Identification of Female Pine Buntings Colin Bradshaw and Martin Gray

Identification of female Pine Buntings Colin Bradshaw and Martin Gray

ontroversial birds are a double-edged sword for the British Birds Rarities C Committee. They take up an inordinate amount of members' time and effort, but out of this frequently comes a clearer understanding of a complex problem. It is rather more frustrating if, after all the effort expended, we are only a little nearer the Solution than when we started. Such is the Situation with the 'Big Waters bunting', present in Tyne & Wear from 18th February to 16th March 1990. Was it a Rne Bunting Emberiza kucocephalos, as originally claimed, a Yellowhammer E. citrinelk, perhaps of the less-yellow eastern race erythrogenys, or even a non-yellow Yellowhammer as others have maintained (and do genuinely non-yeüow Yellowhammers really exist?), or was it perhaps even a hybrid between the two species? On first circulation to the Committee, nine members voted to 'pend for more information' and one to reject on the grounds that female Pine Buntings are probably not identifiable in the field. Two subsequent claims of female Pine Bunting, from North Ronaldsay, Orkney, on 12th-13th October and lst- 5th November 1991, were also 'pended'. When such an impasse occurs, the BBRC frequently enlists the help of outside experts, often from abroad (which helps to explain why some records of 'difficult' birds take a long time before a final decision is reached). On this occasion, we sought help from three bunting experts, two of whom opted for Pine Bunting (with detailed reasons why) and the third From the Rarities for Yellowhammer (without giving reasons). Following Committee's files much discussion, and in the uncommon Situation where Sponsored by 'present knowledge' was insufficient, the BBRC decided to 'go public' on this issue and to discover what other IZEISS sources of information and opinion could be tapped by explaining the current position and various personal Germany views.

378 \Brit. Birds 86: 378-386, August 1993] Identification offemale Pine Buntings 379 Big Waters bunting, 1990 This bird has appeared in words and photographs so many times over the past two years that there can be few who are unaware of its general appearance. Since it was at a feeding Station for a month, thousands of birders were able to watch and photograph it at close ränge (plates 124 & 125). Initially, it was provisionally identified as a female Pine Bunting on the following characters: (i) it stood out from the Yellowhammers present in being noticeably pale, especially on the mantle, which was a cold, pale grey-brown; (ii) in the Seid, despite close and detailed scrutiny, it showed no visible yellow; all other plumage colours appeared normally saturated, making leucism less likely; (iii) the fringes of the primaries were a gleaming white, with no hint of yellow; (iv) a very prominent white submoustachial stripe curled behind the ear-coverts and joined a pale grey nape side; (v) the belly was white and unstreaked, extending as an inverted 'V into the lower breast; (vi) the lesser coverts were a uniform grey-brown, with no hint of Yellowhammer's pale notching. In addition, it showed several other features, many of which CB had noted on Pine Buntings in Siberia: (i) a prominent white eye-ring; (ii) a distinctly bicoloured bill, with dark upper and pale lower mandible; (iii) a whitish central nape spot bordered on each side by a short dark bar; (iv) a row of thin streaks on the white throat, with an isolated crescent of unmarked white below (see fig. 1); (v) the cap was pale grey, but so heavily and regularly streaked as to appear uniformly dark, and it never showed the pale central crown present on many Yellowhammers (and some Pine Buntings). Controversy revolved around the general plumage tones of this individual. Why was it so cold and grey, with very little brown in the plumage? It seemed unlikely to be leucistic, as the rufous on the rump, tertials and lowest row of scapulars appeared normal. Admittedly, it did become marginally browner during its stay and some chestnut became visible in die streaking on the breast sides, but, given the limited Information available in the literature, it seemed difficult to believe that a Pine Bunting could be this cold.

Fig. 1. Head pattern of presumed female Pine Bunting Emberizfl laxocephalos, Big Waters, Tyne & Wear, February/March 1990 {Martin Eccks). Note: prominent white submoustachial stripe, white eye-ring, bicoloured bill, row of thin streaks on white throat with isolated crescent of unmarked white below, heavily streaked crown with no pale central streak

Identification of female Pine Buntings 381

FACING PACK 123-127. Fine Buntings Embaiza leucoaphalos and Yellow-hammers E. cibimlta

123. 'Fop left, female Pine Bunting, North Ranaldsay, Orkney, 1st November 1991 (D. Paltmcm)

124 & 125. 'Pop right and upper centre, 'Big Waters bunting' (see text), with Yellowhammers in lower photograph, Tyne & Wear, February 1990 (C. Braitshcuv}

126. Lower centre, putative hybrid between 'Big Waters bunting' of 1990 and Yellowhammer, with two Yellowhammers, Big Waters Reserve, Tyne & Wear, January 1991 (C. Bradshaw)

127. Bottom, male Pine Bunting with male Ycllowhammer, Northumberland, February 1992 {Eric Birdi

In a subsequent article on identification of female Pine Buntings (Birding World 3: 89-90), Ian Lewington highlighted the following as being important features: the crown streaking; pattern of the malar stripe; relative absence of streaking on undertail-covcrts; and the contrasting breast pattern, with blackish streaking in the centre fading to the sides. He concluded drat the Big Waters bird was an abnormally pale Pine Bunting: a conclusion that many found difficult to believe, feeling that this was either a normal Pine Bunting or a very abnormal Yellowhammer. Big Waters buntings, 1991 During January-February 1991, two unusual-looking buntings intermittently visited the feeding stations at the Big Waters Reserve. Bodi showed the same washed-out mantle coloration as the 1990 individual, but both had bright yellow primary edges and a pale yellow suffusion on tire belly; one also had a yellow throat (plate 126), while the other had an intriguing yellow spot in the middle of the crown. Again, both looked quite unlike any of the Yellowhammers present and were immediately striking owing to their pale plumage. The question then posed was: were these hybrids of the 1990 'Pine Bunting' with a Yellowhammer, or was there a 'non-yellow' gene in the local Yellowhammer population which manifested itself in these three birds in different ways? Expert opinions The BBRC sought advice on the identity of the three buntings, on the criteria useful in identifying female Pine Bunting, and on the identification of hybrids. We received detailed comments from Urban Olsson and Professor Eugeny Panov. Both thought that the original 1990 bunting was a female, that it was probably a first-winter, and that its coloration was within die normal range for Pine Bunting. UO pointed out that this coloration is due partly to broad pale fringes to the body and covert feathers obscuring the colours below (these were visible on tire photographs which had been sent); as the fringes wore off, 382 Identification of female Pine Buntings the bird would become less cold, darker and brighter. EP stated that the coloration of female Pine Bunting is rather variable, particularly with regard to the following characters, all of which vary more or less independently:

(i) light background to head, breast and belly plumage (varies from dull, dirty sandy to almost white); (ii) amount of dark markings on head and throat; (iii) amount of chestnut (feathers) on head and diroat; (iv) colour of dark streaks on sides of upperparts; (v) amount of white on nape; (vi) general colour of mande (which also tends to be slightly paler and duller in winter).

They differed in their opinions of the 1991 buntings. UO felt that these looked exactly as he would expect a hybrid to look, 'a sort of mosaic between mainly Pine Bunting-type pale plumage and uhen rather bright yellow colours in limited areas', but added that the only way to be sure would be through DNA analysis. EP felt that they were more likely to be first-year Yellowhammers with a limited amount of yellow, but that it was 'impossible to distinguish on phenotypical characters only between first-year Yellowhammer and first-year hybrids'. Bom enlarged upon the question of hybrids (see below). In contrast, Hadoram Shirihai consulted with colleagues in Israel, where both Pine Bunting and Yellowhammer winter. They came to the conclusion that the original 1990 bunting was a non-yellow Yellowhammer, but time and workload prevented HS from giving reasons.

Orkney buntings, 1991 In autumn 1991, MG, despite being on crutches, found two different female buntings on North Ronaldsay: on 12th-13th October, and on lst-5th November. Both gave excellent views and were identified as female Pine Buntings, the second being aged as a first-winter (plate 123). The most immediate feature of both was their general cold, pale plumage, which MG likened to die effect of a Common Redpoll Carduelis flammea of the 'mealy' race flammea in a flock of the 'lesser' race cabaret. Neimer was quite so cold as the 1990 Big Waters bunting, and both showed fairly obvious chestnut streaks on the breast sides (a very difficult feature to see on the Big Waters individual). These appeared to be more typical Pine Buntings, but bom records were 'pended' by the Committee while investigations were .carried out into the identification features of the species. What was noticeable from the descriptions of all three buntings was the large degree of overlap in features that were noted as 'different'. It is from these areas of overlap that the list of potential separation features (see below) is drawn up.

Male Pine Buntings, 1992 In February 1992, two male Pine Buntings turned up in England: in Northumberland, and at Dagenham, Essex. Many observers commented on just how cold and grey were the mantles of both. The Northumberland individual could easily be picked out among tire flock of mixed finches and Identification of female Pine Buntings 383 Yellowhammers by its mantle colour, which was markedly different from that of any of the accompanying Yellowhammers (plate 127) and was matched closely by some female House Sparrows Passer domesticus. The similarity of mantle colour to that of some pale, fresh-plumaged House Sparrows was noted also by observers of the 1990 Big Waters bunting. Photographs of the Dagcnham male suggest that it had a very similar mantle colour {Brit. Birds 85:'plates 204 & 207)'

Problems of hybrids and non-yellow Yellowhammers Correspondence from both EP and UO made us realise that our views on the probable appearance of hybrids were extremely simplistic and that birds like the 'Sizewell bunting' (Brit. Birds 83: 240-242, plates 142 & 143) were the exception rather than the rule. We can do no better than to quote Urban Olsson in full:

"How hybrids can be separated is a much more difficult question to answer, since second-, third-, fourth- etc. generation offspring of hybrids must look increasingly like one of the ancestors as the genes of one species become diluted. Any type of intermediate plumage must be possible and to be expected, up to the stage where tire plumage shows the characters of only one of the ancestors, but where there are still some genes left from the other species a particular individual does not look like. Clearly there could be cases where a trace of yellow could only be seen in the hand. '1 think we must admit to ourselves that this is a problem that can never be solved unless we actually analyse the genes. For all practical purposes I think we can accept a record of Pine Bunting if the bird in question shows all the characters of Pine Bunting and nothing contradicts that diagnosis such as is the case with the first bird [Big Waters, 1990]. I think it is most likely that a bird that looks just like a Pine Bunting actually is one, but I have no answer to how a true Yellowhammer without a trace of yellow in the plumage could be safely identified, if such a bird exists . . /

Professor Eugeny Panov also wrote at length on hybrids and supplied colour sketches of head patterns (fig. 2, on page 384). He stated that 'some hybrids may be identified as such only by means of examination in the hand, although such specimens occur comparatively seldom. I once caught, in the overlap zone near Novosibirsk, a female E. leucocephalos whose mate was a typical male E. citrinella. This female appeared to be a hybrid: she had yellowish bases to the crown feathers concealed under their white end parts, and also a vague yellowish belt along the middle of the belly . . .' There seems to be a somewhat greater problem with males. EP stated: 'In the sample of 239 adult hybrid males 58 specimens had a yellow tinge on a single, restricted, part of the plumage, namely on the wing in the region of the marginal undcrwing-coverts. I am not certain that this could be seen in the field . . .' He went on to mention the possibility of a pure grey bird: 'i.e. grey without any tinge of brown or yellow does not occur in species-specific coloration of Pine Bunting or Yellowhammer but does very rarely in some obvious hybrids. I saw such aberrant coloration in adult' male hybrids but never in females . . .' Alan Dean has raised the question of what such male hybrids might look like in first-year plumage. It would seem unlikely that they show more yellow, but which later disappears as they attain adult plumage. If not, then such an immature could show virtually no yellow at some stage. (A. R. Dean in litt.) 384 Identification of female Pine Buntings

Fig. 2. Pine Bunting Emberiza leucocephalos and Pine Bunting X Yellowhammer E. citrinella hybrids. B had a yellow tinge to primary fringes, and C had yellow primary fringes, both having other pale parts of plumage pure white; but note that such 'depigmented' hybrids may have no yellow at all, as in the case of D (redrawn by Martin Eccles from original colour sketches by E. Panov) Separating Pine Bunting from Yellowhammer Given all the preceding information, we feel that the following factors may help identify female Pine Bunting. No single feature by itself is enough, as the 'impression' of Pine Bunting is a composite of these features, but, equally, an absence of some of them would not necessarily go against the identification. We are sure, however, that the first three are essential, as also are prolonged and close views (or examination in the hand) and preferably some supporting photographs. Identification of female Pine Buntings 385 (1) The bird must show no trace of yellow anywhere, hence the necessity for prolonged, close views (many species initially appear cold-toned, only to reveal some yellow or olive on close inspection: e.g. "Siberian' Chiffchaff Phylbscopus mllybiSa tristis). (2) The edges of the primaries must be seen to be pure white. Occasionally, hybrids show their only obvious trace of yellow on these parts (see plate 126). The edges of the rectrices should be white or pale grey. (3) The ground colour of the underparts must be seen to be white or whitish, with no more than a grey, brown or creamy wash to throat and breast and becoming pure white on belly, vent and undertail-coverts. In addition, the streaked and unstreaked areas of the underparts should be quite discrete and create an inverted 'V when viewed from in front. (4) The lesser coverts should be a rather uniform grey or grey-brown, with none of the pale notches shown by Ycllowhammer. This feature can be very difficult to see, as the lesser coverts are usually hidden by the flank and scapular feathers. (5) The submoustachial stripe should be prominent, and white, off-white or pale grey. (6) There should be a pale nape spot bordered on each side by a dark bar, somewhat Eke a poorly marked female Brambling Frittgilla motitifiitigilla. (7) The bill is often longer, though perhaps no deeper, than on Ycllowhammer. Each of the three putatrve Pine Buntings had a distincdy bicoloured bill: dark grey upper mandible with paler cutting edge, and pale grey lower mandible. Some Yellowhammers' bills, however, can (though in our experience comparatively rarely) appear bicoloured. (8) All three showed white undertail-coverts with sparse, thin, dark shaft streaks. These are not a continuation of flank streaks, but appear de novo on the undertail-coverts. (9) Two of the three showed the feature described by Ian Lewington of a linear dotted pattern to the malar stripe, giving a composite prominent malar; this was not noted on the third, which was described as having well-defined malars. Each had a slight streaked extension from the malar, across the lower throat and isolating a white, unstreaked crescent below. We do not know whedier Yeliowharnmer can show these features. (See fig. 1) (10) Ail three showed heavy, close, dark, linear streaks on the forehead and crown, almost running together into a striated pattern; the cap looked dark at a distance, and only with better views was this seen to be caused by this streaking on a pale or, on the Big Waters bird, almost white ground colour. This was also decribed by IL, since when, however, CB has seen first-year Yellowharnmers showing the same feature, so it is not diagnostic of Pine Bunting (in addition, some female Pine Buntings show a pale area on the central crown), (11) Pine Buntings should show some rufous in tire breast and flank streaks. This can range from very obvious, as on the first North Ronaldsay individual, to almost impossible to see except in good light. This feature, when shown by Yellowhammers, appears less distinct, perhaps owing to the different ground colour. (12) Pine Buntings are often up to 10% bigger than Yellowhammers. Both the November North Ronaldsay individual and the February 1992 Northumberland male could be picked out immediately from accompanying Yellowhammers by this size difference. (i 3) The rump and the outer web of the feathers in the lowest row of scapulars seem a brighter rufous than on Yeliowharnmer (again, perhaps a result of the latter's lack of contrast). In addition, the three female buntings in question showed more-prominent narrow white fringes to the rump feathers, producing a scalloped effect (most noticeable on the lower rump). (14) Two of the three, and several Pine Buntings in Siberia, showed very distinct, clear-cut, white or off-white eye-rings. (15) The two North Ronaldsay females (and three previous males in Britain) all gave a distinctly different call, as well as many indistinguishable from Yellowhammer's: this call was a nervous, stuttering 'trr-rrr-rrr-ick' or 'prr-rr-rr-tt', given both in flight and from a perch. (16) The tips to the wing-coverts of Pine Bunting tend to be paler and more prominent on the median coverts than on the greater coverts, forming a distinct median-covert bar. Because of the notorious variability of this feature on many first-year buntings, however, we are unsure as to whether this is a reliable and constant difference between the two species. (17) Although not a usable field character, the underwing-coverts are white on Pine Bunting and yellow on Yeliowharnmer. 386 Identification of female Pine Buntings Conclusions Since the appearance of the two very grey-looking male Pine Buntings in February 1992, it does seem that the previous general perception of female Pine Bunting as being a brown-and-white bird may be inaccurate for winter and early-spring individuals. This had been based perhaps on faded museum specimens or experience of the species on its breeding grounds. The identity of these recent buntings, however, particularly the original Big Waters individual of 1990 and the two at the same locality in 1991, is still a matter of debate. Do Yellowhammers totally lacking yellow really exist? If they do, how do we prove that they are Yellowhammers? Are there any other features that may help separate these two species, and what arc people's views on the criteria listed above? Were the 1991 buntings hybrids between the 1990 individual and a Yellowhammer? We welcome comments, observations, and, particularly, answers to the above questions from observers with experience of both species. If no adverse comments are received on the suggested criteria, there are two possible courses of action. We can cither accept female Pine Buntings on these criteria, or adopt the approach of the Swedish rarities committee, which refuses to accept sight records of tristis Chiffchaffs as it is impossible to ascertain the absence of yellow (a similar case could be made for Pine Bunting). We would recommend the former action, as, surely, it is better to allow through the odd hybrid that looks identical to Pine Bunting than to reject all female Pine Buntings, which would completely distort the true pattern of occurrence. If the 'miracle diagnosis' is discovered in the future and proven by DNA testing, there is nothing to stop the BBRC reviewing all the old records, anyway. What is no longer open to doubt is that any putative female Pine Bunting will require the closest scrutiny or capture for a firm identification to be fully and conlidendy established.

Acknowledgments We are greatly indebted to Urban Olsson and Professor Eugeny Panov for initial and continuing help and permission to use the results of their experience and hard work; to Hadoram Shirihai For his original opinion; to members of the British Birds Rarities Committee, past and present, who have put in a lot <>F work on this species; to Alan Brown, Alan Dean, Martin Ecclcs, Eric Meek, Jimmy Steele, Keith Vinicombe, and staff oF North Ronaldsay Bird Observatory for helpFul comments; to Erie Bird, Ian fisher, Dave Patterson and George Reszeter for use of their photographs during preparation of this paper; to Peter Colston and the Natural History Museum, Tring, for access to skins; and to Martin Eccles for drawing Eg. 1 and for redrawing Professor Panov's diagrams (fig. 2).

Dr Colin Bradsfiaw, 9 Tynemouth Place, North Shields, Tyne & Wear NE30 4B~j Martin Gray, North Manse, North Ronaldsay, Orkney KW17 2BG