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Warbler, Aberdeen, Scotland (1 Viewer)
- Thread starter Andrew Whitehouse
- Start date
Bismarck Honeyeater
Barely known member
Nice. Fairly bogstandard Chiffchaff, I’m still waiting for my wintering ones to arrive, hopefully soon.
The responses probably reflect my own thinking, or confusion. In the field I assumed this was a Chiffchaff. There have been a few in the area recently. It wasn't in view for that long, but came close when it did (hence the fairly detailed photo).
I got less certain when I looked at the photos. The primary projection looks c. 80% to me, which is quite long for a Chiffchaff (perhaps an underestimate too, given the angle). I'm not great at reading emarginations but it I can only see three for sure. Maybe others can see the fourth - would be helpful if they can point it out if so. I guess it's probably a Chiffchaff, although it doesn't seem that bog-standard a one to me.
I got less certain when I looked at the photos. The primary projection looks c. 80% to me, which is quite long for a Chiffchaff (perhaps an underestimate too, given the angle). I'm not great at reading emarginations but it I can only see three for sure. Maybe others can see the fourth - would be helpful if they can point it out if so. I guess it's probably a Chiffchaff, although it doesn't seem that bog-standard a one to me.
Brian J Small
Well-known member
So Ken you can see ony 3 emarginations, but can't see that P1 is equal to length of primary coverts (=CC) rather than extending beyond them (=WW)?
WW showing length of P1 - http://www.tarsiger.com/images/karainio/Phylus16052006_3.jpg
In any case it looks like a Chiffchaff.
Brian S
Thanks for confirmation Brian.
KenM
Well-known member
A-a-a...Brian! I hadn’t picked up on that small point, presume that would override primary extensions that are clearly equal (almost) to the overlying tertials never seen that length on a Chiffy. How might you explain this anomaly, preferably by being more objective rather than sub (cos it looks like one).
Many thanks
Deb Burhinus
Used to be well known! 😎
I don’t know how the PP is being measured here to get ‘almost clearly equal PP’ here?
For the sake of those perhaps wondering what is being discussed and in an effort not to alienate general readership here, who might not be so familiar with assessing this measurement: - One of the diagnostic criteria for separating Willow Warbler from Chiffchaff is the extent the primaries extend beyond the tip of the last tertial ie the primary projection (PP) (refer to sticky at top of ID forum for topography and terminology!).
Willow Warblers generally have a PP extending from the tip of the longest tertial to the tip of the longest primary so as to be roughly the length from the base of the shortest tertial to the tip of the longest tertial.(Tertial length). In Chiffchaff, the length of the PP is from about half to about a two thirds of the distance again (PP) as is from the base of the shortest tertial to the tip of the longest tertial (tertial length)
To measure from the side as indicated in the link below
http://www.dublinbirding.ie/pages/features/chiff-willow.htm
In the OP it would look like this annotated attachment of the OP (hoping Andrew doesn’t mind his image being annotated!?)
The primary projection on Chiffchaff can vary in length, according to race (migrants?) and season (moult/feather growth/wear) but is generally within the parameters stated.
From, the annotated image, the Chiffchaff here has a PP falling well short of ‘equal length’ to the tertials and looks to be about two thirds which is in range for a Common Chiffchaff. Clearly not ‘almost equal’ to the tertial length and is clearly a Chiffchaff on plumage too!
For the sake of those perhaps wondering what is being discussed and in an effort not to alienate general readership here, who might not be so familiar with assessing this measurement: - One of the diagnostic criteria for separating Willow Warbler from Chiffchaff is the extent the primaries extend beyond the tip of the last tertial ie the primary projection (PP) (refer to sticky at top of ID forum for topography and terminology!).
Willow Warblers generally have a PP extending from the tip of the longest tertial to the tip of the longest primary so as to be roughly the length from the base of the shortest tertial to the tip of the longest tertial.(Tertial length). In Chiffchaff, the length of the PP is from about half to about a two thirds of the distance again (PP) as is from the base of the shortest tertial to the tip of the longest tertial (tertial length)
To measure from the side as indicated in the link below
http://www.dublinbirding.ie/pages/features/chiff-willow.htm
In the OP it would look like this annotated attachment of the OP (hoping Andrew doesn’t mind his image being annotated!?)
The primary projection on Chiffchaff can vary in length, according to race (migrants?) and season (moult/feather growth/wear) but is generally within the parameters stated.
From, the annotated image, the Chiffchaff here has a PP falling well short of ‘equal length’ to the tertials and looks to be about two thirds which is in range for a Common Chiffchaff. Clearly not ‘almost equal’ to the tertial length and is clearly a Chiffchaff on plumage too!
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dantheman
Bah humbug
Agree with the principle of pp etc, but as the bird in this pic is not actually side on, care has to be taken when making measurements (the wing is curving around to some extent). I think you also have to measure the length as presented, not in some arbitrary plane such as the horizontal (or maybe the illustration is just unclear.) 75% is not two thirds (it is three quarters).
Yes, I though that too. I'd also put the middle line a bit further left in Deb's picture and that would put it closer to 80% (about what I calculated from measuring). As the wingtip is slightly further away than the tertials, it's potentially slightly more than that rather than less.
According to van Duivendijk the primary projection range for the two is:
Chiffchaff - c.60%
Willow Warbler - 80-100%
I'm not disputing this bird being a Chiffchaff but it does seem to be quite a long-winged individual.
Deb Burhinus
Used to be well known! 😎
I have taken it to the right edge of the pale tip. Even allowing for a slight bend, it isn’t ‘almost clearly the same length’ (and the tertials (tips) also follow the same curved trajectory as the outer primaries to my eye) - that was the point I was responding to.
I agree it’s at the longer end of the spectrum but don’t agree it’s ‘anomolous’
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dantheman
Bah humbug
Here's an alternative image -
On my screen I measured it as 35mm and 29 mm for the two sections - giving a ratio of 35/29 or 82.86%
As Andrew says, this is possibly conservative (it could be more due to slight curvature ).
Also a link to an image showing primaries curving back slightly in towards the centre of the bird (also compare/measure the two sides of the bird!)
https://www.alamy.com/willow-warble...ithness-scotland-uk-april-image263197638.html
On my screen I measured it as 35mm and 29 mm for the two sections - giving a ratio of 35/29 or 82.86%
As Andrew says, this is possibly conservative (it could be more due to slight curvature ).
Also a link to an image showing primaries curving back slightly in towards the centre of the bird (also compare/measure the two sides of the bird!)
https://www.alamy.com/willow-warble...ithness-scotland-uk-april-image263197638.html
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Deb Burhinus
Used to be well known! 😎
Note the position of the tip of the longest tertial on this link, it looks to be the on the same vertical plane as the tip of the longest primary so position of the wing tip in relation to the tip of the longest tertial could be a constant but we can’t necessarily see the tip of the longest tertial either on this basis - I don’t see why one could suppose one over the other proposition of wing position on such views as we have in the OP.
I agree, it can not be exact science - from side view, one can only take an estimate but one can’t also wilfully ‘imagine’ the wing position to fit the maths especially when everything else points to a Chiffchaff race. I still can’t see the PP being almost the same length as the tertial length regardless, which is what I am disputing here. (There’s also sexual dimorphism in wing length btw)
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Grahame Walbridge
Well-known member
Brian, length of P1 is not a differentiating character (much overlap) but actually averages slightly shorter in Willow (+PC 1-8) as opposed to CC (+PC 4-9) but in this instance the tip of P1 is very likely hidden from view.
Ascertaining wing formula and pp is tricky due to the angle. You can see the emarginations to P3, 4, 5 but I am not convinced either way you can confirm the presence/or not of an emargination to P6. Likewise, its difficult to measure pp. However, note relative position of P2 which appears roughly level with P7, more indicative of CC, which is what it is IMHO, a fairly standard individual.
Grahame
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