Myth and Legends in Birding : one typical case – the Atlas Flycatcher wing pattern
by Andrea Corso
Birding, as any human fields of knowledge, is full of false myth and misleading legends. These are usually some believing and “findings” reported by ornithologists and birders, in field guides or papers, born from some mistakes (that are indeed absolutely human and nothing too strange as …errare humanun est, but …perseverare autem diabolicum J) and repeatedly reported without real double checking again and again in all following books and papers. One of my first learning lesson from by my illuminated father is that anything need to be seen with our own eyes and to be re-tested or re-studied personally, verified always directly before having an own idea and opinion to may discuss on and to support our believing. So that what I do always on birding too.
One of that typical example, is Atlas Flycatcher (Ficedula speculigera) ! That species has been already discussed in details in Birding Frontiers by Martin and Co. but here, in this very brief note, I wish to go through the main misleading legend on speculigera – THE ALL WHITE GREATER COVERTS !!
Atlas Flycatcher (Ficedula speculigera) – variability in the wing pattern, rump, tail and half-collar. by Lorenzo Starnini.
Note that on closed wing there is an obvious and striking big white “patch” where no dark bases to the GC (greater coverts) are visible, and the outermost black GC are not well detectable, leading to the false common believing that all the GCs are white ! In the birds with open wings up to 3 outer GCs are instead visible. Note also the MC (median coverts=) with extensive white tips almost as much as in Semi-collared Flycatcher. Note that the 2nd cy male show white on retained outer tail feathers, a much restricted white on retained remiges, and patchy plumage (combination of fresh and abraded feathers). Illustrations by Lorenzo Starnini from skins and photos from Morocco and Tunisia made for the forthcoming paper in Birding World.
To deal with this, (see above) a plate by the bird artist master Lorenzo Starnini and part of the extensive and detailed text that Ottavio Janni and myself are going to publish in a forthcoming paper in BIRDING WORLD that will deal with the variability of this marvelous Flycatcher. Here a very brief version of the chapter on Greater Coverts, but in BW relevant issue you will find a 20 pages paper.
The accompanying plate is also one of the fantastic plates Lorenzo is working on for the field guide him and me are preparing “ Advanced ID of difficult WP species” which will be out on the market hopefully in 3 or 4 years and that will deal with all the latest update in ID of the most difficult WP’s species of birds, illustrating all the key identification features and chiefly all their variability (something almost never reported and shown by field guides).
1) GREATER COVERTS: the most common misconception – along with the tail pattern – concerns the pattern of the greater coverts. Mild (1993,1994) report that Atlas Flycatcher “usually have all white greater coverts”; and add that in Pied x Collared hybrids and pure Collareds “usually their outermost greater coverts are black, or all the greater coverts show at least dark bases.” The idea that Atlas Flycatchers should have entirely white greater coverts has been repeated in all subsequent publications. Etherington & Small (2003), for instance, reported that “a fundamental difference in speculigera and iberiae is that their greater coverts are normally wholly white”. They add that “rarely there is a small area of black at the base of the outer greater coverts” and finally that “some Collared may show more white on the greater coverts than Atlas, but they are never completely white”. These authors correctly pointed out that Atlas Flycatchers can have a black area at the base of the greater coverts, but in fact this area is often present and can be extensive (see below). The second edition of the leading European field guide( Svensson et al. 2009) depicts and describes Atlas Flycatcher as having “all-white greater covers”, as opposed to iberiae which shows “much white”. We examined this feature carefully and found it to be highly variable but most importantly we found that birds showing a full set of all-white greater coverts proved very hard to find. Indeed, we failed to find a single bird with all GCs entirely white, while most birds shown 2 to 3 outermost GC all black, or 1-2 black and the 3rd showing a chequered pattern (black and white). The oft-repeated claim that Atlas Flycatchers have all-white GCs is therefore misleading or even proven to be false: it is only that the GCs that are visible on the closed wing appear all-white, and particularly bright and conspicuous, having no black base like in the other species. In fact, in Collared and Pied there is always a greater number of white GCs with visible dark bases, and the latter are more conspicuous. Among Iberian Pied, we found that the number of unmarked white coverts is closest to Atlas, though lower on average (60-85% of the GCs showing white); though with the extremes quite alike. In the vast majority of Pied Flycatchers, most of the GCs with white on them also have an extensive dark base which is easily visible in the field, while Collared have on average more coverts with dark bases than Atlas (Etherington & Small, 2003), although we found a few birds with the dark area barely visible on the closed wing, thus approaching Atlas. Iberian Pied is extremely similar: often the white patch white patch itself is less conspicuous since on average more white feathers have black markings, but on the whole Iberian Flycatcher and Atlas are very much alike in this regard, making their identification more difficult than has been suggested (e.g. in Svensson et al., 2009).
NB: The exact pattern of the GCs is much easier to assess when the wing is fully open (Fig. 1). When it is closed, the unmarked, pure white median coverts overlap with the outermost GCs and conceal their pattern, leading to the impression of a full set (including G1-G2) of entirely white greater coverts (see below). Indeed, on perched birds in the field the impression of a large, conspicuous wide patch on the GCs, which has contributed to the misleading belief that all GCs are entirely white.