literature many times for over 150 years.
Of course you used a bit of jargon to distract us from your slight of hand. You said: "To draw a numeric conclusion from the size of the standard deviation, you must know, or be able to assume with a high degree of confidence, that the observed values follow the normal (Gaussian) distribution ... which can usually be safely assumed if the results vary stochastically due to the influence of a sufficiently high number of small random influences."
Anyone can find or get PIWO flight data or video on Nolin's website, Pulliam's site with graphs of many birds, Cornell site, many sites. Or get outside. I have measured ~ 100 PIWO flight sequences including two in the field chased by an American crow and great crested flycatcher. I always got below 6 HZ, one being chased was 5.8 the other 5.6, one other in high 5 HZ. SD was a fraction of the total HZ like Tobalske.
"Tobalske obtained the flap rate statistics of the Pileated Woodpecker (5.2 Hz mean and 0.4 Hz standard deviation) from well-sampled data that were obtained in Montana (Tobalske 1996);"
Tobalske's SD was .4 HZ well within the Gaussian curve. Nolins birds were all well within the curve, Pulliams birds the same. Videos on all sites within.
Normally distributed measurement data sets of almost all body movements of animals fit completely under the normal distribution curve (3 standard deviations from mean). Why would a bird flying in a dangerous world, fly much slower than its maximum all the time, and why would most if it not all species fly too slowly, as governed by flight dynamics and physiology, and fall out of the sky? Flight requires a certain balance between a minimum HZ to create both lift and propulsion, and a maximum to address predation and movement needs. These pressures push the range in from the extremes HZ at either end and a variance outside a normal distribution of 3 SD does not exist for any Pileated Woodpecker. Physics exerts pressure on delicate birds, and limits top HZ range of Pileateds and all birds. Birds just can't linearly increase speed higher and higher under certain situations as if they were made of steel rather than flesh and tendons that tears, and hollow bones that can crack. An SD of 9 plus is an extraordinary claim for a PI; all very publishable for you if true. You have however not presented any evidence at all.
The wing flap HZ of bird species have a rather narrow range per all of the literature. Flap number for wings cannot be exorbitant, since the force needed to accelerate the wing at each downstroke would exceed the pectoralis muscles output capacity and would incur the risk of breaking the muscle attachment or stress fracture the humerus. Wing flap has a reasonable minimum not far from the maximum, as muscles strain rates during shortening have a narrow range, governed by fuel energy conversion to work, and to maintain flight and metabolic efficiency. A woodpecker may vary its HZ and modulate to small degree, but within a normal curve of 3 SD from the mean, for each of these: taking off, cruising horizontally, climbing or descending, but only a small range of wingbeat frequencies is available and shown for any particular individual bird, or species.
All birds show small HZ SDs. Hundreds are published.
Here is Hz followed by the small + -SDs for a few:
Diomedea exulans Wandering albatross 2 .49±0.11
Diomedea melanophris Black-browed albatross 2.97±0.15
Macronectes giganteus/M. halli Giant petrel 3.14±0.19
Procellaria aequinoctialis White-chinned petrel 3.93±0.10 − −−
Daption capensis Cape pigeon 5.61±0.55
Pachyptila desolata Dove prion 5.42±0.36
Oceanites oceanicus Wilson’s storm-petrel 7.65±0.60
Pelecanoides georgicus South Georgia diving petrel 12.3±0.64 − −−
Pelecanoides urinatrix Common diving petrel 12.3±0.64 − −−
Phalacrocorax atriceps Blue-eyed shag 5.85±0.25 − −−
Catharacta skua Southern skua 3.95±0.21 − −−
Larus dominicanus Kelp gull 3.46±0.16 − −−
Chionis alba Sheathbill 6.35±0.29 − −−
Anas georgica South Georgia pintail 7.62±0.23 − −−
Cygnus cygnus Whooper swan 3.56±0.11 − −
I know everyone is not a scientist; many may not be aware of the accepted place the skeptical point of view has vs the pseudoskeptical abuse of science does not have. Skeptics have responsibilities and standards, just like the the other side, despite what goes on here. True skepticism is important. In general it does not turn over formal decisions by tested and proven scientists accustomed and trained in evidence review, and negating peer reviewed papers takes more than creating doubt, and parsing out a small piece of evidence, mashing the literature up, and then ignoring entire data sets completely. Videos, with white in right places, audio evidence , field notes, more......, all of it must be looked at, anthing less is only pseudoscience.
This is why you can never be successful in ever overturning the papers and videos and why published skeptics have all failed with the USFWS, etc. You think you have no responsibilities as stated (see below). This a blatant perversion of science.
Additionally the annihilation of true skepticism by your repetitive pseudoskeptical (PS) methods will not work were it matters. It will enable and habituate those here, as it has; its manipulative and has no place in conservation or any bird forum.
1TruthSeeker
Well-known member
Part 2 IBWO Flight HZ -----Recently you have violated true skeptic standards and embraced published pseudoskeptical methods as follows:
These methods in red have become common place on forums and chat rooms. Attackers roam around not addressing evidence.
l
A) denying IB exists when you try to create doubt but your arguments are barely weak, not even suggestive to wrong. This is classical Pseudoskepticism.
YOU: Tobalske only examined 11 PIWOs the best that can be claimed is the video doesn't match these 11. This Is PS for several reasons. The IB community has examined hundreds of PIWOs inflight in vivo, and on tapes. Tobalske and a substantial number of studies have confirmed by direct data collection that HZ does not range much within and across species, if the action being observed is the same (e.g. level flight vs climbing flight, vs takeoffs, etc.). Multiple skeptics and pseudoskeptics have been directly asked for the video of the black swan, supercharged PI. Its not out there. A true skeptic looks at many many PIs, this easily eclipsing the number you found and reviewed N = (0).
b) double standards that every data set supporting IB is wrong but not using the same vigorous standard to your own data or you have no data, this is PS
c) the tendency to discredit rather than investigate is PS
I don't have to disprove the existence of the Ivory-Billed Woodpecker any more than I have to disprove the existence of, say, the Yeti.
d) presents insufficient evidence or no evidence is PS
Being outside 10 sigma would be an impressive probability in the proper context (no certainty, even there), but in the case of the flap rate comparison, it doesn't mean anything because a bird's flap rate is, in approximation, arbitrarily variable depending on the requirements, and thus not a random influence.
e) not reviewing all the evidence or any of it is PS
I don't have to disprove the existence of the Ivory-Billed Woodpecker any more than I have to disprove the existence of, say, the Yeti.
f) makes substantial counter claims is PS
You can only draw probabilistic conclusions from the standard deviations, so even in the best of cases, you could not rule out the Pileated Woodpecker with certainty.
g) counter claims based on plausibility rather than empirical value is PS
You can only draw probabilistic conclusions from the standard deviations, so even in the best of cases, you could not rule out the Pileated Woodpecker with certainty.
h) suggest that some unconvincing evidence is grounds for complete dismissal of the find is PS
i) often attempt to exaggerate their comments to discredit evidence rather than investigate is PS
j) when interfacing with others often gang up on them with rude and condescending remarks, PS
k) do not mind creating an internet cesspoll to drive way those that frustrate them by recognizing PS
l) make by definition impossible to know statements , such as extinction is PS
m) show a lack of knowledge of their subjects is PS
You can only draw probabilistic conclusions from the standard deviations, so even in the best of cases, you could not rule out the Pileated Woodpecker with certainty.
These methods in red have become common place on forums and chat rooms. Attackers roam around not addressing evidence.
l
A) denying IB exists when you try to create doubt but your arguments are barely weak, not even suggestive to wrong. This is classical Pseudoskepticism.
YOU: Tobalske only examined 11 PIWOs the best that can be claimed is the video doesn't match these 11. This Is PS for several reasons. The IB community has examined hundreds of PIWOs inflight in vivo, and on tapes. Tobalske and a substantial number of studies have confirmed by direct data collection that HZ does not range much within and across species, if the action being observed is the same (e.g. level flight vs climbing flight, vs takeoffs, etc.). Multiple skeptics and pseudoskeptics have been directly asked for the video of the black swan, supercharged PI. Its not out there. A true skeptic looks at many many PIs, this easily eclipsing the number you found and reviewed N = (0).
b) double standards that every data set supporting IB is wrong but not using the same vigorous standard to your own data or you have no data, this is PS
c) the tendency to discredit rather than investigate is PS
I don't have to disprove the existence of the Ivory-Billed Woodpecker any more than I have to disprove the existence of, say, the Yeti.
d) presents insufficient evidence or no evidence is PS
Being outside 10 sigma would be an impressive probability in the proper context (no certainty, even there), but in the case of the flap rate comparison, it doesn't mean anything because a bird's flap rate is, in approximation, arbitrarily variable depending on the requirements, and thus not a random influence.
e) not reviewing all the evidence or any of it is PS
I don't have to disprove the existence of the Ivory-Billed Woodpecker any more than I have to disprove the existence of, say, the Yeti.
f) makes substantial counter claims is PS
You can only draw probabilistic conclusions from the standard deviations, so even in the best of cases, you could not rule out the Pileated Woodpecker with certainty.
g) counter claims based on plausibility rather than empirical value is PS
You can only draw probabilistic conclusions from the standard deviations, so even in the best of cases, you could not rule out the Pileated Woodpecker with certainty.
h) suggest that some unconvincing evidence is grounds for complete dismissal of the find is PS
i) often attempt to exaggerate their comments to discredit evidence rather than investigate is PS
j) when interfacing with others often gang up on them with rude and condescending remarks, PS
k) do not mind creating an internet cesspoll to drive way those that frustrate them by recognizing PS
l) make by definition impossible to know statements , such as extinction is PS
m) show a lack of knowledge of their subjects is PS
You can only draw probabilistic conclusions from the standard deviations, so even in the best of cases, you could not rule out the Pileated Woodpecker with certainty.
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Welsh Peregrine
Well-known member
So I have continued to look at the evidence presented; some of the data is indeed interesting, although none of it looks conclusive to me. When I was an active researcher in Bristol in the late 1970’s I was just along the corridor from Colin Pennycuick’s research group, which also contained Jeremy Rayner, Geoffrey Spedding and Keith Scholey. The last of these is the one I suggest contacting. He is now a Natural History film producer, whose most recent credits are Attenborough’s Perfect Planet. With his contacts in the industry, he would be the ideal person to obtain clear and incontrovertible proof if it is possible to do so; I genuinely look forward to seeing such film.
Larry Sweetland
Formerly 'Larry Wheatland'
I really think that some people are overthinking this. The only equation that needs to be applied here is: big woodpecker x zero easily identifiable images in several decades = there aren't any there.
Hi Mike,
Nor do I intend to. The fallacy you committed in 2019 is quite independent of any data you present now - it's a flaw in your logics.
Nor do I intend to. I'm pointing out that your claim is based on a fallacy that means your conclusions are meaningless and your argument is void, regardless of the evidence.
Of course, you could bring evidence that shows that the underlying assumption that wing beat frequency of a bird is independent of its power requirement at any moment. That - and only that - would address my main criticism.
Please, if you take anything away from this thread: The SI symbol for Hertz is "Hz", never "HZ".
That only holds true for a Gaussian distribution specifically. One can only assume a Gaussian distribuion under specific conditions, and the most important condition is that all individual deviations are small, and random. As a bird's wing flap frequency is subject to a non-random influence, the power requirement.
(That's what my distracting jargon" paragraph said. Sorry you couldn't follow, but I used standard terminology I didn't expect someone actually applying statistics to his fieldwork results to be unfamiliar with.)
Tobalske restricted himself to observing easily observed flight situations with a fairly constant (and low) power requirement. You'd be more or less fine if you'd apply the standard deviation to birds flying at the same power level, but a bird going at high speed (or a flushed bird in the acceleration phase) violates the assumptions under which the standard deviation gives you any useful information.
I don't need to. You basically wrote, "1 + 2 = 4, so <conclusion>". I'm telling you your logic is wrong and your conclusion is unsupported.
Excellent, that's a step in the right direction. However, the numbers don't mean anything by themselves. Remember, you need to bring bring evidence that shows that your implicit assumption is valid: Wing beat frequency of a bird is independent of its power requirement at any moment.
If the numbers you quoted are for any specific flight situation, they don't help you at all.
So what are your credentials? Seriously, we are talking about high school-level math here that are central to any evaluation of statistical data ...
Regards,
Henning[/QUOTE]
Nor do I intend to. The fallacy you committed in 2019 is quite independent of any data you present now - it's a flaw in your logics.
Nor do I intend to. I'm pointing out that your claim is based on a fallacy that means your conclusions are meaningless and your argument is void, regardless of the evidence.
Of course, you could bring evidence that shows that the underlying assumption that wing beat frequency of a bird is independent of its power requirement at any moment. That - and only that - would address my main criticism.
Please, if you take anything away from this thread: The SI symbol for Hertz is "Hz", never "HZ".
That only holds true for a Gaussian distribution specifically. One can only assume a Gaussian distribuion under specific conditions, and the most important condition is that all individual deviations are small, and random. As a bird's wing flap frequency is subject to a non-random influence, the power requirement.
(That's what my distracting jargon" paragraph said. Sorry you couldn't follow, but I used standard terminology I didn't expect someone actually applying statistics to his fieldwork results to be unfamiliar with.)
Tobalske restricted himself to observing easily observed flight situations with a fairly constant (and low) power requirement. You'd be more or less fine if you'd apply the standard deviation to birds flying at the same power level, but a bird going at high speed (or a flushed bird in the acceleration phase) violates the assumptions under which the standard deviation gives you any useful information.
I don't need to. You basically wrote, "1 + 2 = 4, so <conclusion>". I'm telling you your logic is wrong and your conclusion is unsupported.
Excellent, that's a step in the right direction. However, the numbers don't mean anything by themselves. Remember, you need to bring bring evidence that shows that your implicit assumption is valid: Wing beat frequency of a bird is independent of its power requirement at any moment.
If the numbers you quoted are for any specific flight situation, they don't help you at all.
So what are your credentials? Seriously, we are talking about high school-level math here that are central to any evaluation of statistical data ...
Regards,
Henning[/QUOTE]
Welsh Peregrine
Well-known member
Also, please look at the list of species in your table from Pennycuick; a set of seabirds and a swan is not a reliable indication of Woodpecker aerodynamics! Proof that the Gaussian distribution applies is needed here.
Hi,
Thanks a lot for the link, that might explain a number of things I found puzzling so far ... for example, what motivation anyone might have to exert so much effort on depicting the Ivory-Billed Woodpecker as non-extinct on a birders' forum, and where the suggested multitude of recent sightings might stem from. (I noticed there is a link to a sighting report form for Ivory-Billed Woodpecker on that site!)
Regards,
Henning
If anybody wants to see an Ivory-billed Woodpecker there is company that does guided trips.
Ivory-billed Woodpecker Trips - National Biodiversity Parks
Thanks a lot for the link, that might explain a number of things I found puzzling so far ... for example, what motivation anyone might have to exert so much effort on depicting the Ivory-Billed Woodpecker as non-extinct on a birders' forum, and where the suggested multitude of recent sightings might stem from. (I noticed there is a link to a sighting report form for Ivory-Billed Woodpecker on that site!)
Regards,
Henning
Yourself and several others I'd imagine, I assume that text was written by the 'President' Fred Virrazzi who is an IBWO searcher with a history of posting to Birdforum about IBWO in an often combative nature and not sparing of the insults (granted there were plenty on both sides indulging).
Anyway back to the website which contains such utter unsubstantiated nonsense:
"Additionally a pair can range over 6 to 50 square miles"
So you have radio/GPS/satellite-tags on these birds?
"An Ivory-bill likely needs only an hour or two per day to meet its caloric needs, this can likely be accomplished within a few quality square miles of its range."
So in addition to the tags you have data on IBWO food intake rates, the energy contained in that food and the bird's basal metabolic rate? Are you sure you aren't making all this up?
"The last Ivory-bills avoid areas frequented by humans and gravitate to areas where hunters, hikers and birders seldom or cannot visit often because of physical barriers."
Ah yes, they gravitate to areas where only NBP members dare to boldly go!
This is my absolute favorite:
"Temporal points in the breeding phenology will however put various spatial, caloric and foraging demands on a pair of Ivory-bills. At these times Ivory-bills must expand their daily movements in response to hormone levels and perhaps photoperiod and other physical characteristics of their habitat."
Throwing together a bunch of long words that imply the sort of knowledge of the species and system that to date only researchers working with model species like scrub-jays and great tits can boast to understand might baffle and impress some elderly donors with no scientific knowledge but not everyone.
"Please join us on your own custom trip by filling out the form below; up to 50% of trip costs may be tax deductible."
Sounds like a great offer? What are my chances of seeing an IBWO on these trips. Well:
"It takes field experience, skill, patience and substantial effort to find one bird; it’s more like a hunting expedition than the usual birding outing. Regardless on multiple occasions we have located a bird within one field week in a very few select areas."
Wow, I only need a week to see one! Just like Tanner et al. Amazing! If I was an elderly person I would love to spend my money and my dotage on seeing an IBWO. Take my money!
To summarize:
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Mark Lew1s
My real name is Mark Lewis
Pseudoscience to one side for a moment. What on earth is to be gained from coming here and convincing a largely European audience who are here in a non-professional capacity that these birds still exist? If there are IBWO out there, they gain absolutely nothing at all from the (extremely) unlikely outcome that you've changed someone's mind on Birdforum.
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