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Swift ID Whitburn Co.Durham (1 Viewer)

I'm good thanks Alan..

For a fairer comparison I've used a photo where the Whitburn bird has its primaries fully open, to the point of separating. Look at the relative lengths of the outer three primaries.

Interesting to see the different structure of the underwing coverts. The Whitburn bird's greaters are, what, twice the length of the Pallid's? Are the Pallid's feathers fully grown? Do these feathers vary in length between different ages and/or between species of swifts?

Folks who have only seen Pallids with the milky background colour (like typical birds in Spain) may expect all Pallids to look like that. They don't. Subspecies, individual variation, age and light conditions all contrive to make Common/Pallid a far more difficult problem than it seems when you first see a few milky adults in bright sun and decide it's not so hard an ID.

I think the Whitburn bird is a Common, but it's not easy.
 
I was intrigued by the radically different apparent exposed lengths of the greater underwing coverts (the feathers that overlie the primaries anyway) between these two birds. A feature? Age? Moult? Nonsense?

cheers, a

One is an upperwing and the other an underwing... might explain it (but the primary lengths are the primary lengths whether seen from above or below :eek:) )
 
Hopefully this works big file (bigger than birdforum limit and Google Docs hosting limit so I'm winging this!) (excuse the pun just noticed)

courtesy of Ross Ahmed
 
Birds I took in Spain in May (adult, spring...relevant??) show the scaling that is apparently made up of a dark base with a pale fringe?

I wonder if everyone is talking about bases, tips and fringes in the same way?

here for example below is a pallid showing pale bases to dark body feathers, which in turn have a thin pale terminal tip or fringe

hence reference in Ross Ahmed paper to "not just pale tips to the feathers, but also pale base (unlike apus)"

but when saying "unlike apus" I'm thinking RA may not mean that the pale base is actually absent in apus- just less obvious/extensive?

some of the reject pallids /re-id commons posted above show pale marks that to my eye only make sense as exposed feather bases, not thin terminal tips or fringes
 

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You don't fool me Ed...that pic is obviously of a cod fish...;)

But seriously...it would be interesting to see various pix of swift sp underpart feathering taken from different lighting angles...

In this instance i refer to 'tips' as fringes by the way...[perhaps i shouldn't but i do]..!

ps...maybe i'll go down my local museum and photograph a few skins...[i was going to do that anyway regard certain snipe ID]...:smoke:

Keep up the fine work folks....!

http://username-beast.blogspot.com/
 
I wouldn't normally quote the competition but I note that RBA have just added their daily summary that reads "the only new rarity today was a smart Pallid Swift at Whitburn" ;)

Also interesting that the Birdguides 'Review of the Week' today states it as a Pallid, avoiding the 'probable' tag of those at Filey and Winterton... Any trump cards still to declare Alan? ;)
 
Here are close ups of two definite A.apus and the Whitburn bird (right). As far as I can tell both show a stronger suggestion of pale bases than the Whitburn bird - so either A.apus can show pale bases or more likely its not impossible for there to be a photo or reflective artefact that gives the appearance of pale bases



I'm sure but can't yet prove much of the visual effect can't be explained by reflection of curved feathers.... (off to look at eg hummingbirds) where its should be easier to see
 

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I didn't get as far hummers - just compare these two shots (consecutive file nos) to see what being illuminated from a different direction does the apparent shades of base and tip of the belly feathers
 

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When you need to be 100% sure in the context of a vagrant,I'd agree. You'd want to verifiably record most of the features and nothing contradictory.

Surely we are generally talking about the situation in Autumn (and probably mainly wrt juveniles)? They are a doddle in Spring....aren't they? Well, that one in Liverpool was anyway.

a
 
One is an upperwing and the other an underwing... might explain it (but the primary lengths are the primary lengths whether seen from above or below :eek:) )

I'm sure you are right! Interesting that they are so different above and below. Longer above creating more curved wing in cross-section and more lift perhaps?

cheers, a
 
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