Ilya Maclean
charlatan
Yes, there are many uncanny similarities between the Slender-billed Curlew and the Ivory-billed Woodpecker.
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Yes, there are many uncanny similarities between the Slender-billed Curlew and the Ivory-billed Woodpecker.
have you, perchance, noticed any differences between the two cases?
Rob
Right. Being a typical Salar, I'll rise to the bait.
Now why do I think it's immaterial what differences I may have noticed, because you're going to tell me anyway!
salar53; said:Yes, there are many uncanny similarities between the Slender-billed Curlew and the Ivory-billed Woodpecker.
And the arguments rage over both species.
WHAT????
There is absolutely nothing in common! In one case there is well-defined multi-observer photographic evidence... that still isn't/may not be enough to confirm the record, and in the other there is a whole great heap of heresay....
Or do you mean that in all likelihood they are both doomed if not already extinct?
Ah - I see a few other people have already got here
allometry
Forget Julian Huxley - your gonna need some serious help from Aldous Huxley's medicine cabinet to get to see an IBWO in the latest Pearl Video.
Luke
Jane said >>>>whole great heap of hearsay....<<<<
You never spoke to anyone that has seen a putative Giant Woodpecker,? you talk to Dave and there are others here too that posted today that have had up to 3 encounters.
or to slightly misquote Blake:
'when the doors of perception are cleansed everything will appear to man as it really is, Pileated.'
Oh brave new world that has such birders in it
Rob
The Doors of Perception? Brave New World? Aldous Huxley?
Well you know of course that Aldous Huxley was stoned out of his mind when he wrote "The Doors of Perception."
no, he was quite straight at the time and recounting his experiences
Rob
Hi Jane,Spoken accounts are indeed just hearsay.
No argument from me there. In fact for IBWO at this point I don't think any written report alone would be uniformly accepted now without including good photo documentation and multi-person confirmations. Follow up confirmations would likely also be required for across the board acceptance. The most that even the best written report alone might do is prompt attempts at confirmation.There are no written descriptions that pass muster. That is fact.
I went ahead and took a shot at calculating wingspan from this "nearly directly below" image, which shows the wingspan pretty much fully extended in the reflection.
Using the zero point from before, I measure 40 degree view angle from the tree to this reflection. So from 75 feet up, the reflection would be 63 feet from the tree. Doing the calcs like before, I get 97.8 feet line of sight to the reflection, plus 12.6 from reflection to bird, so 110.4 feet total. The width of the wingspan in this image at 110.4 feet away would be 26.4 inches, but that is not yet adjusted for the angle of the water.
The line-of-sight is 50 degrees up from the water. Therefore the vertical component of the wingspan has to be increased by 1/sin(50) = 1.3 ... I did the calculation for adjusted wingspan like this:
W' = SQRT((W*sin(55.3))^2+(1.3*W*cos(55.3))^2) = 29.2
View attachment 143252
Wingspan estimate based on this calculation then is somewhere around 26 - 32 inches. [edited from original post to +/- 10%]
BTW, I found another mistake in my earlier calcs. The 36 degrees that I mentioned before was the vertical FOV for the camera shot. The video by comparison scales to about 30.6 degrees VFOV... Kicks my speed calculations back a bit closer to where I started:
camera height, bird speed
80, 31.6
75 ft, 29.6 mph
70, 27.6
65, 25.7
60, 23.7
I also ran it through from Point-2 to Point-3 (where the reflection is for the wingspan calc). At Point 3 I get a bird height of 9.7 feet above the water, and from Pt 2 to Pt 3 I get:
camera height, bird speed
80, 33.2
75 ft, 31.1 mph
70, 29.0
65, 27.0
60, 24.9
- Dave
OK, this is all very interesting, but I just can't believe the process has an error of only 10 percent. Do we really even know the height of the camera to within 10 percent? We hear that it is "75 feet"--that sounds like a round figure to me, but perhaps I missed that. Given the complexity of the measurements and the uncertainties on multiple levels, to really get a good handle on the error, it seems like one should video some birds of known identity under similar conditions and see how that works out.I went ahead and took a shot at calculating wingspan from this "nearly directly below" image, which shows the wingspan pretty much fully extended in the reflection....
Wingspan estimate based on this calculation then is somewhere around 26 - 32 inches. [edited from original post to +/- 10%]
OK, this is all very interesting, but I just can't believe the process has an error of only 10 percent. Do we really even know the height of the camera to within 10 percent? We hear that it is "75 feet"--that sounds like a round figure to me, but perhaps I missed that.
Given the complexity of the measurements and the uncertainties on multiple levels, to really get a good handle on the error, it seems like one should video some birds of known identity under similar conditions and see how that works out.
I don't think a wingspan measurement would prove anything. It might help discount some things, but like you say, you'd need some better idea of accuracy before doing that.Irrespective of the size of the errors, I don't see what a wingspan measurement proves, given the images, which don't show any plumage specific for an Ivory-billed Woodpecker that I can see. (Where are the white stripes on the back?) I did a little Internet searching and found some wingspan values:So even given an error of 10 percent, which I think is pretty darn narrow for a measurement under field conditions, several species of birds expected to be in that habitat fit the bill--Pileated, Wood Duck, Green Heron, ...
- Ivory-billed Woodpecker 30-31 inches (here)
- Pileated Woodpecker 29 inches (same source)
- Belted Kingfisher 19-23 inches (here)
- Great Blue Heron 66-79 inches (here)
- Anhinga 43 inches (here)
- Black-crowned Night Heron 45-46 inches (here)
- Wood Duck 26-29 inches (here)
- Green Heron 25-27 inches (here)
If the error is a bit larger, say 20-30 percent, which my "gut" tells me is reasonable on this sort of thing, then all sorts of birds are consistent with the calculated wingspan. (Maybe even 50 percent is reasonable.) Somebody suggested Belted Kingfisher, and the wingspan is really not that far off from the best estimate above--about 20 percent below the midpoint, and only 10 percent below the lower limit, 26 inches. The bird in the video, to me, has a flight pattern consistent with a Kingfisher (among many other things), which really does have a flight pattern rather like a woodpecker--tucking the wings in close to the body between flaps.
Why am I not surprised that the figure of 75 feet was not firm. It was probably lower--most people overestimate heights when up in a tree, a building, etc.I contacted Mike and he said he thought 75' was about right, based on laser rangefinder measurements he had done previously, but he hasn't measured it yet. He is planning on taking measurements at the site, and I expect I'll get the info. The way I'm doing this approximation, the values all go up or down by a proportionate percentage based on height.
My point was that the whole thing is pointless--and you are agreeing with me. IBWO cannot be told from any number of other things by the wingspan.I don't think a wingspan measurement would prove anything. It might help discount some things, but like you say, you'd need some better idea of accuracy before doing that.
Identifying an Ivory-billed Woodpecker from a video, if the video is of any decent quality, is a simple problem--the bird's field marks should stand out like a sore thumb. Just like everyone else (Cornell, Auburn, Mary Scott, Kulivan), Fishcrow claims to have seen the bird real well, even multiple times, but just can't get the documentation. Over, and over, and over... This has been going on for 60 years.I haven't done any detailed error approximation, because I don't think it's worth the effort without some actual measurements from the site. Even then, I'll be interested in redoing the calc, but I don't know how deep into error quantification I want to get... It's not a simple problem.
I don't have Fishcrow's tree-climbing skills--or a desire to develop them--though I can take decent photographs, and I have even documented some rare birds with them. Just because Fishcrow is brave about scaling trees, however, does not mean he's finding Ivory-billed Woodpeckers.If you want to send me some test stills to try, I'd be up to give it a go as a test. It'd be intersesting to see how far off I'd be.