Iduna Warbler, Jersey (1 Viewer)

[andyb39]

Perhaps I was also hasty in ruling out Sykes's. I felt, having looked at the first set of images, that general upper part coloration looked better for EOW, as did the dark base colour of the primaries (fringes are pale) and the apparently dark tail. I also felt that the bill looked too long and strong for Sykes's but acknowledge that there is overlap and that the images I was basing that conclusion on show the bird craning upwards, exaggerating the bill size. The second set of images give a slightly different impression, however. It doesn't help that it's a very tatty bird.

As far as I can tell, both species can have a pale panel on the secondaries, although it's apparently more prominent on EOW. Pale fringes to the primaries are more of an EOW feature, I think. I'm not aware of significant differences in P1 length or lower mandible markings. Roland makes an interesting point about where the emarginations fall but going into that level of detail goes above my head somewhat.

 

[DMW]

I've been sent some additional images, in case anybody would like to comment further!

 

[Martin Cade]

Grahame W drew my attention to this bird and asked for some comments. As far as I can see from the images provided here this is an Eastern Olivaceous W: the weirdly patchy moult would be OK for EOW now (about 30% of them begin moulting in NE Africa in October and then suspend before they resume migration to wintering grounds in E Africa) and the newly moulted feathers visible in these images are fine for EOW but surely far too blackish for a Syke's. You do need to be a wee bit careful with eliminating Upcher's: they're sometimes closer in size (at least in the hand) to EOW than you might imagine and have many plumage similarities to these partly moulted EOWs although off course they should usually look eg much bigger billed. Attached a few photos of partly-moulted EOWs, two of them with an Upcher's for comparison - these are all from Kenya in late November/early December when they've suspended moult. I've only seen Syke's in late winter and mid-summer so their appearance in autumn is outside my experience but I'm not aware that their newly moulted feathers could ever be as dark as we're seeing in this Jersey bird.

 

[DMW]

Grahame W drew my attention to this bird and asked for some comments. As far as I can see from the images provided here this is an Eastern Olivaceous W: the weirdly patchy moult would be OK for EOW now (about 30% of them begin moulting in NE Africa in October and then suspend before they resume migration to wintering grounds in E Africa) and the newly moulted feathers visible in these images are fine for EOW but surely far too blackish for a Syke's. You do need to be a wee bit careful with eliminating Upcher's: they're sometimes closer in size (at least in the hand) to EOW than you might imagine and have many plumage similarities to these partly moulted EOWs although off course they should usually look eg much bigger billed. Attached a few photos of partly-moulted EOWs, two of them with an Upcher's for comparison - these are all from Kenya in late November/early December when they've suspended moult. I've only seen Syke's in late winter and mid-summer so their appearance in autumn is outside my experience but I'm not aware that their newly moulted feathers could ever be as dark as we're seeing in this Jersey bird.

Thanks very much indeed Martin, and Grahame, who has corresponded via private message, for this; and to everybody else who has commented.

Sometimes you just have to admit that a bird is above your pay-grade, and this one definitely is for me!

 

[CARERY]

I appreciate that this bird possibly isn't IDable with 100% certainty. But for the sake of arguments, I did manage to find a (not very good) picture of a Sykes's end of September in India in a very similar state of moult, where the newly grown feathers look surprisingly dark:
Sykes's Warbler Macaulay Library ML359756701

Of course not insisting it has to be a Sykes's though...

 

[andyb39]

I appreciate that this bird possibly isn't IDable with 100% certainty. But for the sake of arguments, I did manage to find a (not very good) picture of a Sykes's end of September in India in a very similar state of moult, where the newly grown feathers look surprisingly dark:
Sykes's Warbler Macaulay Library ML359756701

Of course not insisting it has to be a Sykes's though...

Assuming the bird in the image has been correctly identified!

 

[CARERY]

Assuming the bird in the image has been correctly identified!

Are suggesting it could be an EOW which should not occur in India?

 

[andyb39]

Are suggesting it could be an EOW which should not occur in India?

No, I'm saying I'm not sure it isn't Booted.

 

[DMW]

It's difficult to judge plumage tones in harsh sunlight but to my eyes the exposed primary in the Indian bird is not as contrastingly dark as the Jersey bird. Again, hard to tell as the image isn't sharp, but does the bill look rather weak for rama?

 

[CARERY]

Here is a link to the checklist with more photos of the same bird including a voice recording (scroll down):
https://ebird.org/india/checklist/S60167109

Again, I'm not doubting the ID of the Jersey bird but find it interesting to see that those Asian Idunas can moult at this time of the year and that the newly moulted feathers look considerable darker. Even if maybe not that dark...

 

[andyb39]

Here is a link to the checklist with more photos of the same bird including a voice recording (scroll down):
https://ebird.org/india/checklist/S60167109

Again, I'm not doubting the ID of the Jersey bird but find it interesting to see that those Asian Idunas can moult at this time of the year and that the newly moulted feathers look considerable darker. Even if maybe not that dark...

About 10 birds were observed, so some of the other images may show different individuals. I'm not saying it isn't Sykes's, more that I'm not sure which species it is. One or two of the other images do look like Sykes's. I have seen images of Booted with a similar moult pattern to this, but it could be common to both species.

As for the rattling call, Booted does make a similar call. The alarm call of Sykes's sounds impossibly dry and mechanical, but they may make similar calls to the ones in the recording. They all sound similar to me, but I don't have a good ear for calls.