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Raptor, Doğubeyazıt Turkey (1 Viewer)

The essential question is "when is a feather long enough (compared with others) to be considered a finger?" Different people and circumstances provide different answers.
Hoorah 👍🏻🏅 This is my point. Hence we need a definition of 'finger'. I think there is more to it than simply 'length' - however that would be defined...
 
It's an interesting point about yellow-billed kite. However, if I saw this I'd think there were 6 fingers:
ML204705501 Black Kite (Yellow-billed) Macaulay Library

Very interesting case, yes it has obviously 6 fingers... well, the first genetic study on Yellow-billed Kite suggestes than more than one species might be involved. No more information since then... probably some discoveries to come. Your bird can simply be aberrant.
 
Very interesting case, yes it has obviously 6 fingers... well, the first genetic study on Yellow-billed Kite suggestes than more than one species might be involved. No more information since then... probably some discoveries to come. Your bird can simply be aberrant.
Or a hybrid? ;-)

(Does the word 'aberrant' encompass/include hybrids? Think not.)
 
Hoorah 👍🏻🏅 This is my point. Hence we need a definition of 'finger'. I think there is more to it than simply 'length' - however that would be defined...

Trying to have strict definitions to describe natural things is always a problem, as all limits we create are artificial. I'm an ornithologist since 30+ years, but I studied maths in university, so you can imagine how I feel it...

Teaching field ornithology since 20 years now, I can just advice you : I suggest you don't try to create a definition of "finger". The word "finger" itself, used to describe feathers that have nothing to do with real fingers, recall that this is not rigorous science, just a practical clue to help identification. I my classrooms, I would make exercises until it becomes obvious for all. It is much more efficient than producing a complicated definition.
 
Hoorah 👍🏻🏅 This is my point. Hence we need a definition of 'finger'. I think there is more to it than simply 'length' - however that would be defined...
Well the task is difficult but not impossible. As with almost everything else in biology the answers are relative, on a spectrum, slightly subjective etc (see e.g. any aspect of taxonomy). I think we just need to honour this with our commentary: not take "no of fingers" as a given but explain in each case ("I take this to have x fingers; I include feather y")
 
Strange discussion, Kuzeycem'scitation makes the definition very clear. How do you want to communicate between scientists if the basic definitions and nomenclature is not precise?
GSE and LSE have both 7 emarginated fingers (including P4), the difference is about length.
Depending on wind and wingload (flapping) Pallid Harrier may show 5 exposed outer primaries but never 5 fingers as P6 is never emarginated.
The definition is not the problem but A. what is visible in the field and B. knowledge of birdwatchers about nomenclature.
 
Fingers: emarginated tips of the longest primaries - Forsman (2016).
Good - at last we get to the point (y)
How do you want to communicate between scientists if the basic definitions and nomenclature is not precise?
Spot on. I fear I don't go at all for the approach of 'let's just look at lots of examples and it will become clear' (I paraphrase).
However, it was sloppy of me not to ask for a workable definition rather than merely a definition - because one clearly can't adequately distinguish emargination in a large proportion of the photos in which people gaily count fingers and claim IDs on that basis. Thus the Forsman definition is only arguably workable and is not fit to be used in the way that (sadly) many people do use it. And Tom is bang on the money in saying:
The definition is not the problem but A. what is visible in the field and B. knowledge of birdwatchers about nomenclature.
On this basis, many people should be using fingers for ID in far fewer cases than they are at present.
 
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