Yellow Wagtails present some of the greatest identification difficulties of all. The proliferation of forms and plumage variation create a veritable minefield, while the addition of intergrade and aberrant plumages to the mix only makes matters worse. This article focuses on one main identification angle: the separation of Yellow Wagtail from Citrine Wagtail in spring and autumn.
Yellow Wagtail
The British subspecies of Yellow Wagtail, M f flavissima, is still a familiar bird in much of Britain, though it has suffered significant recent decline. The Atlas of Breeding Birds in Britain and Ireland (1976) put its population at 25,000 pairs with a range extending as far north as southern Scotland. Today, sadly, much has changed. The population is now estimated to be no more than 15,000 pairs, while its range has also contracted.
Changing land use is largely to blame. The wet flood meadows favoured by this species are among the most diminished habitats in Britain and, unsurprisingly, Yellow Wagtail is one of our fastest-declining breeding birds. Flavissima is, however, still much commoner in Britain than any of its European cousins: Blue-headed, Grey-headed, Ashy-headed, Spanish and Black-headed Wagtails.
Citrine Wagtail
This species breeds across most of Asia, from European Russia in the west to north-east China in the east and from Tibet in the south to the Arctic Ocean in the north. For some years it has been spreading westwards and is now a regular breeder as near as Poland.
Formerly a great rarity in Britain (the first was only identified in 1954), this species is becoming steadily commoner and has now amassed almost 300 records. Most are of young birds in early or mid autumn but, interestingly, they seem to be arriving increasingly early, suggesting that at least some are coming from nearer breeding populations.
Traditionally a ‘Northern Isles in September’ bird, the best chances are now in southern England in August, and indeed the species is near annual in this month on Scilly. Spring records are also on the rise. Formerly extremely rare at this season, records are now annual in south-east England, again suggesting overshooting from breeding areas in eastern Europe. Unlike Yellow Wagtail, therefore, this is a species which is on the up.
Identification in spring
In spring the differences between the Yellow Wagtail subspecies are at their greatest. Males of the scarce or rare continental European forms are either ‘blueheaded’ or ‘dark-headed’, so a search for Citrine Wagtail will only need to eliminate the ‘common’ British form.
Typical British males are a beautiful bright daffodil yellow on the head, with a subtle pale green eyestripe and crown and plain yellow ear coverts. The underparts are also bright yellow, while the upperparts are a pale grey-green with yellow wing-bars.
There is, however, significant variation. Some show a rather darker eyestripe and crown (resembling the East Asian taivana form of the now-split Eastern Yellow Wagtail), while others show an almost entirely yellow head (inviting comparison with the West Central Asian lutea subspecies of Yellow Wagtail, which like taivana Eastern is unrecorded in Britain). Rarely, aberrant male British Yellow Wagtails show a grey mantle, resembling Citrine Wagtail.
Spring female British Yellow Wagtails are much duller than males, being creamy below and dull grey-green above. The intensity of the yellow and green hues is quite variable and some can look rather ‘cold’, but most show yellowish hues in the face, vent and undertail coverts and all show a well-marked slightly ‘intense’ facial expression caused by a darkish eyestripe and a prominent though thin supercilium. Females of some other Yellow Wagtail forms can be greyer than female British birds, but the variation is great and most are not safely separable.
Spring male Citrines are stunning. They are a pale lemon yellow on the head and underparts (though the undertail coverts are white), the head is unmarked yellow, the upperparts including the rump are a pale, pure grey, the wing-bars are broad and bright white and there is a prominent smudgy black ‘collar’ on the nape. The extent of this collar varies, however, and some birds also show some faint dark marks in the crown.
Spring females are also very attractive. They are wholly grey above with bold white wing-bars. The crown is grey, as are the ear coverts, and there is a bold yellowish supercilium and rear ear-covert surround. The underparts are also washed pale yellow, but the undertail coverts are white.
Identification in autumn
Later in the year, most Yellow Wagtails will be juveniles or first-winters. These present the greatest identification risks for Citrine Wagtail. Most young British Yellow Wagtails are strongly olive toned above and creamy yellow below, especially on the vent and undertail coverts. The face pattern is ‘intense’, with a strong eyestripe, including on the lores, and a prominent though thin supercilium with no rear ear-covert surround. The wing-bars are generally thin and creamy toned and the bill is normally pale based.
The main problem lies with paler, greyer and whiter individuals and vagrants of other European and even eastern Asian forms. These may superficially resemble Citrine Wagtail, but can generally be identified by close reference to their face pattern, undertail coverts and wing-bars.
Juvenile and first-winter Citrine Wagtail is a beautiful crisp grey-and-white bird, as much like a White Wagtail as
a Yellow. The upperparts including the rump are a pure pale grey, the supercilium is white, long and bold and there is normally a prominent rear ear covert surround (though this can be less obvious at range). The ear coverts are pale grey and often pale centred, giving a rather ‘hollowed-out’ look, while the lores are generally pale and only weakly smudged, imparting a rather ‘soft’ facial expression. The bill is wholly dark.
Other facial features include a rather pale forehead and neat dark sides to the crown. The underparts are white, though yellow is acquired in the face as the moult to full first-winter plumage progresses. The wing-bars are bold and pure white and the undertail coverts are always white.
Vocalisations
At all seasons, calls are among the most useful clues. British Yellow Wagtail generally gives the familiar high-pitched sweeip. Blue-headed and Grey-headed Wagtails (the commonest of the scarce or rare forms) also give this call.
A harsher sound is a strong indicator of a bird worth following up. Ashy-headed, Spanish and Black-headed Wagtails all give harsh calls, but these are very rare birds, and though possible in spring, are most unlikely in autumn. Such a vocalisation in autumn suggests either a Citrine Wagtail or, much rarer, an Eastern Yellow Wagtail. These all give a distinctive buzzy rasping dzeep which is very different from British and north-west European birds.
THREE: Male Citrine Wagtail (Sohar, Oman, 15 March 2006). This close-up image shows a complete suite of male Citrine Wagtail characters. The head and underparts are a pale lemon yellow (not a rich daffodil yellow) and there is typically some fine grey streaking in the crown. The blackish collar is rather weak on this individual, but the mantle is a lovely midgrey, the wing-bars and tertial fringes really broad and white and the undertail coverts are also white, here contrasting strongly with the pale yellow underparts.
TWO: Male Yellow Wagtail of the subspecies flavissima (Frampton Marsh, Lincolnshire, 17 April 2011). This male flavissima is typically bright daffodil yellow on the face and on the whole of the underparts, including the undertail coverts. The face pattern is more ‘intense’ than on Citrine Wagtail, a function of the greenish eyestripe and dark loral line, while the upperparts are a lovely moss green and the wing-bars are narrow and tinged with yellow. Surely, this is among the most attractive of our summer visitors.
FIVE: Female Citrine Wagtail (Ouessant, France, 21 May 2009). The combination of pale lemonyellow head and underparts, white undertail coverts, grey upperparts and strikingly contrasting wing-bars and tertial fringes renders this bird readily identifiable as an adult Citrine Wagtail. However, it lacks the black nape collar and plain-looking head of a male, showing instead the typical female pattern of grey crown, weakly smudged lores, dark eyestripe and lower ear covert border, combined with pale-centred ear coverts and a prominent pale rear ear covert surround.
FOUR: Female Yellow Wagtail of the subspecies flavissima (Seaforth, Lancashire, 23 April 2007). This British Yellow Wagtail is very bright and its underparts are a rich, saturated, rather golden yellow. The face pattern is typically ‘intense’, with greenish eyestripes and dark lores, while the upperparts are similarly green toned. Importantly, the undertail coverts are strongly suffused with yellow. Note that on this bird the wing-bars are a little whiter, but they are still narrow and lack the vivid contrasts shown by Citrine Wagtail.
SIX: Female Yellow (Blue-headed) Wagtail of the subspecies flava (Lesvos, Greece, 7 April 2006). This bird shows the classic pattern of a female Yellow Wagtail sensu lato. The throat and upper breast are typically whitish, merging rather messily into yellow on the belly, flanks and undertail coverts. The upperparts are also typical: a bright moss green with narrow, unexceptional wing-bars. Many female Yellow Wagtails elude precise subspecific identification, but this bird shows strong bluegrey hues in the crown and ear coverts and a long and broad white supercilium – sufficient to identify it as a Blue-headed Wagtail.
SEVEN: Juvenile Yellow Wagtail of the subspecies flavissima (Seaforth, Lancashire, 28 August 2011). This juvenile Yellow Wagtail has subtle green hues in the upperparts, an ‘intense’ facial expression caused by a strong dark loral line and eyestripe and solidly dark ear coverts with no pale rear surround. Furthermore, the wing-bars are narrow and blurry and the undertail coverts are strongly washed yellow. This combination of features is diagnostic of young Yellow Wagtail and readily eliminates any thoughts of Citrine.
EIGHT: First-winter Citrine Wagtail (Ouessant, France, 2 September 2006). At first sight this bird looks as much like a White Wagtail as a Yellow. It is entirely grey and white, lacking any trace of green or yellow hues. The lores are smudged and the pale-centred ear coverts are framed in dark. The supercilium is strong and pure white and bordered above by dark crown sides, while the pale rear surround to the ear coverts is present, though a little obscured by the bird’s posture. The upperparts are pure grey, the wing-bars and tertial edges are broad, bright and contrasting and the undertail coverts are white.
NINE: Juvenile Yellow (Blue-headed) Wagtail of the subspecies flava (Groningen, The Netherlands, 25 July 2005). This very young bird shows the characters of a full juvenile, particularly in its heavy crown-side blotching and strong dark malar and breast markings. As can be typical of European birds, it looks much greyer than British birds, but still does not approach Citrine Wagtail. In particular, its wing-bars are narrow, greyish and diffuse, its loral line is strong, there is no pale rear ear covert surround and the undertail coverts are, albeit subtly, washed a pale yellow.
ELEVEN: Male Yellow (‘Channel’) Wagtail flavissima x flava (Venus Pool, Shropshire, 17 April 2012). This bird is an intergrade. Its body and wings appear normal for a Yellow Wagtail: strongly moss green above with weak wing-bars and rich golden yellow underparts reaching all the way to the undertail coverts. However, its crown and ear coverts, although grey, do not match the rather dark blue-grey of Blue-headed. Instead they are a very pale soft colour. The ear coverts are strongly pale centred and there is much white in the throat. The bird is a fairly typical example of a Yellow x Blue-headed Wagtail from northern France, known as ‘Channel Wagtail’.
TEN: Male Yellow (Blue-headed) Wagtail of the subspecies flava (Flevopolder, The Netherlands, 24 May 2004). This gorgeous portrait illustrates perfectly the characteristic blue-grey crown and solid blue-grey ear coverts of this form, while the white supercilium is typically both long and broad, including before the eye. Blue-headed Wagtails vary in the amount of white in the throat. Many are wholly yellow-throated while others, as here, show white in the malar area, with the central throat (just visible here) still strongly yellow. There is therefore no need to consider a hybrid or southern European origin for this bird.
TWELVE: Male Yellow (Grey-headed) Wagtail of the subspecies thunbergii (Novgorod, Russia, 2 July 2004). The combination of Ashy-headed Wagtail-like dark head and a yellow throat can only mean Grey-headed Wagtail. As with the Ashy-headed Wagtail above, this bird shows a small pale spot behind the eye, either a sign of intergradation with Blue-headed Wagtail or, more likely, something within its normal range of variation. Grey-headed Wagtail is a regular, though still scarce, spring migrant in Britain en route to its breeding grounds in Scandinavia and Russia.
THIRTEEN: Male Yellow (Spanish) Wagtail of the subspecies iberiae (Ebro Delta, Spain, 13 June 2011). With its blue-grey crown and ear coverts, this bird most resembles a male Blue-headed Wagtail. However, its white throat is too extensive for even the most whitethroated birds of this form, while its supercilium is a little on the narrow side, particularly before the eye. This combination of features is highly indicative of Spanish Wagtail, an identification confirmed by the fact that the bird in Spain. A harsh call may be expected from this bird, though some can sound like flavissima.
FOURTEEN: Male Yellow (Ashy-headed) Wagtail of the subspecies cinereocapilla (Tuscany, Italy, 30 March 2009). The dark ashygrey head and white throat of this bird immediately attract attention. The lack of a supercilium and the white central throat rule out Blue-headed Wagtail, while the dark lores are striking. The presence of a small pale spot behind the eye may be an indication of intergradation with Spanish Wagtail, but may equally be part of the normal variation in this form. This bird might give a harsh call unlike northern European subspecies of Yellow.
FIFTEEN: Male Yellow (Black-headed) Wagtail of the subspecies feldegg (Tuscany, Italy, 4 April 2008). This form is perhaps the most striking of all. With its full glossy black hood, Black-headed Wagtail resembles no other Yellow Wagtail form, though darker-headed examples of Grey-headed Wagtail may on occasion bear a passing resemblance. Blackheaded Wagtails are generally regarded as yellow throated, though some, as here, can show a little white at the throat-sides. As with the other southern forms, Black-headed Wagtail has a strikingly harsh, rasping call.