Tuesday, March 11, 2008

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Finally, an update (reporting to the end of Feb.) from Cornell's Mobile Team covering time spent in the Pearl River region (Louisiana) followed by week or more around the Pascagoula (Mississippi), one of the favored spots from last season. They are apparently now in southern Florida (unless they've already left to travel further north) and possibly areas that didn't get much coverage last season (no Ivorybill encounters reported thus far):

http://www.birds.cornell.edu/ivory/current0607/0708TravelLogs/MSTlog/document_view

Feel the need to address one other issue lest it be confusing to others out there. The John Agnew sighting linked to yesterday includes a sketch of the underwing of the bird he saw, which some, elsewhere on the Web, are erroneously claiming is a WRONG sketch for an Ivory-bill. There may or may not be problems with John's report, but the sketch is reasonably dead-on! This matter has been discussed at length before; the underwing as perceived in the field will not necessarily (or even usually) match the depictions done in field guides which are based upon museum specimens in the hand; in short, the white along the leading underwing edge (prominently depicted in field guides) doesn't necessarily appear to a typical observer. Professional artist Julie Zickefoose (among several) explained it over two years ago on my blog as follows in reference to a famous Arthur Allen photo of the IBWO:

"Here's what's happening in that photo, and in life:
The famous (and only good) Arthur Allen photo of the flying ivory-bill was taken from beneath, with bright overhead lighting. As such, the white secondaries and inner primaries are illuminated and clearly read as white. The white lining of the underwing, which includes the underwing coverts and feathering along the ventral surface of the patagium, does not appear white in this photo because it is in shadow, and the light is not shining through it. If you look at any photo of a flying bird, taken from below and brightly lit from above, light is able to pass only through the flight feathers along the trailing edge of the wing, since there's only one layer of feathers there. Light really can't pass through a patagium, since it's heavily feathered, and there's skin and bone to further block that light. So, confusingly, this "wing lining" appears dark in the photo. But rest assured that Roger Peterson and other careful bird painters did get it right. And field guide plates emphasize local color rather than artifacts of light, because their mission is to show what color the bird actually is, rather than the color it may appear to be."
How many white primaries an observer might be expected to see in a flapping Ivorybill overhead is also difficult to know, given that, by far, most of the white is confined to secondaries in the underwing. And one thing is for sure, Agnew's sketch, as drawn, certainly couldn't have depicted a Pileated Woodpecker, but yes, it does fairly match an Ivory-bill.
As I've said before, with so many liars or fools apparently out there (in the skeptics' assessment), it's a wonder any data from Christmas or spring bird counts is ever taken seriously given its wholly unrigorous nature. Show me a report of 20 Starlings on a Christmas count and I'll give you a dozen different ways that report might be false or mistaken (yet with no verification whatsoever, most of us will accept the report no questions asked... because birding ain't rocket science and never will be).

To end on a lighter note, Martin Collinson, has produced one fine hat for birding (spiffy!!) at his site. If he can just have it done in green camo maybe it could become requisite attire for swamp searchers everywhere... or... maybe not.
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2 comments:

Anonymous said...

Thank you for sharing this perspective!

cyberthrush said...

glad you found the hat useful!... ;-)