British VOLUME 87 NUMBER 3 MARCH 1994

Identification of jackdaws and Steve Madge Illustrated by Hilary Burn

hese four small are similar in size and all overlap in range and Thabitat to a certain extent. Separating jackdaws from choughs is only a marginal problem involving poorly seen birds, but each pair of species pre­ sents some interesting problems. This short paper reviews the identification of dauuricus and compares the two species of fyrrhocorax.

Separating the jackdaws Daurian Jackdaw is die eastern counterpart of our familiar Eurasian Jackdaw C. monedula, which it replaces to the east and southeast of Lake Baikal. Despite the striking differences between adults of die two jackdaws, they are clearly very closely related and form a species-pair. There is a good case for lumping them as one polymorphic species, but there is little evidence of hybridisation where die two forms marginally meet (in me region of Lake

{Brit. Birds 87: 99-105, March 1994] 99 100 Identification of jackdaws and choughs Baikal and in ). The difference in eye colour may be an important factor in preventing other than very occasional mixed pairings, and their nesting habits may also differ marginally. Both jackdaws are strongly migratory over large areas of their ranges and it is therefore not surprising that some vagrancy occurs. Vagrant Eurasian Jack­ daws have occurred as far east as Japan, and have crossed the Adantic to the and even the eastern seaboard of North America. Daurian Jackdaws have been recorded west to Krasnoyarsk in central , south­ west to Uzbekistan in central Asia and exceptionally in Finland and Sweden. Daurian Jackdaws have two colour phases, which may in fact be entirely age-related, although more intensive field research is required to sort this out for certain. Known vagrants have all been of pied individuals, but the black phase, which is confusingly similar to Eurasian Jackdaw, is an immature plumage stage and vagrants are perhaps much more likely to turn up in this easily overlooked plumage man as pied adults.

Fig 1. Foreparts of Eurasian Corvus monedula (left) and dark-stage (immature) Daurian Jackdaws C. dauurkus (right). Note dark irides, silver streaking on sides of head and more extensive black on throat and breast of Daurian (Hilary Burn) Piebald Daurian Jackdaws The well-known piebald phase presents a very distinctive appearance, the basic pattern of which recalls a miniature 'hooded' Carrion C. corone comix, with whitish underparts and collar contrasting with blackish head, breast, undertail-coverts, wings, upperparts and tail. With suspected vagrants, the more likely possibility of a being a partial albino Eurasian Jackdaw should be considered, but Daurian has a dark (not pale) iris and fine silver streaking on the sides of the head behind the eye. Individuals in this plumage stage are otherwise quite unmistakable and are invariably adults.

Black Daurian Jackdaws The black phase is an immature plumage stage and seems not to be exhibited by either full adults or juveniles. This confusing situation suggested to some authorities that a third species of jackdaw existed, which was named C. negkctus. Whether or not all immatures are black is unclear, as this complex ageing process has only relatively recently been clarified by Russian researchers (summarised by Jollie 1985). Basically, it seems that the short-lived juvenile plumage is piebald (recalling a dull version of the adult), but soon after fledging a moult of the head and body plumage produces the black plumage stage, which is retained throughout the winter and at least into the Identification of jackdaws and choughs 101

35. Daurian Jackdaw Gonitis dauurkus, Mongolia, June 1981 (Peter Kennerley) following summer, perhaps until the bird is in its third calendar-year. Black-phase individuals are very similar to Eurasian Jackdaw, but are more uniformly blackish, with the nape a relatively darker grey than on Eurasian Jackdaw. Like pied individuals, the iris is dark, but the area of silver streaking behind the eye is rather less extensive, though it should be visible as a lighter area under close scrutiny. A major pitfall in late summer is produced by juve­ nile Eurasian Jackdaws, which also have a dark iris and a darker-grey and less-contrasting nape than adults. The first moult (only a few weeks after fledging), however, gives an appearance virtually identical to that of adults, although the irides sometimes remain dark well into the first winter, possibly even until the first spring on some individuals. A jackdaw with a darkish nape and iris in late autumn and winter is, therefore, a good candidate for Daurian. In good light, another useful clue is given by the contrasting blacker throat and upper-breast pattern (a 'ghost' of the pattern of the pied adult stage). On Eurasian Jackdaw, the throat is blacker than the breast, whereas on Daurian the black extends onto the upper breast and forms a more extensive shield (reminiscent of 'hooded' ), which contrasts slightly with the dull blackish of the remainder of the underparts. By their first spring, Daurian Jackdaws may start to acquire pale areas on the nape; from my limited studies in the field in June in Siberia, it seems that the pale feathering first becomes apparent on the upper nape and spreads downwards, thus producing the reverse of the nape pattern of Eurasian Jackdaws (which, especially those in eastern populations, often have a narrow whitish area at the base of the nape).

36. Daurian Jackdaw Counts dauuricus, Mongolia, June 1981 (Peter Kennerky) 102 Identification of jackdaws and choughs Other differences Both jackdaws are extremely similar in behaviour, calls, size and shape. There is, however, a tendency for Daurian to have the second primary shorter than the fifth (equal on Eurasian) and for its first primary to be relatively a little shorter than on Eurasian, but these differences are not infallible. Vocally, the two arc almost identical, but some calls of Daurian seem slightly higher in pitch compared with those of Eurasian Jackdaws in Britain.

Separating the choughs The two species of chough differ from Corvus crows in having a smooth, not scaled, tarsus, very short, dense, nasal feathers and brighdy coloured bill and feet. Both inhabit open rocky and grassy habitats, chiefly in mountainous regions, although the Red-billed P. pjrrhocorax occurs widely on coastal cliffs in the west of its range. Both species arc gregarious and overlap extensively in distribution, at times occurring together on the same mountain slopes, although the Yellow-billed P. graculus has a preference for higher elevations than the Red-billed, the latter favouring grassy slopes and plateaux with grazing . Both species feed primarily on , but the Yellow- billed Chough also freely scavenges about human habitation. Parties of jackdaws will also wheel about cliff faces and distant birds can suggest choughs, but they have different calls, are relatively larger-headed and have a stouter black bill, less buoyant flight and neater, less fingered, wing tip. The two choughs are similar in size and basic shape, but in flight there are subtle differences which have been discussed by Tucker (1976) and Grant (1987), although the latter pointed out that individuals in primary moult in late summer can be very similar and doubted the proposed differences. My studies of both indicate, however, that differences are usually quite marked, particularly when the birds are directly overhead, although moulting individuals are confusing and identification is then best aided by voice. A very useful paper by Konigstedt el al. (1990) admirably tackles the subject and confirms these findings, which are discussed below.

Yellow-billed Chough The small, clear-yellow bill, often appearing whitish, is diagnostic when this crow is close. At longer ranges, however, Yellow-billed can easily be confused with Red-billed Chough, which shares its habitat, red legs and gregarious habits. Many field guides warn that there can be confusion with recendy fledged Red-billed Chough, which has a shorter and yellower bill than that of the adult, but the colour is a dull, dingy orange or fleshy-yellow, not the clear bright pale yellow of Yellow-billed, and juveniles are invariably accompanied by the much more distinctive adults. Yellow-billed, even in silhouette, has a shorter bill and relatively smaller head and longer tail than does Red-billed, the tail projecting well beyond the wing tips when at rest (only equalling the wing tips on Red-billed). The flight shape also differs, but can be difficult to judge accurately unless the birds are directly overhead, but Yellow-billed has a smaller head, less 'square' wings (owing to gradation of primary lenguhs), a more curving trailing edge to the wing and a more pinched wing base. The five-fingered primaries are less Identification of jackdaws and choughs 103

Kig. 2. Red-billed Pyrrhocorax pyrrhocorax (left) and Yellow-billed Choughs P. graculus (right) to show differences in flight silhouette. Note more projecting head, relatively shorter, squarer-tipped, tail and more rectangular wing shape, created by straighter trailing edge and longer, more even primary 'fingers', of Red-billed (Hilary Burn) prominent than those of Red-billed and are of uneven length (forming a rounded, not blunt, outline to the wing tip). The tail of Yellow-billed is relatively longer and more rounded at the tip than that of Red-billed; this can often be roughly gauged when birds are directly overhead by comparing exposed length from wing base to tail tip with width of wing base (longer on Yellow-billed, more or less equal on Red-billed). Calls are also quite diagnostic, those of Yellow-billed being mostly rather 'uncorvine': a sweet, rippling 'preeep' and a descending thin, whistled 'sweeeoo', both calls varying somewhat in pitch and intensity, the latter recalling a squeaky version of the call of Red-billed Chough. A rolling 'churrr', possibly an alarm call, is often given.

Red-billed Chough The slender, curved red bill is diagnostic. Confusion is likely only with Yellow- billed Chough in mountainous regions where the two species often occur together; but their flight silhouettes and calls also differ. Red-billed has relatively broader and markedly more rectangular wings than Yellow-billed, with six strongly-fingered primaries (the longest three of which are virtually equal and form a squared tip to the wing outline), a straight trailing edge to the secondaries (lacking gentle bulge and pinched base to the trailing edge of Yellow-billed) and a shorter, more square-ended tail (tail length more or less equal to width of the base of die wing, not markedly longer as on Yellow- billed). Red-billed has a more prominently projecting head than Yellow-billed, which is enhanced by its longer bill. At rest, die wing tips equal the tip of die tail, whereas on Yellow-billed die tail distincdy projects beyond die wing tips; diis difference can be visible at quite long ranges when birds flirt their wings when calling. Even when die bill colour is not discernible, die slender curved shape is often apparent at reasonable ranges. Distant birds on the ground may often be safely distinguished (at least from jackdaws) by die vigorous digging action as diey feed, digging and pulling at surface vegetation and turning over small stones in dieir search for invertebrates. By comparison, Yellow-billed Choughs feed by picking and digging at the ground in a less strenuous i 04 Identification of jackdaws and choughs manner. The flight action is veiy buoyant, with deep, bounding progression, the birds freely indulging in spectacular aerobatics over cliff faces. The usual call is a high-pitched, almost hoarse 'chee-aw', uttered both in flight and on the ground. (The bird's name, chough, is onomatopoeic if pronounced 'chow' rather than 'chuff.) Although this is distinctive, jackdaw vocabulary includes a similar call, but that of Red-billed Chough is clearer, more explosive and higher in pitch. Other calls are basically variants of this call, but more distinct is a harsh, scolding 'ker ker kcr', seemingly of alarm.

Summary This short paper discusses the identification of Daurian Jackdaw Camus dauurkus and reviews the field features of Yellow-billed Pyrrhoanax graculus and Red-billed Choughs P. pyrrhocmax. Black- phase Daurian Jackdaw is very similar to Eurasian Jackdaw C. monedula, but has more extensive deep black on throat and breast, silver streaking on sides of head, dark irides, and acquires whitish areas on upper nape at early stages of transition to pied adult plumage (thus giving reverse of nape pattern of Eurasian Jackdaw, which is often obviously whitish at base of neck). The choughs may be separated in flight by voice, wing shape and head and tail proportions. Yellow- billed has a small head and bill, less strongly fingered and more rounded wing tip, longer and more round-tipped tail and a slighdy curved trailing edge to the wing which is pinched at the base. Red-billed has a more projecting head (enhanced by longer bill), shorter and more square- ended tail, distinctly rectangular wings with six (not five of Yellow-billed) prominently lingered primaries and straight trailing edge to the secondaries. These differences are best judged when birds are directly overhead.

References GRANT, P.J. 1987. Wing shape of Chough and . Brit. Birds 80: 116-117. Joi.UK, M. 1985. The dimorphism of Coioeus dauurkus, the Asian Jackdaw. J. Om. 126: 303-305. KONIGSTKDT, D., LANGBKHN, H., & FRKDK, M. 1990. Zur Unterscheidung der Flugbilder von Alpenkrahe Pyrrlmorax pyrrhocorax und Alpendohie P. graculus. limkoki 4: 22-27. Tl.'CKER, V. R. 1976. Identification of Chough and Alpine Chough in flight. Brit. Birds 69: 369-370. Stem Madge, 2 Church Row, Sheoiock, Torpoint, PL] 1 3EH

Fig. 3. Choughs and jackdaws (Hilary Burn) Red-billed Chough Pyrrhocorax pyrrhocorax la adult. In flight, note rectangular wings, long-fingered primaries and square-ended tail; tail- length equals width of wing base. I b juvenile. Shorter and yellower bill than adult; legs reddish. Yellow-billed Chough P. graculus 2a adult. In flight, note wings less rectangular than those of Red-billed, with primaries shorter and less fingered; tail longer than width of wing base and slightly rounded at tip. 2b juvenile. Dingy bill and dusky legs, latter brownish to first summer. Eurasian Jackdaw Corvus monedula 3a. adult of race spermologm (western Europe). 3b juvenile of race spermobgus. Nape darker than that of adult; iris dark. 3c adult of race soemmerringii (eastern Europe and Asia). Very pale grey nape, often with obvious whitish basal collar. Daurian Jackdaw C dammcus 4a adult. (Short-lived juvenile plumage stage is similar but duller.) 4b immature. Differs from adult Eurasian in having darker grey nape, dark iris, silver streaks on sides of head and deep black of throat extending onto breast. Last two features important as dis­ tinctions from juvenile Eurasian. Birds acquiring pale collar are at first very pale on upper nape, remaining dark on lower nape (reverse of Eurasian, which is palest on lower nape). Fig. 3 is taken from Crows and Jays by Steve Madge and Hilary Burn, and its inclusion in colour in British Birds has been sponsored by the book's publisher, Christopher Helm Publishers