The Orphean Warbler on Scilly in October 2017
An Orphean Warbler sp. was found on St Agnes late in the day on 12 October 2017. Next day several hundred birders including us had to work hard to gain views. This required long waits and, as far as we are aware, no one enjoyed close views. Neither are we aware of killer or even good photographs, with photographers doing well to gain images at all.
Slowly but surely birders had views that satisfied them and the numbers looking for the Orphean dwindled to a handful of us. In the last hour before returning to St Mary’s the small remaining group loosely discussed what we had seen and looked at BOC shots. A few shots showed the outermost tail feather (R6) as apparently largely white, favouring Western. There was discussion about the presence of dark centres to undertail-coverts, favouring Eastern, which we were certain that we had seen, several times, on perhaps the 3 longest pairs. However, the few poor-quality BOC photos that we reviewed on the spot barely reproduced these markings. The warbler was reported as ‘probable Western Orphean’ at about 4 pm and later as ‘Western Orphean’, which surprised us given what we considered was an unresolved issue of the pattern on the undertail-coverts (Eastern) and apparent pattern of the outer rectrices (Western).
Since then circumstances have been such that we have barely met up. In several telephone conservations, though, we both agreed that the warbler remained Orphean sp. in our notes until the issue with the undertail-coverts was cleared up, but the lack of photos showing the undertail-coverts meant maybe never. We reiterated this point when asked about the bird. Then yesterday Ash was speaking to an October regular who mentioned a photo on the web by Adrian Webb that showed the undertail-coverts and Ash quickly downloaded a copy (below) and it showed the longest 3 pairs of undertail-coverts with dark centres, as we saw in the field. This seems completely at odds with ID as Western (though some Westerns can show dark centres to the longest pair). We intend to send the photos for an opinion to Lars Svensson who authored the Eastern / Western split in BBOC in 2012 (volume 132, pp. 75-83).
We would leave it at that if it were not for the fact that the Orphean may still be on St Agnes –reported 2 days ago –and gettable, and that there might be more to the outer-tail pattern than previously thought, raising again the question of Eastern.
After seeing Adrian’s shots, Ash went back to Jim Almond’s photos and it struck him that there may be a ghosting of the Eastern pattern in the grey in the white of the outer rectrices. So, Ash made up the following compendium of shots from Jim’s photos, annotated them accordingly, and placed them alongside photos of adult Eastern tails from Lars’ article. We then discussed this by phone and agreed that ghosting was apparent, it was like the Eastern pattern, and crucially it was apparent on more than one photograph and on both sides of the tail, making the idea of ghosting more credible. In essence, Western typically has a pattern like Richard’s Pipit (long white wedge running up the of shaft of the inner web), while Eastern has a pattern like Blyth’s Pipit (wide short white wedge).
The underside of R6 on the closed tail (Adrian’s photo) apparently does not show the Eastern pattern. The upperside of R6 on the open tail (Jim’s photos) shows the Eastern pattern, but not the Western pattern. A plausible explanation is that light passes through R6 in the spread tail and reveals the greyish markings, but obviously does not in the closed tail. Further, it is important to remember that the markings in R6 under discussion are greyish and relatively weak compared, for example, to the denser dark-grey on R5. The markings on R6 are relatively subtle (see Lars’ photos).
In the circumstances photographers did exceptionally well to secure any photographs that permit discussion of the diagnostic features, but nevertheless we have to recognise that they are of poor quality compared to information-loaded images that we now come to expect. So, we mention the above points with this caveat. To be sure, we are not saying that the bird is an Eastern, but are pointing to evidence that will have to be assessed by BBRC and, as it stands, Eastern has not been eliminated to our satisfaction. We think that birders should have a look for themselves and make up their own minds.
Ashley Fisher & Bob Flood
22 October 2017
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