It is indeed a very nice analysis by Tib78 and (skbirder) you are a better birder than me to identify this by head pattern and structure. The structure of the tail tip/wing tip/tertial tip ratio is better for Isabelline, as on Northern the wing tip lies closer to the tail tip.
In the instance of these photos I feel that the median and greater coverts are a little dark (and perhaps darker than the 'go to' impression of Isabelline) but no darker than on a couple of the photos here, for example - http://www.kuwaitbirds.org/birds/isabelline-wheatear - indeed overall exposure issues on the photos could also explain their darkness.
Likewise, I would not use the rump shade as an argument either way due to poor exposure - https://www.hbw.com/ibc/photo/isabelline-wheatear-oenanthe-isabellina/adult-bird-1
I still don't see the rump/tail pattern of a Northern Wheatear on the rear view either - here a N Wheatear - http://www.gobirding.eu/Images/Pass...ear/Wheatear, Penninis, 3-Oct-07 (AB24) L.JPG
I guess also what I see is a lack of any gingery warmth to the g covert edges as I would expect on Northern; the edges to the coverts, secondaries and tertials are creamy white; the blacks of the remiges and rectrices are not jet-black but washed out black.
Over the years, I have seen several Isabelline Wheatears look like this, so I will go by my experience, but it may well be that we will ultimately differ in our opinions - they can be tough.
B
Does anyone have any pics of a nailed on Issy showing these leg scales? It would be useful to know just how useful this feature is.
I too fail to perceive this as a Northern Wheatear, particularly since they are now as fresh as they come, sporting both the rich tone of the pale edges of the coverts, and the very dark central parts of the same feathers.
As a matter of fact, I cannot even perceive the base colour of the remiges as 'washed out black', but see it merely as dark brown, in sync with Isabelline.
Had the photo been taken during spring, I might have been inclined to lean more towards a sun bleached Northern W., but this immaculate bird looks like a typical Isabelline for me.
Peter
PS the sentiment that the alula isn't black enough for I.W. is not the strongest of arguments, since the photo angle doesn't allow us to see more than a very dark line at the edge of the wrist, and that thin line is - in my eyes - pretty black....
Peter,
Regarding the alula: it is black, it always is, whether you are looking at a Northern or an Isabelline. The interest of the alula for ID purposes is to compare it to the center of the greater coverts as I alluded in my previous comment. On the last picture, my interpretation is that the alula and most of the greater coverts are correctly exposed and not in the shadow, and I can’t detect a real difference in shade between the alula and the center of the greater coverts. If correct, this is a very strong pointer to Northern. Still the bird is not quite in a perfect position to assess this with a high level of confidence.
And I can only agree with you and Brian on the fact that this bird lacks the richer tones that one usually expect on a typical Northern, but pale Northern do exist. In fact, while looking m again at these images yesterday, my opinion was slowly starting to change and shift towards Isabelline because of the paleness of plumage and the wing length...the bird looks also long legged and has a very upward stance (the last feature is often seriously overrated in my opinion though!).
But then I kept comic back to those dark coverts and rather narrow fringes to all feathers group. I didn’t know before this discussion but basically, fresh Isabelline has broader pale fringes to all feathers group (primaries, secondaries, coverts including the primary coverts. For instance on almost any pics of fresh plumaged Isabelline in September; it is almost impossible to see the center of the greater coverts because they are covered by the pale fringe of the adjacent feathers.
Ultimately, while trawling through the Isabelline wheatear gallery of the IBC, I found a bird that is, in my view, extremely similar (but more worn) to the OP bird in terms of colour, head pattern and general impression...but it is clearly a misidentified Northern: https://www.hbw.com/sites/default/f...c/ibc/p/2014-10-12_09.41.22.jpg?itok=5F7kFYTN
I thought that the dark scaling on the thigh was a ‘silver bullet’ feature for northern - and a quick browse online suggests that if Isabelline can show these scales, they do so at least pretty infrequently. Does anyone have any pics of a nailed on Issy showing these leg scales? It would be useful to know just how useful this feature is.
no, it's a northern. issy is white in front of the eye not behind. and it doesn't show these contrastingly dark centered median coverts.
Agree with Lou - Northern for me too! Just additional feature for northern is the neck, which is not enough powerful and tall and the head is definitively very small for Isabelline. Just the legs are confusing me a bit because they appear a bit taller for northern and I would be happy to know if a hybrid could be possible?
Pavel, these mentioned features aren't really reliable cause they are solely dependent on the degree of 'raised feathers', we might call it, and/or the position the bird is in when photographed. And a lot of other things...
A bird in an upright position, with the feathers slick to the neck/skull/body will look small-headed, whereas a bird with the head resting on the shoulders, and all 'fluffed up' will look big-headed.
All the different stages in between these two extremes are possible for any individual of each species to attain in a fraction of a second.
A moving object that you cannot possibly compare to another moving object, or make any conclusions from.
As a taxidermist I have skinned and measured both species, and I can assure you that there's no tangible difference in the width of the neck between the two, and - although not measured - neither, I guess, is there in the size of the skull.
We have to stick to the hard facts here (and there aren't as many as one might gather from this discussion).
Another highly dubious field mark is the mentioned difference in the size and structure of the bill.
As there's more overlap than not regarding measurements, the only thing you might conclude is that the size of the bill is visually comparable only if two individuals of the said species were photographed in the exact same position (i.e. not one sleek bird, and one moribund/fluffed up to the utmost), and even then the chances are that the one considered to be the smaller-billed individual of the two, might well belong to the species claimed to sport the largest bill.
And if we start to bring the large leucorrhoa-subspecies of N.W. into the picture, the statement of bill size of A SINGLE INDIVIDUAL of one of the two species becomes quite absurd.
It thus goes without saying that you'll (most probably) never be able to tell a hybrid between these two species (has one ever been recorded?) from an individual of either species, with the possible exception of a singing adult male in the spring/summer.
Peter
PS what I've learned from this thread is that each birder has his/her own ideas of what are 'typical' traits of this 'species-pair'.
Consequently I withdraw my hard to prove 'gut feeling impression', and am quite at piece with not putting a name to this critter.....