• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia

new paper on the Ivory-billed Woodpecker (1 Viewer)

Status
Not open for further replies.

fishcrow

Well-known member
Not nearly as many as you are missing, though... such as even a shred of credible evidence.

Credibility is in the eye of the beholder. Signs that my data have credibility include the published assessments of independent experts, comments made privately by other ornithologists and scientists who have studied the data, comments by anonymous reviewers, and the fact that it has been published and analyzed in a series of papers.
 

fishcrow

Well-known member
After having two of the links I tried to follow knocked back because whatever format they are in is not supported by my laptop, I gave up. I understand your desire to prove your sightings to a wider audience - do YOU understand why others are having trouble getting past the DREADFUL pictures presented?

You state that you weren't able to view the data and gave up. If that is true, how can you make any informed comment about the data, one way or the other? Just for your information, the data that you refer to as "dreadful" received strong positive assessments from independent experts. If you are expected a pretty picture, nobody has managed to obtain one since the 1930s. If you are interested in the strongest evidence for the persistence of the Ivory-billed Woodpecker that has been obtained during the past several decades, you might consider the following comments by an anonymous reviewer:

"Flight characteristics are the key to the analysis, although other aspects of wing shape and markings are also pointed out. Looking at the putative video before seeing the analysis, one may wonder how any progress on deciding if the video is of the Ivory-billed woodpecker can be made, since it is fleeting footage from far away. I am impressed by the author’s being able to provide an analysis of flap rate and takeoff and landing characteristics that is very compelling."
 

Farnboro John

Well-known member
Tobalske concluded that the bird in the video is a large woodpecker. It is a trivial matter to estimate the flap rate from the video, and the value is about ten standard deviations greater than the mean flap rate of the Pileated Woodpecker. Tobalske pointed this out with the comment, "The bird appears to have a wingbeat frequency of 10-12 Hz, which is approximately double that of the Pileated Woodpecker. So the wingbeat frequency would seem much too high (well outside three standard deviations) to be from a Pileated Woodpecker." It would be easy for anyone to step through the video one frame at a time, count the number of frames per flap cycle, estimate the flap rate, and then compare with Tobalske's results. You seem to be making an assumption that "his silence" was based on disagreement. On what point?

It is straightforward in the field to decide whether a bird is in cruising flight, taking off, escaping from danger, etc. This has been done in various studies of avian flap rate, including the ones by Pennycuick and Tobalske that are cited. To obtain the statistics of avian flap rate, the mean and standard deviation are constant values that are obtained by averaging over many events involving birds that may be flying over a range speeds that also have a statistical distribution (although this topic has apparently not been addressed in as much depth as flap rate, which is much easier to measure in the field). It is true that the flight speed of the bird in the 2008 video is very different from the range of flight speeds that Tobalske measured for the Pileated Woodpecker, but that has no bearing on the conclusion that this species may be ruled out on the basis of flap rate.

The trouble with all this misuse and abuse of statistics is that whatever the mean and standard deviations of cruise flapping of two woodpecker species (and I haven't yet seen any explanation of the supposed dataset for IBWO given the bird's existence is what is being investigated: the recent alleged data can't be used in circular justification of itself), all that is needed is the minimum and maximum for each species. If there is overlap of the two species' flap rates its game over.

I don't have a complete set either, but I already know that Pileated Woodpecker has been measured flapping at up to at least 8.6 Hz, so Tobalske's claims that 10-12 Hz is double Pileated Woodpecker's flap rate are invalid and no pratting about with dodgy statistical calculations will change that. All we know is that the minimum difference is 1.4 Hz and the maximum, 3.4 - and that is not from a measurement claimed to be Pileated Woodpecker's maximum flap rate, so there's no reason to believe Pileated can't flap faster. Indeed, as the slightly smaller bird one would expect it to be able to flap faster than the larger! One also has to wonder where on earth figures of 10-12 Hz for IBWO come from, unless its a ludicrous extrapolation from some old film.

John
 
Last edited:

Hauksen

Forum member
Hi Mike,

Tobalske concluded that the bird in the video is a large woodpecker. It is a trivial matter to estimate the flap rate from the video, and the value is about ten standard deviations greater than the mean flap rate of the Pileated Woodpecker.

It's just as elementary that the standard deviation is just an indication that the deviation from the mean is unlikely to be the results of mere random fluctuations.

The observed bird being of a different species would be one example for a systematic difference, the observed bird being a Pileated Woodpecker in a hurry is another.

Your paper doesn't even try to exclude the latter case.

It is true that the flight speed of the bird in the 2008 video is very different from the range of flight speeds that Tobalske measured for the Pileated Woodpecker, but that has no bearing on the conclusion that this species may be ruled out on the basis of flap rate.

You're basically asserting that flap rate is independend of flight speed.

If you have evidence for that, it would really boost the strength of your argument if you'd provide it.

It's not in the referenced Tobalske article, as far as I can see.

You seem to be making an assumption that "his silence" was based on disagreement. On what point?

Maybe it helps if I highlight the point:

What I actually said was, "I can't imagine he would have missed the opportunity to point out that the Pileated Woodpecker could be ruled out based on the recorded flap rate."

To put it bluntly, I believe that if Tobalske had agreed with your application of his data, he'd have said so, and I take his silence on the critical point as disagreement.

Regards,

Henning
 

amears

Well-known member
Would be nice to get this before you disappear off on your travels: Which video clearly shows the correct white wing markings for IBW?
 

Britseye

Well-known member
You state that you weren't able to view the data and gave up. If that is true, how can you make any informed comment about the data, one way or the other? Just for your information, the data that you refer to as "dreadful" received strong positive assessments from independent experts. "

I saw a number of photos of leaves and branches and some arrows pointing at something I couldn't see, as well as a couple of miscellaneous shapes that may or may not have been birds. I really hoped from the intro you gave it, that there would be something tangible there that would help maintain my interest in a subject I have only a very very small stake in. But there wasn't. I've rarely had my computer not be able to open a down-loaded video in twenty year's experience - it might be something you want to look at if you hope to draw a wider audience? The photographs, and the comments from people I know and trust, suggested I wouldn't be rewarded by trying to find the appropriate program to open them. That is why, in the spirit of helpfulness, I pointed out the shortcomings of the 'evidence' presented.

'Independent expert?' What's one of them when it's at home? Someone recently referred to my good self as a 'World Class Birder'. What does that even mean :eek!: I'm sorry... there are plenty of 'independent experts' on here who'll tell you you're photos are dreadful. 'We' are your peers, as much as anyone. We've been there, done that, talked the talk and walked the walk. Again, despite your disingenuous and defensive reply to my attempt to reach out to you with compassion, I'l tell you the truth: I don't disbelieve your story at all. But I understand why others would.
 

fishcrow

Well-known member
It's just as elementary that the standard deviation is just an indication that the deviation from the mean is unlikely to be the results of mere random fluctuations.
The standard deviation is a measure of how observations fluctuate about the mean. In this case, the flap rate of the bird in the video is about ten standard deviations greater than the mean flap rate of the Pileated Woodpecker. That species may therefore be ruled out. I consulted with experts in applications of statistics about what may be concluded from ten standard deviations. They are in agreement that ten standard deviations is conclusive. According to David Banks of Duke University, for example, it is a statistical "slam dunk" that the bird in the video is not a Pileated Woodpecker.
 

DMW

Well-known member
The irony here is that all of us would love for fishcrow to be right. We all want there to be a population of IBWOs somewhere, and would be delighted to see anything that was remotely suggestive of the species, let alone conclusive. A few years ago, another long-lost species was sort of rediscovered on Bird Forum, when somebody posted some photos of a pigeon from Indonesia, and asked for comments. The photos were terrible, but there was just enough detail for a strong case for the bird being Silvery Pigeon to be made. This was subsequently demonstrated to be correct.

Sadly the current thread is basically the opposite. We are being told that half a dozen pixels are, through the magic of peer-reviewed science, conclusive proof and we are more or less idiots if we disagree.
 

amears

Well-known member
They are discussed starting at about 5:38 in this lecture on the 2008 video.

Thanks again and well done for continuing the debate in the face of adversity.

Wings look dark in some frames and pale in others, which is not in the least bit unusual for a host of species, and I couldn’t possibly discern more detail than that with footage of such desperately poor quality. For what it’s worth, my money would be on a Belted K.

If I ever come face to face with an IBW, I will not be concentrating on eye colour. And I don’t plan to send the British Birds Rarities Committee a cartoon of me not seeing a bird as evidence of the next rarity I find (if indeed there ever is another one!). I do appreciate the cartoons are only illustrative, they just seem really odd in a scientific paper - and they seem to do more harm than good.

I tend to agree with all the negative points made so far on here I’m afraid.

Really hope we’re all wrong and they are out there. Possibly at odds with others, it wouldn’t even need a photo for me, just a convincing description that rang true and had all the hall marks of an experienced and authentic birder, preferably one with a decent reputation (and I know nothing of yours I’m afraid so I remain neutral there).
 

Hauksen

Forum member
Hi Mike,

The standard deviation is a measure of how observations fluctuate about the mean. In this case, the flap rate of the bird in the video is about ten standard deviations greater than the mean flap rate of the Pileated Woodpecker. That species may therefore be ruled out.

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.

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.

That assumption goes out of the window the moment a systematic influence, such as the bird reacting to the power requirement for high-speed flight, enters the picture.

Regards,

Henning
 

fishcrow

Well-known member
I saw a number of photos of leaves and branches and some arrows pointing at something I couldn't see, as well as a couple of miscellaneous shapes that may or may not have been birds. I really hoped from the intro you gave it, that there would be something tangible there that would help maintain my interest in a subject I have only a very very small stake in. But there wasn't. I've rarely had my computer not be able to open a down-loaded video in twenty year's experience - it might be something you want to look at if you hope to draw a wider audience? The photographs, and the comments from people I know and trust, suggested I wouldn't be rewarded by trying to find the appropriate program to open them. That is why, in the spirit of helpfulness, I pointed out the shortcomings of the 'evidence' presented.

'Independent expert?' What's one of them when it's at home? Someone recently referred to my good self as a 'World Class Birder'. What does that even mean :eek!: I'm sorry... there are plenty of 'independent experts' on here who'll tell you you're photos are dreadful. 'We' are your peers, as much as anyone. We've been there, done that, talked the talk and walked the walk. Again, despite your disingenuous and defensive reply to my attempt to reach out to you with compassion, I'l tell you the truth: I don't disbelieve your story at all. But I understand why others would.
I'm sorry that you aren't able to play the mp4 and mov files (which are industry standards) on your computer. Which specific videos gave you trouble? I have always used standard programs to encode videos. The ones that I have posted on YouTube have been viewed for a total of 254 days of watch time. It seems puzzling that you would comment on evidence that you haven't even seen. After carefully studying the data, ornithologists and other scientists have made very positive comments (including that the videos are convincing) about the evidence and recommended it for publication.

The independent experts whose comments on the videos appear in my papers include Bret Tobalske, who is widely regarded as THE expert on woodpecker flight mechanics, and Julie Zickefoose, an avian artist whose paintings of the Ivory-billed Woodpecker have appeared on the covers of major publications in ornithology. You seem to be dismissing her credentials, but avian artists study their subjects in great deal; Science gave another avian artist a platform for providing his inputs on this issue.

How you stand in the birding community isn't relevant. The issue here isn't to look at a pretty picture and decide if it matches a bird that appears in a field guide. The issue is to analyze the videos using logical arguments that are based on any available information, such as avian flight mechanics, the statistics of flap rate, concepts in probability, flight speed, wing and other body proportions, flap rate models, historical accounts of the Ivory-billed Woodpecker, comparisons with the Pileated Woodpecker and other Campephilus woodpeckers, etc.

I didn't regard my reply as disingenuous and defensive, but were you expecting me to be Mr. Nice Guy after you included a remark about Bigfoot?
 

fishcrow

Well-known member
Thanks again and well done for continuing the debate in the face of adversity.

Wings look dark in some frames and pale in others, which is not in the least bit unusual for a host of species, and I couldn’t possibly discern more detail than that with footage of such desperately poor quality. For what it’s worth, my money would be on a Belted K.

If I ever come face to face with an IBW, I will not be concentrating on eye colour. And I don’t plan to send the British Birds Rarities Committee a cartoon of me not seeing a bird as evidence of the next rarity I find (if indeed there ever is another one!). I do appreciate the cartoons are only illustrative, they just seem really odd in a scientific paper - and they seem to do more harm than good.

I tend to agree with all the negative points made so far on here I’m afraid.

Really hope we’re all wrong and they are out there. Possibly at odds with others, it wouldn’t even need a photo for me, just a convincing description that rang true and had all the hall marks of an experienced and authentic birder, preferably one with a decent reputation (and I know nothing of yours I’m afraid so I remain neutral there).

Everyone has their own opinion. Other scientists have told me that they love the illustrations. I would certainly enjoy seeing recreations of the scenarios of other observations of this species. The difference in the color of the eyes of the large woodpeckers and the surrounding plumage is a major difference between the large woodpeckers. I did observe this difference in the field, it was a very interesting observation, and it is relevant to report as many details as possible of an observation. The bird in the 2008 video flew near reference objects, and it was possible to pin down its location by triangulation since the bird and its reflection appear in the video. A reference object that was placed in the scene and a photo was obtained and compared with the video. The wingspan is substantially greater than the wingspan of the Belted Kingfisher, and there is no trace of the strong dorsal field marks on the wings of that species. My analysis of the video is based on logical arguments. You have expressed no logical reasons for betting on the Belted Kingfisher.
 

fishcrow

Well-known member
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.
In this case, it is a statistical slam dunk that it's not a Pileated Woodpecker according to an expert in the application of statistics.
 

McMadd

You should see the other bloke...
The difference in the color of the eyes of the large woodpeckers and the surrounding plumage is a major difference between the large woodpeckers. I did observe this difference in the field, it was a very interesting observation, and it is relevant to report as many details as possible of an observation.

You've seen it well enough to discern eye colour yet have no clear photograph or video despite years of effort? A species widely believed extinct that you are searching for evidence to disprove that hypothesis. That you go into the field equipped with camera traps, 'reference objects' and statistics to help you...yet you saw it well enough wi discern the eye colour...

Sorry dude, that boat ain't floating...

Not to mention the oh so shy Sanger Tract Birds sitting on researchers heads at the nest site...yet one human generation later they have evolved stealth-like cloaking traits to stop us obtaining clear photos or videos but do let you see the eye colour...

We did this to death on the other thread years ago...it's gone...let it go...
 

Hauksen

Forum member
Hi Mike,

In this case, it is a statistical slam dunk that it's not a Pileated Woodpecker according to an expert in the application of statistics.

You're using the concept of standard deviation outside the context where it's applicable, and that's an elementary fallacy.

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.

I'm a bit surprised I have to point this out to you as it's really a statistics 101 issue.

Regards,

Henning
 

Britseye

Well-known member
Which specific videos gave you trouble?

The independent experts whose comments on the videos appear in my papers include Bret Tobalske, who is widely regarded as THE expert on woodpecker flight mechanics, and Julie Zickefoose, an avian artist whose paintings of the Ivory-billed Woodpecker have appeared on the covers of major publications in ornithology. You seem to be dismissing her credentials, but avian artists study their subjects in great deal;

How you stand in the birding community isn't relevant. The issue here isn't to look at a pretty picture and decide if it matches a bird that appears in a field guide. The issue is to analyze the videos using logical arguments that are based on any available information, such as avian flight mechanics, the statistics of flap rate, concepts in probability, flight speed, wing and other body proportions, flap rate models, historical accounts of the Ivory-billed Woodpecker, comparisons with the Pileated Woodpecker and other Campephilus woodpeckers, etc.

I didn't regard my reply as disingenuous and defensive, but were you expecting me to be Mr. Nice Guy after you included a remark about Bigfoot?

1)The downloaded files below gave the attached error message.

flaps-slow.avi

and flyunder-approach.avi


2)Experts schmexperts. I wore a T-shirt with a lovely painting of an Ivory-billed Woodpecker by internationally renowned bird artist Dave Sibley for the World Series of Birding in 1999. This is what Mr Sibley had to say regarding the claimed rediscovery in 2004....



Noah Arthur says

December 11, 2014 at 11:44 PM

Hi. One thing I haven’t seen mentioned anywhere on this site is the wingbeat frequency in the video. To me that is the single most convincing feature. I’ve read that the bird in the video flaps its wings too fast for a Pileated (at least, faster than the wingbeat frequency seen in any video of a Pileated). And wingbeat frequency is a characteristic that seemingly wouldn’t be affected by poor video quality: even if the video is too blurry to see plumage details, you can still count the bird’s wingbeats! Is there any reason why this doesn’t hold water? I do wonder if video recording might artificially speed-up or slow-down the action, but I’ve never heard of that happening…

Reply
David Sibley says

December 15, 2014 at 3:14 PM

Hi Noah, As far as I know there is no reason to doubt the accuracy of the wingbeat rate shown in the video, the issues are with variability in wingbeat rate within any species, and with using it as an ID feature. There are very few measurements of wingbeat frequency to start with, and even fewer of a Pileated Woodpecker taking flight and climbing at the same time, as this bird does. It was wrong to claim an identification by comparing these wingbeats with the slower wingbeats of a Pileated in normal level flight. And there are now some videos that show Pileateds taking off with the same wingbeat rate as this bird.

The wingbeat rate of Ivory-billed Woodpecker is entirely unknown (we can’t even be sure the single audio recording is a bird in flight), and everything that is known about wingbeats suggests that the heavier species (Ivory-billed Woodpecker) would have a slower wingbeat, not faster. If Ivory-billed Woodpecker flapped faster than Pileated I think that would be just as surprising as rediscovering the species (although less momentous, of course). The idea that Ivory-billed Woodpecker had a fast wingbeat seems to have become “common knowledge”, but that is still unknown. There’s just no solid evidence for it.

In summary, the wingbeats in the Arkansas video are within the normal range for Pileated, and anything else is pure speculation.

3)Using logical arguments, then...if the wing-beat rate of Ivory-billed Woodpecker is 'entirely unknown', it cannot be compared with anything. Ergo..............end argument.

Sincere best wishes. I do hope you are successful in your quest for evidence that will convince the World of the continued existence of IBW.
 

Attachments

  • P1020066.jpg
    P1020066.jpg
    336 KB · Views: 43

fishcrow

Well-known member
1)The downloaded files below gave the attached error message.

flaps-slow.avi

and flyunder-approach.avi


2)Experts schmexperts. I wore a T-shirt with a lovely painting of an Ivory-billed Woodpecker by internationally renowned bird artist Dave Sibley for the World Series of Birding in 1999. This is what Mr Sibley had to say regarding the claimed rediscovery in 2004....



Noah Arthur says

December 11, 2014 at 11:44 PM

Hi. One thing I haven’t seen mentioned anywhere on this site is the wingbeat frequency in the video. To me that is the single most convincing feature. I’ve read that the bird in the video flaps its wings too fast for a Pileated (at least, faster than the wingbeat frequency seen in any video of a Pileated). And wingbeat frequency is a characteristic that seemingly wouldn’t be affected by poor video quality: even if the video is too blurry to see plumage details, you can still count the bird’s wingbeats! Is there any reason why this doesn’t hold water? I do wonder if video recording might artificially speed-up or slow-down the action, but I’ve never heard of that happening…

Reply
David Sibley says

December 15, 2014 at 3:14 PM

Hi Noah, As far as I know there is no reason to doubt the accuracy of the wingbeat rate shown in the video, the issues are with variability in wingbeat rate within any species, and with using it as an ID feature. There are very few measurements of wingbeat frequency to start with, and even fewer of a Pileated Woodpecker taking flight and climbing at the same time, as this bird does. It was wrong to claim an identification by comparing these wingbeats with the slower wingbeats of a Pileated in normal level flight. And there are now some videos that show Pileateds taking off with the same wingbeat rate as this bird.

The wingbeat rate of Ivory-billed Woodpecker is entirely unknown (we can’t even be sure the single audio recording is a bird in flight), and everything that is known about wingbeats suggests that the heavier species (Ivory-billed Woodpecker) would have a slower wingbeat, not faster. If Ivory-billed Woodpecker flapped faster than Pileated I think that would be just as surprising as rediscovering the species (although less momentous, of course). The idea that Ivory-billed Woodpecker had a fast wingbeat seems to have become “common knowledge”, but that is still unknown. There’s just no solid evidence for it.

In summary, the wingbeats in the Arkansas video are within the normal range for Pileated, and anything else is pure speculation.

3)Using logical arguments, then...if the wing-beat rate of Ivory-billed Woodpecker is 'entirely unknown', it cannot be compared with anything. Ergo..............end argument.

Sincere best wishes. I do hope you are successful in your quest for evidence that will convince the World of the continued existence of IBW.


I don't know why you would be looking at avi files. All of the movies in the supplemental material of my papers are in mov and mp4 format. The analysis of the 2008 video does not require any information on the flap rate of the Ivory-billed Woodpecker. It is based on ruling out the Pileated Woodpecker on the basis of its known flap rate.

As mentioned previously, avian artists have some relevant expertise in the analysis of video footage. They study in great detail subtle characteristics of birds, such as those that Zickefoose pointed out in the 2006 video. Her analysis is far more relevant to this issue than anything that Sibley has contributed. The comments that you copied and pasted have no relevance to the analysis of my data. So what is your point?

You seem to be grasping at straws trying to find a flaw in the analysis of the videos. Nobody has put the slightest dent in any of the analysis. Nothing of any value has come out of the discussions in this thread. I'm not going to waste any more of my time with it.
 

Britseye

Well-known member
Nobody has put the slightest dent in any of the analysis. Nothing of any value has come out of the discussions in this thread. I'm not going to waste any more of my time with it.

That's great, then. We can all look forward to the official announcement that the species is alive and well in the forthcoming weeks. It's so nice with all the negative stories we hear of declining bird populations, to have this one heart-warming story of rediscovery to offset all the doom and gloom. Jolly well done to you, I say, and a curse on those jaded naysayers who only believe the evidence of their own eyes.
 

etudiant

Registered User
Supporter
I don't know why you would be looking at avi files. All of the movies in the supplemental material of my papers are in mov and mp4 format. The analysis of the 2008 video does not require any information on the flap rate of the Ivory-billed Woodpecker. It is based on ruling out the Pileated Woodpecker on the basis of its known flap rate.

As mentioned previously, avian artists have some relevant expertise in the analysis of video footage. They study in great detail subtle characteristics of birds, such as those that Zickefoose pointed out in the 2006 video. Her analysis is far more relevant to this issue than anything that Sibley has contributed. The comments that you copied and pasted have no relevance to the analysis of my data. So what is your point?

You seem to be grasping at straws trying to find a flaw in the analysis of the videos. Nobody has put the slightest dent in any of the analysis. Nothing of any value has come out of the discussions in this thread. I'm not going to waste any more of my time with it.

Honestly, Fishcrow, no need to argue the details, we all recognize that you have been pursuing this task for more than a decade with great dedication.
However, what may seem ample evidence to you after all that time and effort is just not enough for others who are very much aware of other sightings which never gave a positive answer.
This is a species that has not been demonstrably seen since the 1940s, despite lots of people looking. Recognize it will need much more than a flight pattern assessment to persuade others that it is still extant. Good photos are the minimum to get people to accept that an extinct species is still extant.
 
Status
Not open for further replies.
ZEISS. Discover the fascinating world of birds, and win a birding trip to Columbia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia
ZEISS. Discover the fascinating world of birds, and win a birding trip to Colombia

Users who are viewing this thread

Top