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IVORY-BILLS  LiVE???!  ...

=> THE blog devoted to news and commentary on the most iconic bird in American ornithology, the Ivory-billed Woodpecker (IBWO)... and... sometimes other schtuff.
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"....The truth is out there."

-- Dr. Jerome Jackson, 2002 (... & Agent Fox Mulder)

“There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.”

-- Hamlet

"All truth passes through 3 stages: First it is ridiculed. Second, it is violently opposed. Third, it is accepted as self-evident."

-- Arthur Schopenhauer






Thursday, September 01, 2005

 

-- The 'Jizz' of a Bird --

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As most readers likely know there is in birding a notion of the "jizz" of a bird -- an overall impression (gut reaction, or 'gestalt' as some would say) one gets in even a brief view of a bird -- based on fleeting features of perceived color, shape, size, and movement, in some combination. It may result in a specific ID, or simply ruling out various IDs.
Unlike many optimists, I don't find Cornell's acoustic evidence for Ivory-bills in the Big Woods compelling. And the Luneau film clip remains rightly very controversial. Upon first viewing it, the "jizz" of that bird said to me "melanistic white ibis!" -- I STILL haven't ruled that out!!! (Cornell claims the bird must be a woodpecker, because it is perched on the side of a tree at beginning of clip, BUT it is on the OPPOSITE side of the tree and thus not entirely clear whether it is grasping the tree's trunk OR perched atop a possible branch nub, though I tend to accept the Lab's analysis). Even without knowing of Cornell's calculated measurements for the bird, it appears, to my eyes, (pretty clearly) TOO large for a Pileated, but this admittedly, is subjective. Moreover, on BOTH the up and down wing strokes the bird seems to reveal far TOO MUCH white for a Pileated -- indeed, I'm amazed at those who now argue the bird could actually be a NORMAL Pileated, and need not even be leucistic!!?? In the end, one can only play probabilities, and given a hesitant acceptance of Cornell's measurement techniques/results and this bird's 'jizz,' I feel the probability is WELL over 50% for Luneau's speciman being an Ivory-bill.
BUT... the video isn't even important to me. The MOST compelling evidence, for me, remains the 7-15 sightings by experienced birders who were immediately struck by the NON-Pileated "jizz" of the bird-in-question. It's size/bulk, amount and pattern of white, and in some instances flight style, all shouted out 'something different!' -- 'like a Pileated, but NOT a Pileated!' This consensus is weighty, especially when combined with all the other evidence over decades for the bird's survival.
When David Kulivan reported 2 Ivory-bills at Pearl River in 1999, doubters clamored for multiple, or more credible, witnesses. Now, in AR. they have THAT, but once more the bar has been raised. I fear, some skeptics won't be convinced unless, as in 1932, another Mason Spencer-like figure comes forth to plop a dead, warm Ivory-bill carcass on the desk at the AR. Game and Fish Commission and declare, "hey fellas, here's that dang bird ya' all been lookin' fer." Deja vu, anyone?!
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Comments:
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Really interesting site with video of many species. Most interesting for this forum is a video of the Magellanic Woodpecker, Campephilus mageallnicus performing a double-rap display. Very neat.

http://www.hbw.com/ibc/phtml/especie.phtml?idEspecie=3943
 
Oops, should have previewed those links. Trying again:

The Internet Bird Connection has lists of species with linked video clips. Of most interest for this forum:

list of woodpeckers and page on Magellanic Woodpecker. One of the Magellanic shows it doing the "double-rap" display.
 
Size comparisons, from Winkler, et al., Woodpeckers, an Identification Guide, Houghton Mifflin, 1995. Pileated are measurements for southern race, D. p. pileatus, except for weight, which is for northern race. IBWO for nominate race, C. p. principalis (North American, i.e., not the Cuban race)

Pileated/Ivory-billed
wing: 214-235/240-263 mm
tail: 140-161/147-166 mm
bill: 41-53/63-73 mm (male)
tarsus: 31-35/40-46 mm
weight: 250-340/circa 450-570 g

So, ballpark comparisons, wings of IBWO about 10% longer than Pileated. (Odd, I thought they were reported to be much longer.) Tail similar in length, bill rather longer in IBWO, esp. in male, IBWO was estimated to be much heavier, up to twice weight of Pileated. I gather there aren't good weight measurements of the IBWO.
 
Better size comparisons for Pileated Woodpecker versus Ivory-billed Woodpecker, from Coues, Key to North American Birds, 5th ed., 1894

Units are centimeters (cm), as opposed to mm quoted in my previous post:
PIWO/IBWO
Length: 38-48/48-53
Wingspan (extent): 64-76/76-84
Wing: 20-25/25-27
Tail: 15-18/18-20
Bill: 3.8-5.1/6.4-(not given)

Note that Coues does not break out the different races of the PIWO. He says that northern birds average much larger than southern.

He also states in both species accounts that the size of each species is quite variable, and that the female IBWO is smaller than the male. He states that the IBWO is "common in the dark heavily wooded swamps, but very wild and wary, and difficult to secure." (The original edition of Coues' work was published in 1872--I think the IBWO was getting scarce by 1894, according to other sources.)

Looking at the numbers and taking ratios, one gets similar results for Length, wingspan, and wing length--the largest PIWO just overlap the smallest IBWO in wingspan and length. The largest IBWO would be up to 30-40% larger than the smallest Pileated.

The figures I quoted previously on weights (estimated for the IBWO) are interesting. The estimated ranges are PIWO 250-340, IBWO circa 450-570 grams. The weight of an IBWO would be estimated to be 1.7X to 2.3X that of a PIWO.

Looking at the numbers and taking ratios, one gets similar results for Length, wingspan, and wing length--the largest PIWO do not quite overlap the smallest IBWO, the latter would be about 10% larger in wingspan or length. The largest IBWO would be up to 30-40% larger than the smallest Pileated.

The figures I quoted previously on weights (estimated for the IBWO) are interesting. The estimated ranges are PIWO 250-340, IBWO circa 450-570 grams. The weight of an IBWO would be estimated to be 1.7X to 2.3X that of a PIWO.
 
Correction: the largest PIWO would just overlap the smallest IBWO in wingspan and length, according to Coues' figures.

The numbers from Coues are not really "better" than those from Winkler, they just included total length and wingspan, not given in Winkler.
 
Of interest: THE IMPERIAL IVORY-BILLED WOODPECKER, Campephilus imperials (Gould), BY E. W. NELSON--PDF (text and plate) reproduced from The Auk, volume 15 #3 (1898). This is an interesting article, describing the rather social nature of the Imperial Woodpecker in the fall and winter. Also has descriptions of flight pattern. The article describes the Imperial's calls as being apparently rather soft at close range, but carrying far through the forest, audible for about a mile. There are no descriptions of feeding habits that I noticed. Nelson found the birds in beautiful highland pine forests. Most of that habitat has been destroyed in Mexico, I understand.

Incidentally, there is some discussion of the putative last reports of this bird in A Naturalist's Mexico, by Roland H. Wauer--rather depressing reading.
 
Links of interest on the Pale-billed Woodpecker, Campephilus guatemalensis from the neotropics:

Animal Diversity Web: Pale-billed Woodpecker, Campephilus guatemalensis. That page has links to various sounds. Most interesting is recording of the double-rap. The two raps are right on top of each other.

Sounds and sonogram from Cornell, of course.

video clip--very nice, but no drumming. Shows the bright eye, white stripes on the dorsum, and the pale yellowish bill.

I saw a couple in Costa Rica, but never could pick out the vocalizations or rapping from the din of other unfamiliar birds and mammals.
 
Aha, yet more woodpecker videos, from Many Birds, see the page on woodpeckers--these include a Pileated in flight, Lineated Woodpecker (neotropical, genus Dryocopus) and Pale-billed Woodpecker (neotropical, genus Campephilus). It's rather hard to compare the video of the Pileated with the Cornell IBWO video because the quality is so much better, like, in focus! Has quite a bit of technical discussion about shutter speeds, video formats, etc.

Ah, that Pale-billed is so beautiful.
 
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