and the ID challenge of Western Tree Warblers
Following on from this post, seems worth exploring the subject a little further. The most likely ID of the Fuerteventura warbler seems to be of the Saharan Olivaceous Warbler. However without field notes and only photos to go on it’s a little tricky for the outside observer. I found it intriguing as I have never seen the taxon and kind of wondered what it might get called if it turned up in NW Europe? Would I know what it was?
With multiple taxa, the old Olivaceous Warbler group is tricky one to member/ get your head around. So here is a reminder of how it plays out following the split of Western and Eastern Olivaceous Warblers:
Western Olivaceous Warbler Iduna opaca (just the one taxa)
Eastern Olivaceous warbler Iduna pallida (several taxa, those in Western Palearctic region:)
Nick Watmough and Grahame Walbridge made helpful comments as well as Ricardo and Andrea HERE and Nick sent some very useful comparison shots of Western Olivaceous Warbler:
I see this bird is now on the rarebirdspain website as Saharan OW and probably with good reason. I suspect the bill structure (based judged on front on photo on RBS site) excludes Western OW – please find attached a couple of shots of Western Olivaceous Warbler taken in Morocco in May 2013 (actually no more than 50km from where we saw Saharan OW). By chance they are taken from below and show the shape of long deep-based bill quite well. To my mind Western OW is a bigger sturdier beast that either Saharan OW or my recollections of eleiaca (which I assume account for all UK records?), but as ever that is hard to judge from photos.
All the best, Nick
Grahame Walbridge commented:
“The bird does not look anywhere near strong-billed enough for opaca. Lower mandible colour also looks wrong, should be entirely yellow. Pity there are no plan views (above or below) of the bill which would nail it for me.
Put simply it doesn`t look like a Western and combination of upperpart tone and lack of wing panel eliminate elaeica. By a process of elimination it must be Saharan (reiseri), though I am very uneasy at using this method in arriving at an ID! Probably safer to say “in all likelihood its a Saharan” or, something similarly tentative (unless more info forthcoming on field appearance).”
to compare with