Andrea Corso & Michele Viganò
MISC birding team
While raptor watching in the last 30 years, one of us (AC) noticed that among the usual plumage of Lesser Spotted Eagle (Aquila pomarina) there was a much paler plumage not shown or even not cited in any field guide, handbook or publication. Indeed, all birders and ornithologist know about the fulvescens plumage in Greater Spotted Eagle (Aquila clanga) as well as its many pale and intermediate plumages of the Eastern range of distribution (paler birds are commoner among eastern populations).
In fact, this rare paler variant of LSE plumage, being so little known, is often wrongly identified in the field by even the keen birder, sometimes as fulvescens or other times as juvenile Aquila heliaca or juv. adalberti. For this reason we would like now here to give a short description on it and some hints and tips for its identification.
We noted this plumage during autumn migration in Israel as well as during breeding season in Eastern Turkey (near Ardahan and Kars). Also the skins found in museums were from Eastern Turkey and the Middle East.
A pale variant of the usual plumage of Lesser Spotted Eagle, found both in juvenile (more frequently) than in immature or near adult birds ( no adult yet observed). The whole body appears visibly paler than the usual coloured birds, ranging from tawny-buff or buffy-cream or isabelline, paler on both under and upperwing and on head, being off white or creamy-white on lower belly, vent and undertail coverts. Usually the “thighs” appear darker, pale brownish, as well as most of the time there is a noticeable dark streaked breast band as in Spanish Imperial Eagle (Aquila adalberti) or in Eastern Imperial Eagle. All in all, the general appearance is very similar to that of a juvenile Spanish Imperial Eagle. Remiges and tail are like in the normal plumage, showing a regular and thick dark barring, with numerous bars; the inner primaries pale “window” could (or not) looks more obvious, again recalling more what is seen in juvenile heliaca. On the underwing, greater coverts (GC) and primary coverts (PC) are darker than the rest of the coverts, appearing as a dark band across the mid-wing; they are white-tipped. There is an obvious double pale comma at wrist. Pattern of upperwing is similar to that of underwing. In 2CY, faded birds are even much paler. Older birds (immatures) are similar to juvenile and appear much paler than equivalent plumage in typical pomarina (showing various moult stages and abrasion of course, differently from juvenile).
These pale variants could appear extremely similar to GSE fulvescens and even more to juvenile Eastern Imperial Eagle and Spanish IE. They are best told for:
- fulvescens: flatter wings during soaring and gliding, longer tail and neck/head, narrower wings and “hand” (more pointed wing-tip), typical LSE wing formula (less obvious in juvenile birds where the wing formula become is similar in both species). Plumage even paler in fulvescens, with contrast dark-pale more striking, more orangish in fresh bird (Ruddy Shelduck-like) and more pale creamy or off white-creamy in faded birds. Different flight feathers pattern, as for typical plumage, with a different dark barring. When shown (not all birds do), double pale comma distinctive of LSE.
- Imperial Eagles in juv. plumage (Spanish and Eastern): similar flight style showing to these species, both soaring and gliding being similar. Wings of the Imperials appear longer, narrower and more pointed, fingered primaries more numerous, narrower and longer, head and neck heavier, tail even longer. The pale rump-uppertail coverts patch on Imperials is wider and more conspicuous than in pale plumage LSE. Pattern of dark barring is similar but often, dark bars on the Imperials are wider and less numerous (but variable). Important characters are the darker, almost solid black, remiges in both Eastern Imperial and even more visibly in Spanish Imperial, with therefore the pale “window” on inner primaries much more striking and obvious at distance compared to pale variant LSE. Also, very hardly there is any pale comma on wrist in the Imperials (chiefly, it is extremely rare in Spanish) and there is no dark carpal patch on them (or only a hint of dark blotching to carpal area). When perched structure is of course very different, with stronger, heavier and higher bill of Imperials, oval, oblong nostril instead of small and round as in LSE, thicker, fuller and wider “thighs” on the Imperials, stronger legs and feet, bigger, heavier body held more horizontally (LSE appearing often more upright) and so on.
All in all, this plumage is not shown or discussed in most (or all) field guides, so it deserves great attention as indeed it poses serious ID problems when not seen well or if not bearing in mind the differences with fulvescens or even more with the juvenile Eastern Imperial Eagle and possibly more Spanish Imperial Eagle. In a “vagrant context”, when facing with outside range records of these eagles, the possibility of this paler variant pomarina should be taken into consideration.