Monday, October 09, 2006

Time saving suggestion...

...for those who might report a sighting of an Ivory-billed Woodpecker. Here's a couple of things you should NOT include in your write-up; leaving these out will save grief and time for the rest of us.

1. "It was bigger than a Pileated."

If you didn't see the bird with a Pileated, at the same time and distance, don't say this. Neither you nor I nor anyone else can really judge this. I've seen thrushes turn into warblers when I got my binoculars on them, and swallows turn into raptors. Sure, a gross size estimate is fine -- "A very large black-and-white woodpecker," that sort of thing. But other than that, tell us about the bird's shape and actions, not an unsupportable detailed estimate of its size. Did the neck and tail and wings look long or short relative to the shape of a Pileated? That's fine, an experienced oberver can judge this. Maybe these things gave "an impression of larger size;" that's fine, too. That's recognized as a subjective impression, not a quantitative estimate. But don't get everyone all riled up by saying "it was too big to be a Pileated" if there was no Pileated available for direct comparison.

2. "I don't know what it was, but it definitely wasn't a Pileated."

This one has been said far too many times; I have no idea wat it is supposed to mean. The main thing it says to me is that the observer is either (a) unskilled, or (b) trying to stay out of trouble. Either way, it's a wishy-washiness that doesn't cast a good light on the report. I mean, let's get serious here. If you saw the bird well enough to tell it was a big black-and-white woodpecker, and you are certain it wasn't a Pileated, well then, ferkrissakes, what ELSE could it be? Unless you are suggesting a zoo escape or unprecedented intercontinental vagrant. If you didn't see the bird well enough to be 100% sure it was an Ivorybill, then NO you are NOT sure it definitely wasn't a Pileated, are you? And if you aren't even sure it was a large black-and-white woodpecker, then there's no sighting to discuss at all. So please, no more of this hedging and shuffling. Either conclude the bird you saw was an Ivorybill, and tell us this, or present your sighting without any definite conclusions and let us form our own opinions (which we will do anyway, of course).

Thank you for your attention. Here endeth the rant. Have fun in the swamps.


At 7:58 AM, Blogger cyberthrush said...

As you likely already know Bill I somewhat disagree with your #1 above: for experienced birders, I believe the so-called "jizz" of the bird (which includes size) is very significant (often moreso even than individual field marks). If someone thought they saw an IBWO and had all the field marks right, BUT then said it was definitely SMALLER than a Pileated, I would find that very discrediting of their report. If they noted no size differential, then size would be unimportant. But if they were well acquainted with PIWOs or had seen one 5 mins. earlier, and then reported another black-and-white woodpecker definitely larger than a PIWO I believe that is an important piece of info -- certainly not definitive, but an important add-on worth reporting, even though more specifics about size/shape would be preferable.

At 8:21 AM, Blogger Bill Pulliam said...

The experience of many birders shows that our estimates of absolute sizes of birds in the field are heavily based on our intuitive presumptions about what that bird is likely to be. On beyond that, human distance perception is just not that good. If you can't tell the difference between 100m and 120m distance, how are you going to judge the difference between 30 cm and 36 cm in length? A bird can easily have a "seems larger" jizz without actually being larger. The things we are good at percieving are shape and pattern. We can make fine discernments about small differences in these. We need to focus on these and not cloud the issue with something that we know humans are demonstrably bad it, which is gauging size and distance.

At 6:21 PM, Blogger cyberthrush said...

Bill said: "The experience of many birders shows that our estimates of absolute sizes of birds in the field are heavily based on our intuitive presumptions about what that bird is likely to be."

I don't want to beat a dead horse (too much), but this is a somewhat important point to me... if the above is true, most people's intuitive assumptions of a large black&white woodpecker is going to be "pileated" -- all the MORE reason to take note if someone thinks a particular bird was noticeably larger than a PIWO. When there is truly time to "focus" on a lot of other characteristics what you're saying makes a lot of sense, but when a quick glance is involved perception of size may be important (even if sometimes inaccurate). Often, in a quick glance, Cooper's are separated from Sharp-shins, or Hairys from Downies, solely based on size-perception with no comparison bird nearby (and I suspect, but can't prove, with a fair degree of accuracy).

At 6:31 PM, Blogger Bill Pulliam said...

Actually, and this is to the point, I *don't* separate Hairies and Downies or Coops and Sharpies based on size. I do it based on shape, plumage, and/or vocalizations. Size is unreliable.

At 7:04 AM, Anonymous Anonymous said...

Bill, I think you've made some good points. To be taken seriously, I think any report needs to be accompanied by, at least, good field notes containing a description of at least two of the following:
Dorsal stripes,
White secondaries,
White bill.
A decent photo,
A decent video.

One (perceived) field mark alone is far too unreliable, so much so that in my opinion it is nearly useless.


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