Distinguishing Little and Reed Buntings

Transcription

1 British Birds VOLUME 69 NUMBER 12 DECEMBER I976 Distinguishing Little and Reed Buntings D. I. M. Wallace Plates Peterson et al. (1974) stated that Little Buntings Emberiza pusilla are 'distinguished from female Rustic and Reed Buntings \E. rustica and E. schoeniclus] by smaller size and dull chestnut cheeks'. Other field guides make similarly facile statements. All but one are content to feature illustrations only of adult males. Thus, none stresses the very real danger of confusion between Litde and Reed, to which the files of the Rarities Committee bear frequent witness and which is perhaps best exemplified by the unfortunate publication, in Vdr Fdgelvdrld (1965, 24(1): opposite page 17), Birds of the World (page 2468) and Collins Colour Guide (page 217), of a photograph of a young female Reed labelled as a Little. This paper, which stems from correspondence between observers in Britain and Sweden in 1974 and 1975, follows the publication of a useful, well illustrated comparison of the two species by Svensson (1975b), and attempts to reduce some of the evident risks in small bunting identification. It deals with size and structure; plumage; briefly, habitat and behaviour; and calls. SIZE AND STRUCTURE Typical Little Buntings are indeed little buntings, being shorter than, for example, Meadow Pipits Anthus pratensis and Tree Sparrows Passer montanus. The size comparison with Reed Buntings is less easy, for, while female Littles are always smaller than female Reeds, some large male Littles overlap, at least in wing length, with them. In addition, a few male Littles have wings as long as the smallest male Reeds. In the cases of these larger individuals, the size differences {BTU. Birds, 69: , December 1976] 465

2 466 Little and Reed Buntings may be less than 2 mm, and practically invisible in the field. Thus, while normal Littles are (and appear) distinctly smaller than Reeds, it must be noted that many observers have seen peculiarly small, presumably runt Reeds (both adults and immatures) and caution is essential over the character of size as a single basis for identification. For a fuller treatment of measurements, reference to Witherby et al. (1938) is recommended. Happily, there are more differences in character than those relating to size. These stem from structure and, though rather subtle, they form important clues. Bill shape The bill of the Little Bunting is not short and its shape is characteristic, with a rather long, triangular outline and a sharp point; the culmen is usually straight or even slightly concave (Svensson 1975, R. H. Dennis in litt.). The bill of the Reed, though in fact longer, is quite large and looks rather short. Its shape is essentially triangular, but the base is deep and rather bulbous; the outlines of both mandibles are slightly convex. (The degree of convexity, together with bill depth and general size, increases in the populations of Reed Buntings inhabiting Austria, parts of the Mediterranean area and all of eastern Europe.) Head shape The Little Bunting has a rather small head, a flat sloping forehead and an evenly rounded crown, the last feature contributing to a rather neckless appearance. Its round appearance is enhanced by the contrast between the rich chestnut of the head and the greyish cast of the mantle. The Reed has a larger and more angular head, often with an obvious fore-crown angle, pronounced rear-crown and, usually, more elongated neck. Again, the head shape is often exaggerated by the paleness of the nape collar in males, also shown by some females and immatures. Body shape In photographs, migrant Little Buntings look dumpy, with a configuration recalling Linnets Acanthis cannabina or Tree Sparrows. Such comparisons, a stress on compactness and even allusions to a 'hunch-backed' appearance are frequent in recent British records and, in this respect, their resemblance to Dunnocks Prunella modularis can be striking (R. J. Johns in litt.); this extends to feeding manner and hopping gait. Older references mention slimness (with compactness) for Little, recalling pipits Anthus spp. This is indicated in the photographs of breeding birds published by Svensson (1975b), but it is not recorded for migrants.

3 Little and Reed Buntings 467 By contrast, the Reed Bunting has a rather long body, made more attenuated, as in most buntings, by the pronounced extension of the tail. Only very exceptionally does it recall a small finch (Fringillidae) or a dainty sparrow Passer sp. Even small Reeds retain the rather high-headed, evenly-contoured, long outline of larger individuals. Folded wing shape Wing shape may be difficult to observe, but, as pointed out by Svensson (1975a and b), there are important differences in this character. The primary emarginations of Litde Buntings fall almost directly below the tips of the secondaries, whereas those of Reed Buntings fall well inside that position. The spacing of the primary tips is also dissimilar. Only four tips are easily visible on Littles, and two (5th and 6th) cover most of the wing point. Reed Buntings, however, show five tips; their spacing is rather even, but the longest (5th) is almost masked by the next (6th). The determination of these differences in spacing requires exceptional skill in observation. Tail length and shape Owing to wide variations between individual Reed Buntings, the difference in tail length between the two species is not constant. It can be as little as 2 mm. Thus, short-tailed Reeds are a particular danger. There is, however, a pronounced difference in tail shape. The tail ends of Reeds are usually full and rather loose, this character being obvious in flight and on the ground, where it is often exaggerated, not only by flicking, but also by an obvious and characteristic 'nervous' spreading of the outer feathers. The tails of Littles, even when spread, are essentially rectangular and, when folded, look noticeably thin, particularly from behind. In the opinion of R. H. Dennis, R. J. Johns and myself, they are flicked, but not spread in alarm (contra Harris 1957). Leg length The Little Bunting has short legs, and these clearly account for the Dunnock-like shuffle already referred to above. It hugs the earth. The Reed, on the other hand, has legs as long as those of the Yellowhammer E. citrinella. They can exceed those of the Little by up to 25%, and the stance of Reeds on the ground is usually quite upright. Flight silhouette and action A Little Bunting looks compact, neat and rather 'busy' in flight, being difficult to follow in a flock of Linnets, for example, in a way that a Reed is not. Its configuration is not outstanding.except for the noticeably rectangular tail. The Reed Bunting looks long and rather

4 468 Little and Reed Buntings free, yet jerky, in flight, being easy to follow. Its configuration is very individual, with wings apparently set well forward, and tail length and flexibility very obvious. Its flight action is also distinct, being rather pipit-like, with noticeable bursts of wing-beats (sometimes seemingly uneven), most obvious from behind. Many of the characters discussed above will be seen only with practice and, since the Little Bunting remains a rather scarce vagrant in western Europe, this is best obtained with the Reed, which can be studied the whole year round. PLUMAGE There has been considerable confusion over plumage differences between Little and Reed. There is not much published information on the appearance of the former in the field (and notes on it in this journal have contained comments that now seem odd). Rather than add to the confusion with a plethora of age and sex comparisons, I have concentrated in table i on isolating plumage features that are either diagnostic or strongly indicative of the species in most plumages. There is, of course, no possible error with an adult male Reed in breeding plumage, which is not included in table i. There remains the matter of bare part colours. Little usually shows a paler bill than Reed, recalling that of a Redpoll Acanthis Table i. Plumage differences between Little Buntings Emberiza pusilla and Reed Bantings E. schoeniclus, other than adult males in breeding plumage Plumage area LITTLE REED Centre of crown Lateral crown stripes Supercilium Eye ring Typically pale chestnut in adults, but variable in immatures: some as adults, but others paler or yellower, even streaked grey or brown; colour palest at front Distinct, typically black in adults, but dark blackish-brown or even chestnut in some females and most immatures, on which black feather bases obscured by paler fringes and tips Wide, obvious behind eye (forming upper part of pale surround to cheek), always buff, tinged chestnut before eye and distinctly paler behind it Very distinct, cream or pale buff on most, off-white on some, paler than supercilium and contrasting with dark cheek Typically dull brown, but very variable in immatures: often paler and even yellowish-buff Very variable, dark brown on most, but often paler, even bright chestnut in some immatures, also blackish in young males in spring Not obvious in most (with less contrast with cheek), dull brownish-white, rarely yellowish Indistinct, colour as supercilium

5 Little and Reed Buntings 469 Table 1 (continued) Plumage area HEAD Cheek Malar stripe Moustache Bold patch, typically almost uniform chestnut in adults, duller, yellower in immatures, often with paler spot at rear and with black edges or patch usually obvious behind eye, round or on rear half but never with lower outline extending forward of point below eye Cream or buff in most adults, but usually white in immatures, when obvious Obvious, black, usually broadening at base Obvious, typically mottled dull brown, but chestnut in some, widi dark surround (blackish in some males) most obvious behind eye and along lower half, with dark outline reaching base of lower mandible Obvious, white to pale greyish-buff Pronounced, usually heavy dark brown or black line, generally broadeningjinto large smudge at base UNDERPARTS Chin and throat Streaks Variable, buff, even chestnut in adults (distinctly warmer than rest of underparts), white or pale cream in immatures Typically short, fine and discontinuous black (looking 'clean' against white ground colour) Typically white, washed yellow or buff, but greyishbuff in some, never contrasting with rest of underparts Typically rather long, often diffuse and usually continuous; dark brown, looking 'messy' against dull ground colour UPPERPARTS General colour Lesser wingcoverts Typically rather dull, even greyish-brown, less warm than head, but bright and rather 'coppery' in some Indistinct, dull brown and not contrasting with rest of upperparts Wing bars Obvious, particularly on median (tips of coverts, pale buff, even off-white, median and distinctly paler than covert fringes greater coverts) Tertial Distinctly pale, but not broad fringes Rump Chestnut or brown, indistinctly streaked Typically bright, pale brown and even chestnut, but duller and colder in some Very distinct, bright chestnut or bay, forming most colourful mark on many females and immatures Very indistinct, pale chestnut and only very slightly paler than covert fringe Very distinct, pale and noticeably broad on outer webs Typically grey-brown, but brown in some females, even buff in some immatures, with virtually no visible streaks

6 47 Little and Reed Buntings Jiammea in having pale brown or ochre on the lower mandible at least and also on the cutting edge and base of the upper (per RHD). It never has a blackish bill like some male Reeds. The legs of Little are usually paler and cleaner than those of Reed and can show a pronounced pinkish tone. Although the head pattern of typical Littles can be very obvious, it is likely that, of the characters analysed in table i, only the following are foolproof: eye ring, fore-cheek pattern and lesser wingcoverts. I must stress the very real chance that some immature male Reeds in spring can exhibit head patterns very close to that of Little and that, in autumn, some birds are extremely confusing. Young Reeds with apparently chestnut crowns and cheeks look very unlike their usually drabber selves and clearly cause confusion to many observers. In such cases, and in those of poorly marked Littles lacking strong black on the crown edges, it is important to try for the other certain characters. Begin with the eye ring seems to be the new golden rule. Finally, I must note my complete failure to support the suggestion that a pair of pale back stripes is diagnostic of Little (Harris 1957, disputed by Svensson 1975b). This character is common to several species of buntings and is irrelevant to the distinction of the two under discussion here. HABITAT AND BEHAVIOUR Differences in breeding ecology are swamped in the exigencies of migration, but it is apparent that migrant Little Buntings rarely enter woody cover, even where their preferred scrub willow Salix exists. They are found most frequently in crops, on disturbed soil or on paths and roads, appear to feed almost exclusively on seeds or ground insects and tend to go to ground rather than to cover when flushed. They have a reputation for being tame, but also have the remarkable ability to vanish in minimal vegetation. Migrant and wintering Reeds are virtually ubiquitous in vegetation, now being independent of their original waterside niche, and may be seen feeding in trees with Chaffinches Fringilla coelebs and on shingle with Snow Buntings Plectrophenax nivalis. They may go to ground when flushed, but usually first perch on a tall weed or the edge of dense cover in order to observe their disturbers. Migrant Reeds are often wild and secretive and the flocks of Scandinavian migrants that visit Britain may bring Little Buntings with them as well as Rustic Buntings. GALLS The voice of the Little Bunting has been incompletely studied, but migrants certainly utter two short monosyllables {or two distinct variants of one) and perhaps a third. According to Svensson (1975b),

7 Little and Reed Buntings 471 the most common call is a hard, sharp, clicking 'zik', recalling a Hawfinch Coccothraustes coccothraustes. This note is also rendered 'tic', 'tick', 'tzik', 'pick' or 'pwick', and also recalls a Rustic Bunting or a Robin Erithacus rubecula. The description of the last transcription as 'slightly rising' (L. S. V. Venables, in Witherby et al. 1938) is disliked by Swedish observers, who opine that the monosyllable is invariably flat in tone. British observers, however, have distinguished two types of clipped monosyllables, that above and a quieter, lower, dry 'tip', 'stip', 'tsip' or 'tsitt', also written 'tick', 'twit' or 'pwit', again recalling a Robin or a Song Thrush Turdus philomelos. Several recent records feature monosyllables ending in both hard and soft consonants, and there can be no doubt that Little Buntings give more than one variety of call on passage through Britain. Furthermore, both types noted above may be quickly repeated in series (usually twice or thrice) from the ground and in flight. Svensson (1975b) doubted Venables's (1949) ascription to the Little Bunting of a higher, more musical 'tsew' call than that of Reed, and several British observers familiar with Little are also wary of this call, now again enshrined by Heinzel et al. (1972); two recent records of problematic Littles giving it were rejected by the Rarities Committee. Having personally learnt from Venables the need for care in voice notation, I am reluctant to exclude the 'tsew' call from the list of those uttered by Little, and it should be noted that two other not dissimilar monosyllables are given by breeding birds. These are a short, slightly hoarse 'tse', recalling a Spotted Flycatcher Muscicapa striata, and a quiet 'tseee', again recalling a Robin and, in fact, common to several buntings when inactive on territory (L. Svensson in litt. and 1975b). Only one other note is on record for Little: a thin 'kit', given by adults to fledglings (Svensson 1975b). The voice of the Reed is much better known, but the transcription of its rather variable notes is not easy. Migrant calls include a very typical, quite loud, plaintive 'tsew', often given in alarm or during escape flights; a quieter 'tsip' or 'chit', also associated with alarm; a penetrating, metallic, ringing 'chink' or 'tzing', apparently a contact call; and a loud, clear 'tzeek', 'tscheek' or 'tseep'. Breeding Reeds also utter a quiet, reflective 'tsee'. There is the obvious danger that several of the above transcriptions of calls could relate to either species, but I have no evidence that the Reed ever utters any note like the 'tzik' or 'tick' of Little, or repeats any of its notes in rapid series. RHD [in litt.) has stressed the absence of any 'tick' note from the vocabulary of the Reed Bunting. OTHER CONFUSION SPECIES Several Asiatic buntings that normally migrate within the east Palearctic have straggled west to Europe, and three small species

8 472 Little and Reed Buntings merit brief discussion in the context of this paper. The Chestnut Bunting E. rutila (France, the Netherlands and a candidate for category D in Britain) is larger and more thickset than the Little Bunting, and even the less chestnut females and immatures are quickly separated by their rufous rumps, strongly yellowish underparts and lack of obvious white in the tail. The Pallas's Reed Bunting E. pallasi (Denmark and, under review, Britain) is essentially a miniature Reed, but at all ages it differs from both that species and Little by its paler appearance, notably on the rump, which can appear pale grey or even white. Female Pallas's Reeds have chestnut cheeks, but no striking crown pattern. Potentially much more troublesome is the Yellow-browed Bunting E. chrysophrys (France, Belgium and, under review, Britain). Like the Chestnut, however, it is a plumper bird than Little, and males present no problem, since their basically black heads are obviously marked by a white crown stripe widening on the nape, a sulphur yellow supercilium and a whitish cheek patch. Females and immatures somewhat resemble dull Litdes, but are easily separable by their less uniform plumage colour, the lack of any striking head pattern and their relatively much larger, finch-like bills. ACKNOWLEDGEMENTS This paper has taken two years to write. I am particularly indebted to Lars Svensson for a most informative series of letters and advance drafts of his texts. R. H. Dennis, P. J. Grant and R. J. Johns made typically expert comments on an early draft and RHD also supplied the slides from which plates were prepared: I thank them very much. I am also indebted to R. E. Emmett, who chased several small buntings with me, I. C. J. Galbraith, who provided access to the bunting skins at the British Museum (Natural History), and the members of the Rarities Committee, who commented in detail on the files of both accepted and rejected Little Buntings. SUMMARY AND CONCLUSIONS Observers who find a small, nondescript bunting, and who not unnaturally think of Little Bunting Emberiza pusilla, will find insufficient text or illustrations in field guides to support the identification of any but the most obvious male. The danger of mistaking small or oddly plumaged Reed Buntings E, schoeniclus for Littles is considerable. Except in adult male plumage, Little and Reed Buntings present very real identification problems. The main points distinguishing Litde are: more pointed bill; neckless, hunch-backed appearance; thin, rectangular tail; short legs and shuffling gait; pale eye ring; uniform, chestnut cheeks (yellowish in immature); dull brown lesser wing-coverts; and ticking call note. REFERENCES HARRIS, G. L 'Little Buntings in Surrey'. Brit. Birds, 50: HEINZEL, H., FITTER, R., and PARSLOW, J. The Birds of Britain and Europe with North Africa and the Middle East. London. PETERSON, R. MOUNTFORT, G., and HOLLOM, P. A. D A Field Guide to the Bird of Britain and Europe. London. 3rd edition.

9 Little and Reed Buntings 473 SVENSSON, L, 1975a. Identification Guide to European Passerines. Stockholm, 2nd edition. 1975b. 'Little Bunting and female Reed Bunting the problem of field identification'. V&rF&gelv., 34: VENABLES, L. S. V 'Call of Little Bunting and song of Bluethroat'. Brit. Birds, 42: 182. and VENABLES, U. M Birds and Mammals of Shetland. Edinburgh and London. WITHERBY, H. F., JOURDAIN, F. C. R., TICEHURST, N. F., and TUCKER, B. W The Handbook of British Birds. London, vol. I. D. I. M. Wallace, g Woodhill Rise, Heads Lane, Hessle, Hull, North Humberside HU13 OHZ

10 PLATE 50. Left (1-4), Little Buntings Emberiza pusilla; right (5-8), Reed Buntings E. schoeniclus. Little Bunting: 1 breeding adult, 2 immature (October), 3 as 2 but with black crown stripes obscured by pale tips (frequent), 4 as 3 but crown stripes appearing almost uniform chestnut (very rare), top left flight silhouette. Note fine triangular bill, eye ring, buff face of adult (1) but white throat of most immatures (2,3), wing-bars, sharp streaks on clean underparts and pale central crown reaching bill. Compare with Reed Bunting: 5 male in first spring moult, 6 immature (September) with pale head striped chestnut on crown (infrequent), 7 immature with dark head and heavy markings (frequent), 8 female or immature (October) of typical appearance. Note stubby bill, lack of obvious eye ring, pronounced moustache (not 6) spreading into long, diffuse streaks on usually dull underparts and variable head pattern lacking pale central stripe reaching bill (even on 6). Note also nervous spreading of tail (8). {Pencil drawings from photographs and field sketches: D. I. M. Wallace)

11 PLATE 51. Little Bunting Emberiza pusilla, caught for the purpose of ringing, Fair Isle, Shetland, October 1967 {photos: R. H. Dennis). Note: distinct pale eye ring; uniform cheek patch, except for pale spot at rear, with black lower outline hardly reaching to eye, and not to bill (which it does in Reed Bunting E. schoeniclus); rather long, triangular, pointed bill; short legs; crouching attitude; flat, sloping forehead; and neckless, hunch-backed appearance