Flight Identification of European Raptors Steen Christensen, Bent Pars Nielsen, R

Flight identification of European raptors Steen Christensen, Bent Pars Nielsen, R. F. Porter and Ian Willis PART 4. HARRIERS We now turn to the four harriers Circus, a genus associated with exten sive reedbeds, cornfields and moorland, not requiring trees or cliffs as do most raptors. Three—Marsh C. aeruginosas, Hen C. cyanms and Montagu's C. pjgargus—are comparatively common, but the Pallid C. macrourus is much rarer (mainly east Europe). All invariably soar and normally glide with wings raised in a shallow V, and this and their long wings and tail distinguish them from other birds of prey. The only other similar-sized raptors to soar on raised wings are the buzzards, particularly Buteo buteo (part 1), but they have short tails more fully spread and glide on flat wings. Male harriers are not difficult to identify with reasonable views, but the females and immatures of Hen, Montagu's and Pallid must often be grouped as 'ringtails' unless the head and neck pattern is seen. Fig. 3 5 below shows the head-on profiles. Figs. 36A-36D on page 234 compare the four males, and 36E-36F the heads of the three 'ringtail' females; the facing text on page Z35 comments on the main features, and outlines the areas of Europe, the Middle East and north Africa in which each species may be seen. Figs. 37-44 on pages 237-247, supported by plates 41-44, illustrate the under- and uppersides in various plumages. See also the definitions on page 53 of part 3. A B Fig. 35, Head-on profiles of harriers: (A) typical soaring and gliding with wings in shallow V; all species, though particularly the Hen Harrier Circus cyatiem, occa sionally hold the wings flat (B) or very occasionally even bowed (c), but only when gliding, never when soaring 233 A B C D E F G Fig. 36. Typical undersides of male harriers and heads of three 'ringtail' females Flight identification of European raptors 235 A. Marsh Harrier Circus aeruginosas (pages 236-238, plates 41a, b). OLD MALE WITH EXTREME PALE UNDERWINGS SHOWN. Largest harrier, with rather broad body, long and fairly broad wings, and moderately long tail. Male rufous-brown below, with paler head, grey tail and white to pale grey underwings except for black ends to primaries and brownish-buff, occasionally whitish coverts (for upperparts see page 238); female and immatures entirely chocolate-brown, but often (especially adult female) with yellowish crown, throat and leading edge to wings. Flies with rather heavy wing beats. Fairly widespread in large reed-marshes in Europe, north-west Africa and Middle East, but absent Iceland, Ireland and all except south Fenno- Scandia (where local) and nearly extinct Britain; those from north-east and central Europe move south September-April and some migrate to tropical Africa B. Hen Harrier Circus cyaneus (pages 239-241, plates 41c, 42a, 43a, 44a, b). ADULT MALE SHOWN. Shape similar to Marsh, but less bulky and with narrower wings. Male easily identified by white underparts with mid-grey wash on head and upper breast, all black primaries and dark trailing edge to underwings, also upperparts clear grey with black primaries and white rump; slightly larger female streaked brown with bars on primaries, secondaries and tail, and white rump (see also 36G). Breeds widely in moorland, large fields and open marshes in north and central Europe south to north Iberia, north Italy and Caucasus, but not Iceland, most of Iberia and Italy nor Balkans, and in Britain largely confined to Scotland, including Orkney and Hebrides; northern populations move south October-April when fairly common in marshland over much of central and south Europe and Turkey C. Montagu's Harrier Circuspygargus (pages 242-244, plates 42c, 43c, 44c). ADULT MALE SHOWN. Smaller than Hen with slimmer body, narrower wings and more buoyant flight; male slightly larger than male Pallid. Male dirtier-looking than Hen or Pallid with dark grey upperparts, head and upper breast, rusty streaks on flanks and underparts, black primaries, ill-defined dark bands on undersecondaries and narrow black bar on upperwing; female similar in plumage to female Hen (but see 36F); both sexes have melanistic form (pages 242-244). Summer visitor to open marshland, moors, heaths and cornfields in Europe and north-west Morocco, but absent Iceland, much of Fenno-Scandia (except south Sweden and Denmark), most of Italy and Balkans, irregular Scotland and Ireland, and now very few England and Wales; migrants most regular south Europe, north Africa and Middle East in May and late August-early September D. Pallid Harrier Circus macrourus (pages 245-247, plates 42b, 43b). ADULT MALE SHOWN. Male slightly smaller than male Montagu's with slimmer body, narrower wings and lighter, more agile, almost tern-like flight which, together with pale grey upperparts, white underparts and narrow wedges of black at wing-tips, recalls Common Gull Icarus canus; female similar in size, shape and plumage to female Montagu's and virtually impossible to distinguish unless whitish collar visible (see 36E). Summer visitor to steppes and plains in central and south Russia south to Caucasus, west to Romanian Dobruja, and has extended erratically to Sweden (Gotland and Oland) and Germany; migrants most regular east Balkans, Turkey and Middle East in April and September-early October (thus earlier in spring and later in autumn than Montagu's), while a few winter south-east Europe and Italy E. F, and G. Typical head patterns of female Pallid (whitish collar behind black crescent on ear-coverts and well-defined eye-stripe), Montagu's (pale side to head apart from dark crescent on ear-coverts and faint black line through eye, but no collar) and Hen (streaked and rather owl-like without distinctive pattern, having only slightly darker crescent on ear-coverts and hardly noticeable pale collar bordered by ruff of dark streaks extending to breast) 236 European raptors: Marsh Harrier Marsh Harriet Circus aeruginosus (pages 236-238, plates 41a, b) Silhouette Largest harrier, about size of Buzzard Buteo butto (part i), but with slimmer head and body, longer and more parallel-edged wings, longer tail and long legs. In head-on profile when soaring or gliding, wings raised in distinctive shallow V (3 5 A), Flight When soaring or gliding, wings are invariably raised. Active flight is series of five to ten rather heavy wing-beats followed by a glide. Typically low over ground or reed bed, but in spring performs aerial displays over breeding area. Identification Readily distinguished from other harriers by larger size and plumage pattern. Old male with entirely pale underwings (3 6A) may superficially resemble males of other species, but always has dark body below and dark back and wing-coverts above (3 8A), whereas these areas are basically white and pale grey in the other three. Female or immature with varying amounts of pale (usually yellowish) on crown, throat and forewing (37B, 38B, plate 41a) also easily identified, but all-dark individuals (38c)—which, however, invariably have paler bases to primaries and slightly paler, more gingery tails—are more difficult to identify (see also plate 41b): when one of these is seen at a distance or high overhead on migration, confusion can arise with dark Buzzard (part 1), dark Honey Buzzard Pernis apivorus (part 1), Black Kite Milvus migrans (part 2) and dark-phase Booted Eagle Hieraaetus pennatus (part 2). Even so, the last three species should be readily distinguished if bird is soaring or gliding, as harrier is only one to show shallow V (all the others soar and glide on flat wings). Buzzard also soars on raised wings, but prolonged view should reveal gliding on flat wings, while Marsh Harrier also has longer, less fanned tail when soaring and longer, slightly narrower wings. European raptors: Marsh Harrier 237 A B Fig. 37. Adult male and female/immature Marsh Harriers Circus aeruginosas from below. The adult male (37A) has a pale yellowish-white or greyish-white head, a huffish underbody heavily streaked with dark russet (looking evenly dark at a distance), white underwings with russet-brown coverts, darker tips to the primaries and a dark grey trailing edge, and a very pale grey tail. (Some individuals have greyish-buff underwings, but these generally appear white, particularly in strong sunlight.) The old male (?6A) has entirely whitish underwings or the coverts may be tinged buffish-pink. The adult female and immature (57B) are both mainly choco late-brown, often appearing darker on the wing-coverts and with paler bases to the primaries (which recall a very dark Buzzard Bufeo buteo when soaring), and a brown tail, often with a warm russet cast; the throat, crown and nape are usually yellowish, yellowish-buff or buff, but many individuals do not have a yellow throat, or indeed any pale pattern on the head, and these can be either adult females or immatures. The second-year male (not shown here, but see plate 41b) starts to show signs of adult plumage, such as black wing-tips, a dark trailing edge to the wings and sometimes a greyish tail 238 European raptors: Marsh Harrier A B Fig, 38. Three Marsh Harriers Circus aerugiwsus from above. The adult male (J8A) is tricoloured with dark brown back, rump and wing-coverts, black -wing-tips, and otherwise pale grey primaries, secon daries and tail (the last with obscure bars on the outer feathers), sometimes also a narrow grey leading edge to the wings. The adult female and the immature are both very variable and range from dark chocolate with a yellow crown and throat (separated by a black line through each eye) and a yellowish leading edge to the wings (3 8B) to entirely dark brown with out these yellow areas, but with a slightly paler, rust-tinted tail (38c).

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