Studies of less familiar iy6 Barred Warbler D. A. Christie Photographs by A. jV. H. Peach and J. B. and S. Bottomley Plates 12-15 The French 'Fauvette eperviere', German 'S^rforgrasmiicke' and Swedish '.HoAsangare' are all vernacular names for the Barred Warbler Sylvia nisoria. The italicised parts of these continental names all mean Sparrowhawk Accipiter nisus and allude to the superficial resemblance between the two, a notion reflected in several other European names for the species; even the specific name nisoria means 'sparrowhawk-like'. In reality the only similarities are barred underparts and a long tail, but these features certainly distinguish the Barred Warbler from other members of its genus. A large, bulky warbler, at about 15 cm roughly the size of a Red- backed Shrike Lanius collurio, it presents at first sight an essentially uniform grey appearance as it slips into cover. The adult male is grey-brown above with two narrow pale wing-bars, and whitish or pale grey below, the underparts being barred with dark crescent- shaped marks which extend to the flanks and undertail-coverts, where they are often more pronounced. The barring is less con­ spicuous in autumn and winter, while during the breeding season it varies considerably from one male to another, some individuals being very heavily marked and others showing just suggestions of bars on the flanks and undertail-coverts with the breast almost uniform pale grey. The long tail has white in the outer feathers, particularly at the tips, but this is often difficult to perceive in the field except when the alights or enters a bush, when the tail is fanned. In the female and juvenile the upperparts are browner and the barring less distinct, being absent or nearly so in the majority of juveniles, though again it is often present on the undertail-coverts. The strong legs are dark and the noticeably large bill a dark horn. Adults have staring yellow irides which can be striking at close quarters (see plates 12, 14 and 15). The long, sloping forehead and high, rounded crown also lend the bird a distinctive, powerful and rather aggressive appearance. Young Barred Warblers might be confused with a number of other Sylvia warblers, particularly immature Garden Warblers S. borin and Whitethroats S. communis, but the large size, stout bill

108 {Brit. Birds, 68: 108-114, March 1975] Barred Warbler studies 109 and long tail should be sufficient to preclude any real difficulties in separation provided adequate views are obtained. (See photo­ graph in Limosa, 38: 102, where the stouter bill of this species is obvious in comparison with that of a .) Caution is also required in separating them from grey Hippolais warblers, particularly the large Olive-tree H. olivetorum which also has a long, stout bill. The Barred Warbler is an east European and west Asiatic species. It breeds from about io°E in , between the Baltic states in the north and the Balkans in the south, eastwards between about 56°N and 36CN to north-west Mongolia, just reaching northern Afghanistan (Vaurie 1959). Birds from Turkestan eastwards are paler and greyer and have been assigned to a separate subspecies merzbacheri. In Europe the Barred Warbler has extended its range north-westwards, small populations having become established comparatively recently in south and southern Scandinavia. Indications that it may still be spreading north-west are provided by the first breeding record in the province of Sodermanland in Sweden in 1963 and 1964 at 5g°8'N (Jenning 1965); in June 1972 breeding was confirmed for the first time in Norway, at Molen in Vestfold (Numme et al. 1973), where the species had been an annual summer visitor since 1969. The preferred habitat is thick shrubbery, usually thorny, on commons and meadowland. Damp meadows of willow Salix and ash Fraxinus are also frequented, as well as loose willow plantations interspersed with buckthorn Rhamnus, birch Betula and scattered firs. In parts of Bosnia and Herzegovina habitat consisting of oak Quercus, willow and hawthorn Crataegus is occupied, and in Montenegro shady deciduous forest (Niethammer 1937, Steinfatt 1938, O. Reiser in Melcher 1952). The Barred Warbler is found also in bushy allotments, parkland and overgrown clearings in woods, though it normally avoids extensive forest. In the eastern parts of the range it occurs in mountains up to 2,300 metres above sea level (Dementiev and Gladkov 1968). A notable feature is the species' preference for damp situations, and a great liking is shown for wet meadows and overgrown ditches, while it is also found, some­ times in some numbers, in open, bushy peat bogs. In Poland Gotzman (1965) found that low, thick bushes intertwined with tall grasses were a prerequisite for colonisation by the Barred Warbler, while a moderate weed layer and isolated tall bushes were a preferred addition to the habitat. Within all these habitats the Barred Warbler occurs irregularly and locally scattered, though pairs may occasionally nest only 100 metres or so apart. It is one of the most skulking of its genus and, especially during the breeding season, may easily be overlooked. no Barred Warbler studies Since Barred Warblers prefer to feed in thick cover, perhaps the best clue to their presence is the voice. The remarkably loud, harsh alarm call, once learned, is unmistakable. It is usually uttered from cover, though it is not rare for a bird, when taken by surprise, to emit diis metallic, grating sound from an open perch before darting for cover. The call is best transcribed as 'tcherrr' or 'terrrr', dimini­ shing in speed and often followed by several softer, subdued notes 'tjed, tjed'. A second common utterance used in excitement is a series of short, metallic notes, increasing in pitch and speed as the excite­ ment intensifies and often heard when an intruder reaches the immediate vicinity of the nest. It may be described as a rapid 'ti-ti- ti-ti-titititi'. Melcher (1952) recalled that when he was taking egg measurements the male perched on a nearby cherry tree and uttered this call continuously, while the female crept about in the bushes silent and almost unnoticed. U. A. Corti (quoted by Melcher) found that the churring call was not uttered in the immediate vicinity of the nest, rather that the bird moved to a distance of about 60 metres before calling, while Melcher himself found 20 metres to be the limit. The bird is, however, not always vocal: Rauhe (1956), after a fruitless half-hour search of habitat in Lower Saxony, suddenly heard the alarm churr only when a Fox Vulpes vulpes appeared. There is also a hard 'tcheck', similar to that of other Sylvia warblers. The song is a rather typical Sylvia warbling, perhaps most similar to that of the Garden Warbler and also somewhat like an improved version of the Red-backed Shrike's song (Melcher 1952). It has a rich tone, comparable to that of the Blackcap S, atricapilla (Fry 1970), with rapid short phrases reminiscent of the scratchy phrases of the Whitethroat, and not infrequently the alarm churr is incor­ porated into the whole. Melcher found these single phrases often varied and recorded occasional mimicry, fragments of the song of the Tree Pipit Anthus trivialis being emitted, as well as single calls 'dliii, dliii' with a timbre recalling notes in the song of the Nightingale Luscinia megarhynchos. Although the full song is at times uttered from deep cover, more generally a song-post overlooking the territory is chosen. This may be an exposed perch or the top of a well-foliaged taller tree or bush. From such song-posts the song-flight is conducted. This takes the form of an irregular fluttering flight, twelve metres or so above the ground, which may terminate at the starting point or elsewhere in the territory. Though infrequent, it is rather characteristic and may properly be considered a field mark. At the beginning of the breeding season song is most regular in the early morning and late evening. It generally ceases by mid- or late July. Birds arrive on their breeding grounds in late April and early May, Barred Warbler studies in slightly later in the eastern parts of the range, though arrivals are said to commence in the Moscow area from 18th April (Dementiev and Gladkov 1968). Nest-building takes place between mid-May and early June, the site chosen being normally very well concealed low down in a bush, but sometimes up to 2.5 metres above the ground (Dementiev and Gladkov). Of 20 nests examined by Gotzman (1965) in Poland, 15 were in twigs intertwined with tall sheltering grasses. Ten of these nest sites he studied in greater detail and obtained the following averages: total height of the bush in which the nest was placed, 97 cm (50-200); height of the nest above the ground, 44 cm (20-100); thickness of the branches on which the nest was placed, 13 mm (6-22); length of branches, 41 cm (15-9°)- Both sexes are said to build the nest (Witherby et al. 1938), though the male's share may be limited and the nest lined by the female alone (Melcher). It is a typical Sylvia nest, resembling a large Whitethroat's. An untidy structure, it is made of grass stalks and dried plant stems. On the outside the material is put together loosely and projects in all directions (see plates 14-15). The construction becomes tidier towards the inner cup, which is smooth and even and lined with very fine stalks and hair. The nest studied by Melcher had a cup measuring 8 cm in diameter and 4.2 cm in depth, and a total depth of 7.5 cm. Dementiev and Gladkov gave corres­ ponding average figures of 6-7 cm, 5-6.5 cm and 6.5-7.5 cm respectively. A normal clutch is five, though there may be as few as three or as many as six eggs. Their ground colour is dull greyish-green or greyish-white, blotched irregularly with pale grey and with super­ ficial faint brown speckles which are more profuse towards the blunt end. Eggs with bold red-brown spots, as well as pure white unmarked eggs, have been recorded (Witherby et al.). Eggs are deposited on consecutive days. They are incubated, by both sexes, for 14 days and the fledging period is 14-16 days (Niethammer 1937). A single brood is normal, but two broods have been recorded in Batumi, Georgia (Dementiev and Gladkov). The breeding range of the Red-backed Shrike overlaps that of the Barred Warbler and the nesting association between the two species is well known. A study of this relationship made in Poland by Gotzman (1965) reveals some interesting facts. His observations concerned ten isolated nests of the shrike, nine of the warbler and eleven cases where both species bred in close proximity. Territory sizes measured 0.25-0.40 ha in the former and 0.16-0.30 ha in the latter. In those cases in which the two species bred in close proximity to one another, territories overlapped completely in five instances and partly in two, while there was no overlap in three. 112 Barred Warbler studies This last situation occurred when two pairs were breeding at the edge of two different habitats, and then each species hunted in 'its own' habitat. There were several examples of both species nesting in the same bush complex in more than one year, and alternating breeding also took place in which one species nested in one year and the other in the same bush the following year. Fry (1970) thought it probable that this nesting association conferred some selective advantage on each species which was too slight to be measured. Gotzman mentioned the possibility that a mutual warning against danger might result, though he could not establish any mutual defence of the territory. He concluded that it was highly probable that the association was brought about by a particular composition of the habitat conditions and that no advantage was gained by either species. It is interesting to note, however, that the two species have been seen to associate closely with each other outside the breeding season (Ennion 1955). Though Red-backed Shrikes are generally aggressive towards other birds, Gotzman observed no direct contact between these and Barred Warblers, nor any attempts by either to drive the other away. On the other hand, Melcher (1952) witnessed aggression by a shrike on a number of occasions, especially when the warbler was in its immediate breeding area or visited its favourite lookout post. Pursuits were never sustained by the shrike, whose behaviour was, moreover, inconsistent. Sometimes it ignored the warbler when it used its lookout post, and it would often tolerate the warbler's presence at a distance of only 60 cm. This same Barred Warbler attacked a Goal Tit Parus ater which entered its territory, driving it out from the hedge over open fields, this after the young warblers had left the nest. The principal diet is insects. These are generally obtained from low shrubbery and thick hedges in which the bird moves about stealthily, hopping from twig to twig, carefully searching the whole mass of foliage and tangled undergrowth and picking off its prey. Occasional attempts to catch insects in flight are rarely successful, the Barred Warbler being rather heavy and inept when it comes to twisting and turning sharply. Out of 50 observed instances of feeding, Gotzman (1965) found that 38 (76%) took place in low bushes up to 60 cm high intertwined with grasses, nine were between the thin twigs of taller bushes, and only three in tall grass near the bushes. Schmidt (1964-65) recorded that two pairs breeding along ditches in Hungary sometimes flew just out over the edge of the ditch to find food but usually remained to hunt in the bush and weed zone of the ditch edge. This tendency to feed in well-concealed habitats renders accurate observation extremely difficult, and may explain the paucity of detailed studies. In Russia ants (Formicidae) are Barred Warbler studies "3 commonly taken, as well as larvae of Locusts Locusta migratoria and various insects injurious to trees, and the species is consequently considered beneficial to agriculture (Dementiev and Gladkov). In autumn the birds take a greater variety of foods, including berries and, according to Fry (1970), the flesh of fruits such as pears and apples, as well as earthworms (Lumbricidae) and larvae; even the remains of a small crab (Malacostraca) have been found in the stomach of a British-killed bird (Witherby et al.). It is generally stated that Barred Warblers leave their breeding grounds in mid- to late August and early September (Niethammer 1937, Salomonsen 1953, Dementiev and Gladkov), but observations in west Slovakia by Kaftuscak and Kuban (1969) during the autumns of 1965-67 showed that passage occurred from 26th July to nth September, with the peak in the first half of August. Autumn records on the Continent west of the breeding range are rare, one caught on Vlieland in the Frisian Islands on 30th August 1964 being only the sixth record this century for the Netherlands (Westra 1965), while three at Hesbaye on 4th September in the same year were the first ever for Belgium (Dambiermont et al. 1964). However, this does not apply to Britain, where the species is a regular autumn migrant. During 1958-67 at least 514, almost all juveniles, were recorded, the great majority (83%) on the east coast from Norfolk northwards, particularly in Shetland (Sharrock 1973, 1974). More than three-quarters of these records were between 20th August and 23rd September, and almost half between 27th August and gth September. The migration route in the western part of the range is assumed to be south-eastward. Sharrock concluded from the many data available that British occurrences result from reverse migration. While this is very probable, the recovery of a bird in the province of Barcelona, Spain, on 5th October 1973 which had been ringed as a first-year in Jurmo (59°5o'N, 2i°37'E), Finland, on 16th August 1972 (Fernandez-Cruz 1974) suggests that perhaps a small number of European Barred Warblers do migrate south-west, as postulated by Rudebeck (1956). Accepting that the return northwards in spring takes place along a north-westerly route, it is difficult to understand why there are so few records of Barred Warblers reaching Britain by overshooting in May and June, a point noted by both Sharrock and Davis (1967). Although one might expect at least the birds in the eastern part of the breeding range to winter in India, the entire population of Barred Warblers winters in south Arabia and eastern Africa, mainly from Uganda to Tanzania (Vaurie 1959), inhabiting scrub in the thorny acacia savanna. Indeed, there are only two records from India, both in autumn (Salim Ali and Ripley 1973). ii4 Barred Warbler studies

REFERENCES DAMBIERMONT, J.-L., FOUARGE, J., and DELVAUX, L. 1964. 'Capture d'une Fauvette eperviere (Sylvia nisoria Bechstein)'. Aves, 1: 77-84. DAVIS, P. 1967. 'Migration-seasons of the Sylvia warblers at British bird observa­ tories'. Bird Study, 14: 65-95. DEMENTIEV, G. P., and GLADKOV, N. A. 1968. Birds of the Soviet Union. Israel Program for Scientific Translations, Jerusalem, vol 6. ENNION, E. A. R. 1955. 'Association of Barred Warbler and Red-backed Shrike on passage'. Brit. Birds, 48: 185-186. FERNANDEZ-CRVJZ, M. 1974. 'Recuperation en Barcelona de una Gavilana (Sylvia nisoria) anillada en Finlandia'. Ardeola, 20: 374. FRY, C. H. 1970. 'Barred Warbler'. Birds of the World, 8: 2122-2123. GOTZMAN, J. 1965. 'Die transspezifischen raumlichen Beziehungen zwischen dem Neuntoter (Lanius collurio L.) und der Sperbergrasmiicke [Sylvia nisoria (Bechst,)] in der Brutzeit'. Ekol. Polska, 13A, 1: 1-22. JENNINO, W. 1965. 'Hoksangare (Sylvia nisoria) hackande i Sodertorn'. Vdr Fdgelv., 24: 185. KANUSCAK, P., and KUBAN, V. 1969. 'Einige Bemerkungen zum Herbstzugen der Vogel von Umgebung Piestany'. Zbormk, 15(2): J53-158. MELCHER, R. 1952. 'Brutvorkommen der Sperbergrasmiicke, Sylvia nisoria (Bechst.) im Domleschg (Kt. Graubiinden)'. Orn Beob., 49: 105-116. NIETHAMMER, G. 1937. Handbuch der Deutschen Vogelkunde. Leipzig, vol 1. NUMME, G., SANDVE, J., and THOLLEFSEN, J. 1973. 'Hekkefun av Hauksanger i Norge'. Sterna, 12: 61-64. RAUHE, H. 1956. 'Auffallende Haufung der Sperbergrasmiicke (Sylvia nisoria) zwischen Elb- und Wesermundung'. Om Mitt., 8: 24-27. RUDEBECK, G. 1956. 'Some aspects on bird migration in the western Palaearctic region'. Hanstrom Festschrift (Lund): 257-268. SALIM ALI and RIPLEY, S. D. 1973. Handbook of the Birds of India and Pakistan. Bombay, London and New York, vol 8. SALOMONSEN, F. 1953. Fugletraekket og dels Gdder. Copenhagen. SCHMIDT, E. 1964-65. 'Vogelzonologische Untersuchungen in den Bergen um Buda. III. Nagykovacsi'. Aquila, 71-72: 136-147. SHARROCK, J. T. R. 1973. 'Scarce migrants in Britain and Ireland during 1958-67. Part 9. Aquatic Warbler, Barred Warbler and Red-breasted Flycatcher'. Brit. Birds, 66: 46-64. 1974- Scarce Migrant Birds in Britain and Ireland. Berkhamsted. STEINPATT, O. 1938. 'Nestbeobachtungen bei der Sperbergrasmiicke'. Orn Beob., 35: 122-126. VAURIE, C. 1959. The Birds of the Palearctic Fauna: Passeriformes. London. WESTRA, D. 1965. 'Vangst van een Sperwergrasmus (Sylvia nisoria) op Vlieland'. Limosa, 38: 101-103. WITHERBY, H. F., et at. 1938. The Handbook of British Birds. London, vol 2.

D. A. Christie, 11 Rope Walk, Rye, East Sussex TN31 7NA PLATE 12. Female Barred Warbler Sylvia nisoria at nest, southern Finland, June 1973 (photo: J. B. and S. Bottomley); the habitat is shown on plate 13a. Com• pare this bird with the well-marked males in plates 14 and 15 (pages 108-114) PLATE 13. Breeding habitats of Barred Warblers (page 109). Above, southern Finland, June 1973 {photo: J. B. and S. Bottomley): abandoned, park-like culti• vation, mostly pine, spruce and maple, together with juniper, wild cherry and wild rose; the nest (plate 12) was in the wild currant bush just right of centre. Below, eastern Austria, June 1972 (photo: A. N. H. Peach) (see plates 14a, 15) PLATES 14-15. Male Barred Warblers feeding young, eastern Austria, June 1972 (above and overleaf) and June 1974 (below) (photos: A. N. H. Peach). The nest, of dry grass and plant stems, is very untidy except for a smooth cup (page 111). Note conspicuous arrow-shaped bars on undertail-coverts, often present also on females and juveniles which usually show little barring on rest of underparts