Flight identification of European raptors

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 extensive 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, occasionally 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 2 35 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 chocolate-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 C 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, secondaries 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 without these yellow areas, but with a slightly paler, rust-tinted tail (38c). The latter type resembles a Black Kite Milvus migrans (part 2), particularly if it shows a lighter area on the lesser coverts or along the edge of the greater coverts

European raptors: Hen Harrier 239 Hen Harrier Circus cjaneus (pages 239-241, plates 41c, 42a, 43a, 44a, b) Silhouette Smaller, slimmer and narrower-winged than Marsh (compare 36A and 36B on page 234), but larger and broader-winged than Montagu's and Pallid (compare with 36c and 36D) and thus appearing shorter-winged than either species, In head-on profile when soaring wings invariably raised in shallow V (35A); but when gliding, this species shows greater tendency than other harriers to flat wings (3 5 B) or, very occasionally, even slightly bowed (35 c). Flight When soaring, wings raised. When gliding, wings usually raised, but occasionally flat or even bowed. Active flight similar to Marsh, but wing-beats faster and interspersed glides generally shorter. Identification Male readily distinguished by white underparts with grey throat and upper breast, extensive black on primaries and dark trailing edge to wings (39A, plates 42a, 43a) and wholly pale grey upperparts with solid black primaries and white rump (40A). Montagu's (pages 242-244) is rather darker-looking, whereas Pallid (pages 245-247) is even paler than Hen and has far less extensive black on primaries and no dark trailing edge to underwings; also, both Montagu's and Pallid are noticeably smaller and slimmer, while the rather broad wings of Hen give it a shorter-winged appearance. Females (39B, 40B), which are larger than males, are more difficult to identify: although larger and broader-winged than female Montagu's and Pallid, this is a subtle point only useful when observer is familiar with Hen and at least one of the other two. Generally larger white rump is no real guide, as that of Montagu's, particularly immatures, can occasionally appear larger. Head pattern should help on a close view, female Hen having far less distinct a pattern than either Montagu's or Pallid (compare 36G with 36E and 36F, see also plate 44a): the rather owl-like face is streaked brownish-buff, with a slightly darker crescent on the ear-coverts which is separated by a very narrow (often hardly noticeable) pale collar from a ruff of dark streaks extending to the breast (see also pages 242 and 245).

240 European raptors: Hen Harrier A B Fig. 39. Adult male and female Hen Harriers Circus cyaneusfrom below. The adult male (39A) is white with a fairly well-defined grey throat and upper breast, solid black primaries, a dark grey trailing edge to the wings (conspicuous at moderate ranges), and a pale off-white and unbarred tail; when seen overhead in strong sunlight, the translucent white secondaries can give the effect of a tricoloured wing (plate 42a), The adult female (39B) is very similar to the females of both Montagu's and Pallid, with a ground colour of buff-brown, finely streaked on the under parts and underwing with blackish-brown, broad brown barring on the primaries and secondaries, and three bands on the tail; the head markings lack the more contrasted patterns of Montagu's and, particularly, Pallid (cf. 41B, 41c, 43c, 43D and 36B-G). The immature (not shown) is very similar to the adult female: we know no way of separating them except by the paler edges to the upperwing-coverts and those are visible only at the closest ranges

European raptors: Hen Harrier 241 A B Fig. 40. Adult male and female Hen Harriers Circus cyaneus from above. The adult male (40A) is entirely grey, even slightly bluish-grey, apart from black primaries, a very faint and sometimes barely discernible darker trailing edge to the wings, and a clear white rump patch; it is the only male harrier with such a rump patch (cf. 38A, 42A, 44A). The adult female (40B) has dark brown back and wings (with a slight golden-buff tinge to the median coverts, noticeable only in good light), a white rump (typically larger than those of female Montagu's and Pallid) and a grey to grey-brown tail with broad bands of dark brown; the head pattern lacks the contrast of female Montagu's and Pallid, but this feature is useful only at close range (see also 36G and 39B with discussion on page 239). Immatures are virtually indistinguishable from the adult female (but see caption to fig. 39)

242 European raptors: Montagu's Harrier Montagu's Harrier Circuspygargus (pages 242-244, plates 42c, 43c, 44c) Silhouette Male noticeably slimmer and narrower-winged than male Hen (compare 3 6B and 36c on page 234): as a result wings appear longer and, at a distance or high overhead, shape and structure not unlike long-tailed falcon, such as Kestrel Falco tinnunculus (part 8). Size corresponds to Pallid (compare with 36D), although males of that species are often slightly smaller. Female appears a little larger than male, though size difference is, in fact, very small. In head-on profile when soaring or gliding, wings raised in shallow V (3 5 A). Flight When soaring or gliding, wings raised. Active flight is very light and buoyant, usually five or six rather leisurely wing-beats followed by a wavering glide. Generally low over ground, but often soars high in breeding season, when V of wings becomes accentuated. Like other harriers, will suddenly check in flight and turn agilely to pounce down to ground after prey. Identification Male smaller than Hen (pages 239-241), but slightly larger than Pallid (pages 245-247). Readily distinguished from both by darker, less precisely patterned appearance with streaks on flanks and dark lines on underwings (41A, plate 42c) and darker grey upperparts with narrow black bar on each upperwing (42A, plate 43 c), all features lacking in the whiter and cleaner-looking Hen and Pallid. Female (41B, 41c, 42c) smaller and narrower-winged than female Hen (see page 239) and very similar in size to Pallid, with similar extent of white on rump; although sometimes claimed otherwise, underwing pattern is of limited use in separating Montagu's and Pallid because both can show either barred or dark brown secondaries, though immature Pallid does have paler, more buff underwing-coverts and body. Only reliable character appears to be head-pattern (compare 36F with 36E and 36G, see also plate 44c): female and immature Montagu's both have whitish sides to the head bordered behind by a dark crescent on the ear-coverts and with a faint black line through the eye, whereas Pallid also has a whitish collar behind the ear-coverts and a welldefined eye-stripe (see also pages 239 and 245). Rare melanistic form (4ID, 42B) easily identified, but needs to be distinguished from alldark female or immature Marsh (38c) which is, however, larger and broader-winged. Pig. 41 (opposite). Adult male, two adult female, melanistic female and immature Montagu's Harriets Circus pygargus from below. The adult male (41 A) has a basically white underbody, with a dark grey chin, throat and breast, and rusty streaks on the flanks; the black primaries merge into the whitish secondaries which show one or two black bars and a greyish trailing edge, while the wing-coverts are flecked and barred with blackish; the pale grey tail is lightly barred. The adult female is

European raptors: Montagu's Harrier 243 A B C D E similar in colour to the female Hen Harrier (39B), but the secondaries may be either barred (41B) or dark brownish contrasting with the rest of the wing (41c). The immature (41E) resembles the female, but has an unstreaked, warm chestnut underbody and underwing-coverts; as in the female, the colour of the secondaries varies from dark, as here, to barred. Both sexes have a rare melanistic form: the male (not shown) is black or blackish-brown below and slightly greyer above; the female (41D) is entirely dark chocolate-brown except for the banded tail and greyish-white bases to the primaries which help to give the appearance of a small, slim-winged, light-flying female Marsh Harrier (cf. 37s)

244 European raptors: Montagu's Harrier A B C D Fig. 42. Adult male, melanistic female, adult female and immature Montagu's Harriets Circus pygargus from above. The adult male (42A) is pale bluish-grey (somewhat darker grey on the crown and wing-coverts), with blackish primaries, a narrow black bar along the centre of each wing, often a pale grey panel on the inner primaries and outer secondaries, and slight barring on the outer tail. The melanistic female (42B) is entirely dark chocolate (blackish-grey in the male) apart from the banded tail. The adult female (42c) is mid-brown with slightly paler, more buffish [continued on page 245]

European raptors: Pallid Harrier Pallid Harrier Circus macrourus (pages 245-247, plates 42b, 43 b) Silhouette Male slimmer and more lightly built than male Montagu's (compare 36c and 36D on page 234) and noticeably slimmer and narrower-winged than male Hen (compare with 3 6B). Female larger than male and virtually identical in size and shape with female Montagu's. In head-on profile when soaring or gliding, wings raised in shallow V (35A). Flight When soaring or gliding, wings raised. Active flight, particularly of male, is even lighter and more buoyant than Montagu's, the male at times appearing almost tern-like, with agile changes of direction. Identification Slim build, narrow wings with only thin wedges of black on primaries, and very pale plumage with white underparts (43 A) and light grey upperparts (44A) give male something of appearance of Common Gull Larus canus and make it readily distinguishable from all other male harriers (see also plates 42b, 43b). Female (43c, 43D, 44B) and immature (43 B, 44c) difficult to distinguish from corresponding plumages of Hen (pages 239-241) and Montagu's (pages 242-244). All three are buff streaked with brown and have bars on primaries, secondaries and tail, and a white rump (size of rump patch is of doubtful value in identification, though generally those of Pallid and Montagu's are smaller than that of Hen); despite claims to the contrary, colour and pattern of secondaries are of little use in separating female or immature Pallid and Montagu's, since both species can have these either barred or dark (appearing brownish-grey), though the contrast between dark secondaries and the otherwise pale underparts of the immatures is greatest in the Pallid. Pallid and Montagu's are smaller and narrower-winged than Hen, but this is useful only if observer familiar with Hen and at least one of the other two. The one reliable feature appears to be head pattern (compare 36E with 36F and 36G): female and immature Pallid have whitish cheeks with a dark line through the eye and a blackish crescent on the ear-coverts bordered by a whitish collar (the definition of this pattern varies to some extent, but in well-marked individuals it is useful even at a distance); Montagu's has no whitish collar and, while some Hen show a faint one, they lack the eye-stripe and blackish crescent on the ear-coverts (see also pages 239 and 242). M5 [Montagu's Harrier: continued from page 244] wing-coverts, a white rump (varying individually in size and conspicuousness) and a grey to grey-brown tail with bands of dark brown; the head pattern includes a dark crescent on the ear-coverts, but only a faint black line through the eye and no whitish collar (see also J6F, 41B and 41c with discussion on page 242). The immature (42D) is similar to the female, but often has darker back and wings which make the rump patch more prominent

246 European raptors: Pallid Harrier Fig. 45. Adult male, immature and two adult female Pallid Harriers Circus macrourus from below. The adult male (43A) is entirely white apart from black middle primaries forming narrow wedges, barely discernible greyish bars on the tail and sometimes a very faint grey wash on the chin and throat. The juvenile (45B) is very similar to the young Montagu's Harrier, having pale chestnut-buff underparts and underwingcoverts, similarly barred primaries and tail, and secondaries which can be either [continued at the foot of page 247]

European raptors: Pallid Harrier 247 A B C Fig. 44. Adult male, adult female and immature Pallid Harriers Circus macrourus from above. The adult male (44A) is a soft pale grey with only narrow black wedges on the primaries and slightly darker barring on the outer tail, but no white rump. The adult female (44B) has dark brown back and wings (with paler, more golden-buff coverts, noticeable only in good light), a narrow white rump, and a grey to greybrown tail with bands of dark brown; the contrasted head pattern includes a whitish collar behind a dark crescent on the ear-coverts and a well-defined dark line through each eye (see also 36E and 43c with discussion on page 245). The immature (44c) is very similar to the adult female, even showing the distinctive head pattern with whitish collar and dark crescent, but usually has darker brown back and wings [continued from page 246] barred or, as here, dark blackish-brown contrasting with the rest of the wing; the underparts frequently appear paler than those of the immature Montagu's, however, and the head pattern shows a more prominent eye-stripe and a whitish collar behind the black crescent on the ear-coverts. The adult female is similar to the immature, and the secondaries can vary from dark (43c) to barred (43D), but the buffish underparts are finely streaked with brown; the head pattern again includes a more prominent eye-stripe and a whitish collar which is probably the most reliable feature for distinguishing from Montagu's (cf. 41B, 41c and 36E-G)

PLATE 41. Above, Marsh Harriers Circus aeruginosas {photos: Eric Hosking): note long broad wings, held in shallow V in soaring and gliding, and long tail (pages 236-238), J.eft, female/immature, Pakistan, December: chocolate-brown with yellowish crown, chin and throat. Right, immature male, Suffolk, April: all brown apart from black ends to primaries, dark trailing edge to wings and paler, gingery tail. Below, male Hen Harrier C. cyaneus attacking photographer near nest, France, June {photo: Pierre Petit): all light grey above, with black primaries (pages 239-241)

PLATES 42 and 43. Adult male 'grey' harriers. Top two, Hen Harrier Circus cyaneus, France, June {photos: Pierre Petit)-: white below with grey head, black primaries, dark trailing edge to translucent secondaries (pages 239-241). Lower left on each plate, Pallid C. macrourus, Sweden, June (photos: Erik Engqvist): slim build, all white below but for narrow black wedge on primaries (pages 245-247). Lower right on each, Montagu's C. pygargus: from beneath, Spain, April (photo: R. C. Homes) with dark grey head, rusty streaks on white lower breast, black primaries, black bars on secondaries, patchy flecking on white coverts, lightly barred tail; from above, Sweden, May (photo: Karl-Erik Frid^en) showing mid-grey upperparts, black primaries, narrow black bar bordering coverts, wings in shallow V (pages 242-244)

P L A r E 44- Above left, adult female Hen Harrier Circus cyaneus, Norway {photo: Gunnar Frydenlund); above right, the mate of the male shown upon plates 42a and 43 a, France, }\me(photo: Pierre Petit). Note long and fairly broad wings, somewhat owl-like head bordered by a 'ruff' of streaks extending on to underpays, and bars on primaries, secondaries and tail (pages 239-241). Left, adult female Montagu's Harrier C. pygargus, Norfolk, June {photo: Eric Hosking): buff with brown streaks, and broad bars on secondaries and tail, white cheek and eyepatch bordered by crescent of black, but lacking white edging collar of a female Pallid (pages 242-244, also 36E-36F on page 234)