The only European Cetti’s Warbler “Cettia Cetti” occurs in damp, bushy, and waterside habitats across warm temperate latitudes from Southern England and NW Africa to the E Mediterranean, the Black Sea, and Central Asia. European populations are residents, or dispersive but most Asian breeders are migratory, wintering in the Middle East and south to Pakistan.
Polytypic, with three races recognized:
C. c. cetti, (W and S Europe to the W Black Sea coasts; also, North West Africa.)
C. c. orientalis, (Crimea, Turkey and the Levant to the Caucasus and northwest Iran.)
C. c. albiventris. (Central Asia from Caspian Sea east to W China (Xinjiang Uygur Autonomous Region) and south to North Afghanistan.)
A medium-sized nondescript warbler with uniform dark rufous-brown upperparts and well-rounded wings and tail. Its behavior is fundamentally skulking, and it usually betrays its presence by a short burst of distinguishing ‘explosive’ song.
It is quite unlike any other European warbler and the only member of this wide-ranging but primarily Asian genus to occur in the Western Palearctic. Sexes are similar but separable in size, males being much larger than females.
Structure: The nominate race in Europe is similar in body size to Eurasian Reed Warbler but is more robust, with a dumpy body and a proportionately larger head with a distinctly rounded crown and a rather short, fine bill. The wing length of males averages about 10% larger than females. The short and noticeably rounded wings show tightly bunched primaries with no more than five or, occasionally, six tips visible in the wing point.
The first primary is quite long and extends well beyond the primary coverts. The second is relatively short. It has a proportionately long and distinctly rounded tail that is regularly flicked upwards above the back or held slightly cocked, and it is often spread in flight when it appears mostly conspicuous. Together, these characters create the impression of a relatively long-tailed, robust warbler that is enhanced by the short wings and rather short under tail coverts. The legs are quite stout.
That is plain, dark, and nondescript. The nominate form appears particularly dark rufescent-brown, but those breeding in the Middle East and Central Asia are distinctly paler both above and below. European birds have the entire upper parts, including wings and tails. The uniform is dark rufous-brown, offset only by a narrow greyish supercilium and a slightly darker eye-stripe, that contrasts with the crown and ear-coverts, and a broken narrow whitish eye-ring that is most conspicuous below the eye.
The wings show no contrast with the mantle or scapulars. The primaries lack pale tips, making their spacing and projection difficult to discern in the field. The underparts are drab, unmarked, and likewise featureless, although the chin and throat are white with a slight greyish wash and the belly is pale greyish white.
Below the throat, the breast, and upper flanks darken to brownish grey, then darken further to dull rufescent-brown or sepia-brown on the lower flanks. The undertail coverts are drab grey-brown, colder than the flanks, and narrowly tipped pale grey.
The juvenile birds do not differ meaningfully from adults and are often inseparable after the first autumn moult is completed. The bill is dark grey with a dull pink lower mandible that usually darkens slightly at the sides towards the tip. The legs and feet are brownish-pink during the breeding season but slightly paler and without the brown tone throughout the rest of the year, although this coloring may refer to immature birds.
Unlikely to be confused with any other species in Europe, where no other warbler shares the combination of dark rufous-brown upperparts, drab brownish to greyish underparts, and pale grey tips to the grey-brown under tail-coverts. This appearance, together with the long, broad tail and combined with its characteristic and readily recognizable song makes confusion most unlikely.
Within its Asian range, the paler appearance of the races orientalis and, chiefly, albiventris approaches that of several similarly-sized unstreaked Acrocephalus and Locustella species. Even though closer in overall appearance, no species in either genus shares a similar head and body profile, and the wing structure with the long first primary. All races throughout the range have the characteristic explosive song.
The daytime song is a loud series of clearly defined notes that starts and finishes abruptly and lasts between 2 to 5 seconds. In delivery and quality, it is quite unlike that of any other European bird. There is considerable individual and regional variation, but each bird gives a stereotyped song. That seems to keep for life, and which is individually recognizable.
The Cetti’s Warbler song commences with an introductory explosive ‘tchi’ or ‘chuit’ that is followed immediately by a rapid series of ‘chuee’ or ‘piti’ notes, habitually between 6 and 15. In Southern England, the typical song is variously described as ‘chuit chuee-chuee-chuee-chuee-chuee’, or ‘chee chewee-chewee-chewee-chewee’, or ‘chee cheweechoo-weechooweechoo-wee’ or similar variations, within a frequency range of 3–8kHz.
In southern France, a slightly different song is given as ‘ti tipitipitpi ti-pi ti-pi’, with a slight pause between the main song and the last two notes, which are sometimes repeated a second time. The main song may be followed by a series of ‘chip’ calls. During peak song periods, particularly at dawn, males normally deliver 1 to 2 songs per minute as they move around the territory.
Therefore, the interval of 1 to 4 minutes or longer is typical at other times. Territorial males also have a nocturnal song that starts in the early hours and continues until dawn. It is delivered from a fixed song perch and with greater frequency than the daytime song.
This song is briefer and less varied and rich than a daytime song, described as ‘pwit pit-i-chew-it-chew-it’. It elicits no response from other males and is thought to advertise the territory to unmated females. It is given in England by both single and mated males.
In autumn and winter, a quieter less energetic sub-song is given with reduced frequency. In the Caucasus and Central Asia, the songs of orientalis and albiventris differ slightly from that of nominating cetti in Western Europe but they are similar in structure and delivery and remain easily recognizable. The usual contact call, given by both sexes, is a staccato ‘chip’ or ‘tschiek’, usually given singly, but sometimes strung together in a series.
This lacks the whiplash quality of the similar calls of Savi’s and River Warblers. In addition, the female occasionally gives a quiet ‘huit’ or ‘wheet’ in presence of the male. A loud clicking or ticking ‘tsuk-tsuk-tsuk’ is given in alarm and also a rattling call described as ‘t-k-t-k-t-k-t-k’, like the winding of a mechanical clock. Another rattle-like call, like that of a Northern Wren but slower and slightly higher-pitched, can be heard throughout the year. Also, a ‘tichich- ich-ich’ call from alarmed birds.
In Europe, adults have a complete post-breeding moult. This takes place from mid-June in Southern Europe, but from mid-July or later in Northwestern Europe. Wing feather replacement follows the typical passerine sequence, but the tail feathers may be dropped and replaced simultaneously.
Individual duration is approximately 60 days, so moult is complete from mid-August in southern populations but not until early to mid-September in NW Europe. Many birds undergo a partial pre-breeding moult in March and April. The extent of this is variable but it usually involves the head and body feathering and some wing-coverts and occasionally some tail feathers and tertials.
In South West Europe, post-juvenile moult occurs between late June and September and is extensive, involving the head and body feathers, lesser and median coverts, inner greater coverts, and some tertials. Occasionally, all the greater coverts and a variable number of inner primaries and secondaries are also replaced. In NW Europe, the extent of post-juvenile moult is less clear-cut.
Some young birds, perhaps from early broods, also replace all the body feathering between mid-July and mid-September. Others, however, appear to develop their first-winter body and head plumage by adding to, rather than replacing, the juvenile feathering, also between mid-July and mid-September. Moult in the eastern races, orientalis and albiventris, is poorly understood.
The orientalis, which is a resident or a short-distance migrant in the Middle East, has a complete post-breeding moult, although said not to have begun by mid-August when adults are still feeding young and the plumage is heavily abraded. This is followed by a partial pre-breeding body moult.
For example, birds examined at Kumbashi, on the Caspian Sea coast of Azerbaijan, were said to have a ‘vigorous’ partial moult between mid-March and early April. The Central Asian race “albiventris” has also been reported to have a complete moult after breeding. In E Kazakhstan, however, adults are still in old plumage in September and October and presumably moult in the winter quarters after migration.
In Western and Southern Europe, the bird breeds in a wide variety of damp habitats, including swamps, marshes, reedbeds, watercourses, and lake margins, and always requires low, thick scrub and bushes nearby. It usually breeds close to the water but peripheral or overspill populations will use adjacent habitats such as damp woodland, hedgerows, dry scrub, cereal fields, and dry reeds.
The territories may include wet reedbeds, but patches of scrub or bushes are required to provide areas for foraging. Stands of pure Phragmites over water are usually avoided. It is most frequent in the warmer regions around the Mediterranean, breeding from sea level up to 1,450m in Spain and as high as 2,100m in the Haut Atlas, Morocco.
The eastern races orientalis and albiventris are less restricted to wetlands than their European counterparts. In Central Asia, it breeds most frequently in meadows with scattered bushes, hedgerows, orchards, dense scrub, and herbage. It is not rare in arid semi-deserts with scattered low scrub provided there is a damp watercourse or irrigation channel nearby.
Also, the breeding takes place along mountain streams in the hills above Samarkand to at least 1,550m, while in Kazakhstan it breeds in the lower Tien Shan Mountains to at least 750m. Migrants are not restricted to wetlands and can occur in most habitats up to 1,200m.
A classic skulking species that is difficult to observe well, although it is not particularly shy. It usually forages within thick cover near the water’s edge, collecting small insects and aquatic invertebrates on or near the ground and gleaning prey from leaves, twigs, and branches. Also, it extracts insects from broken reed stems.
It feeds in the open area occasionally, predominantly in winter, hopping about on mud or vegetation. When disturbed near the nest, it adopts an alarm posture with head lowered, tail cocked, and wings drooped along the flanks and flicked nervously.
It often gives a short alarm call or burst of the song before flying to a more distant perch and singing again. Males occupy large territories and tend to sing throughout the year except during moult and during cold spells in winter. Territories are often linear, following streams or other watercourses, with singing birds about 50–100m apart in favored areas.
In Kazakhstan, they are more widely spaced, up to 500m apart. Territories are defended vigorously, and rival males may be attacked and expelled if song fails to deter them. In extreme cases, intruding males are vigorously pursued in flight low over reeds and scrub and such chases may last for several minutes.
The song is rarely heard during mid-winter but its frequency increases from late winter and peaks during the early breeding season. It is most frequent in England from late March to May, when it can be heard throughout the day, but especially at and after dawn and at dusk.
It is delivered from regularly used song posts (often 100–250m apart) as the bird moves around its territory, typically with a long pause between each burst. The singing bird frequently sits upright with head thrown back and tail slightly lowered. Breeding males produce a nocturnal song, during which they give more frequent bursts from the same song post. They often begin this in the early morning hours but revert to the daytime songs at dawn.
Some males are monogamous, but the majority are polygynous. Of 125 territorial males in a study in Southern England, just 22 were monogamous, while 70 were polygamous, the remainder remaining unmated or with status unknown. Of the polygynous males, 42 attracted two females, 22 attracted three, and six were mated with four.
The pair-bond is never strong, the male associating little with the female, yet the same bond is often renewed in successive years. Males take little or no part in nest building, incubation, or raising the young. When the first female starts incubation, the male continues to attract additional females.
Within the male’s large territory, females appear to establish smaller, discrete breeding territories and will defend these against other females mated with the same male. In Western Europe, nest building starts in May. Normally, the eggs are laid from early June but mostly during mid to late June.
The nest is built by the female alone, usually with the male in close attendance and singing regularly. It is placed in thick vegetation close to water, typically 0.3–0.45m above ground, habitually supported by stems of reed Phragmites or nettle Urtica, or by smaller twigs of tangled scrub.
It is an untidy construction of leaves and stems, lined with feathers, hair, and other fine material. The usual clutch is 4–5 eggs. Incubation by the female lasts 16–17 days. Fledging takes a further 14–16 days, the young being fed by both parents. After fledging, males accompany females and young within the breeding territory for about 15–20 days until they disperse.
Females are usually single-brooded. Some may raise a second brood, but this tends to be less successful than the first. The breeding behavior of orientalis and albiventris is not known to differ from the nominate race. In Kazakhstan, albiventris begins singing on its return to breeding sites from late March onwards.
It is describing the nest of albiventris as built from grass and leaves and lined with thin grass and occasionally hair. A clutch of 4–5 eggs is laid from May to early June. Singing ceases in late July to mid-August.
Breeds throughout the warmer regions of Western and Southern Europe to Central Asia. Most in North Africa and Europe are resident or dispersive but those breeding in the colder regions of western and Central Asia migrate to warmer regions outside the breeding season.
c. cetti: The nominate race is largely resident in the lowlands of North Africa in Morocco, Algeria, and Tunisia and throughout the northern Mediterranean from Portugal and Spain east through Italy and the Balkans to Greece. Warmer winters in northwest Europe in the late 20th century have enabled expansion into this formerly inhospitable region.
However, it remains largely absent from the Black Sea coast, where freezing winter temperatures in Bulgaria and Romania prevent settlement in this otherwise suitable region.
It is reported to breed in the Crimean region of Ukraine, but it is said to be a summer visitor, arriving in the second half of April. The northern breeding limit in France during the 19th century lay in “Pyrénées Atlantiques” and Provence. Slow expansion to the north, west, and southeast began early in the 20th century.
It has afterward continued into most suitable low-lying regions of southern, western, and northern France. A secondary expansion through South-Eastern France reached Switzerland, where breeding occurred annually. Breeding was first established in Belgium in 1964 and in Germany in 1975, but the colder winters of northern continental Europe have prevented permanent colonization.
Birds reached the Southern Netherlands during the 1970s and numbers increased to a peak of approximately 60 singing males/ But they declined sharply after a severe winter in 1978 and although breeding continued to 1983, the species became rare, with just 49 records from the country from 1986 to 2001 and no succeeding sign of recolonization. The first record from Jersey in the Channel Islands in October 1960 was followed by three singing males in November 1967, but breeding was not established until 1973.
The colonization of Southern England followed a similar pattern, with the first record in Hampshire in March–April 1961, followed by another in East Sussex in October 1962. The first singing male was in 1967, followed by a series of scattered singing birds from 1971 onwards and confirmed breeding in the Stour Valley in Kent, in 1973.
A succession of mainly mild winters then allowed continued expansion, with only occasional setbacks. The population increased rapidly in England and S Wales in the early years of the twenty-first century, from nearly 700 pairs of singing males in 2000 to over 1,300 by 2005.
It is mostly concentrated within the warmer southern coastal counties, although East Anglia now holds a substantial population and the limit of regular breeding extends north to Anglesey in N Wales. Small numbers also occur in inland counties north to C England.
c. orientalis: – This larger paler form breeds in W Asia. The western limit lies in Turkey, but birds showing characters of orientalis breed in Lesvos, Greece, and apparent intergrades with the nominate form have been reported further west. The breeding range follows the southern coast of the Black Sea and extends into the lower slopes of the Caucasus Mountains in Azerbaijan, South Georgia and Armenia up to 1,900m.
The only orientalis appear to breed in the Caucasus. However, it is unclear whether it extends north and east into S Russia or whether birds breeding along the Terek and Volga Rivers are albiventris. That includes the entire Caspian region within the range of orientalis and extends its range east across North Kazakhstan through the Astana region to Rozhdestvenka (c. 77°E).
Moreover, in the south of the Caucasus and the Caspian Sea, orientalis breed in Cyprus, Syria, Lebanon, and northern Israel, then east through Jordan, Iraq, and northern Iran, and along the Amu Darya through southernmost Uzbekistan and neighboring parts of Turkmenistan. It appears that orientalis is either resident or a short-distance migrant within the Middle East.
This is not amazing as the climate in this region is mild throughout the year and only birds breeding at higher elevations in the Taurus and Caucasus Mountains, and in North Kazakhstan and adjacent regions of Russia vacate the breeding areas. Some descend to lower elevations while others migrate to winter in the Middle East.
In Turkey, birds descend from the Taurus Mountains to winter in the south and west of the country and birds breeding in the Caucasus descend to the foothills by November, returning as the snow line recedes, though it is scarce, or overlooked, in Armenia during the winter months.
c. albiventris Breeding. Well, as a breeding bird, this race occurs in Uzbekistan, S and E Kazakhstan, and westernmost China. With the advent of irrigation in the twentieth century, it has spread into formerly unsuitable arid regions in Central Asia.
Where it requires little more than a water-filled channel and a few overhanging bushes. The ranges of orientalis and albiventris now approach and may possibly overlap in Turkmenistan and Uzbekistan in the region of the Aral Sea and the Amu Darya.
They extended the western limit of albiventris to include the Terek River where it enters the Caspian Sea and comment that it is common in the delta of the Volga River and along the Ural River to Orenburg and Orsk. Elsewhere, the breeding range of albiventris includes much of Southern and Central Kazakhstan, from the northern end of the Aral Sea, along the length of the Syr Darya and into Uzbekistan.
Also, the south to the region of Samarkand, where it is numerous in the wetlands surrounding the city and along tree-lined streams in the surrounding hills up to at least 1,550m. In Kazakhstan, it is particularly common in wetlands along the southern edge of Lake Balkash, in the Alakol Depression, and along the Ili River, and is widespread around Almaty, including the lower slopes of the eastern Tien Shan.
To the east and north, breeding extends to the Zaysan Depression, the region of Kamenogorsk , and the foothills of the southern Altai. In China, it breeds in suitable wetlands in the extreme west of the Xinjiang Uygur Autonomous Region, along the southern foothills of the Tien Shan, and in wetlands and along rivers in the Takla Makan Desert, including the Kashi region. It is common along the Ili River and in the foothills of the Altai Mountains.
Non-breeding: This race is mainly migratory, but some southern breeders remain on or close to the breeding areas throughout the year. Small numbers regularly winter north to the upper Amu Darya and are more often noted in southernmost Kazakhstan, east to Almaty, now that milder winters have become more frequent.
It’s winters widely in Southern Iran and Southern Afghanistan and is scarce and local from October onwards in the lowlands of Pakistan, where wintering is centered on Baluchistan and the Northwest Frontier Province, some birds reaching the Indus plain in the Punjab and Sind Province. It has been recorded as a vagrant in northwest India, with scattered records south and east to Bharatpur in Rajasthan.
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The West European population is largely resident, but post-breeding dispersal occurs during September and early October, both north and south from the breeding areas. Birds are more widespread in the Mediterranean region during the winter months.
There is limited evidence of migration along the Atlantic coast of France in late August and early September but no indication that European birds reach North Africa, where increased numbers wintering in the lowlands are believed to originate from local breeding populations in the Atlas Mountains.
Ringing recoveries in northwest Europe show that northerly dispersal involves juvenile birds almost entirely, with reported movements from Belgium to the Netherlands and E England, and from the Channel Islands to Southern England. The occurrence of vagrants, for example at Cape Clear in Southern Ireland, over 600km northwest of the nearest breeding area, demonstrates that longer-distance dispersal is possible. Elsewhere in Europe, vagrants have been recorded from Scotland, Sweden, and Poland.
The situation is less clear in Southeast Europe. Part of this population migrates to winter outside the breeding range, in the Middle East. The passage occurs across the Southern Aegean Sea where the species is a regular prey item of Eleonora’s Falcon. The origin of these birds is unidentified since European birds are believed to be largely resident. But they could be from the Black Sea, or from colder regions of Turkey.
In Israel, dispersing birds appear from September onwards, but the main passage is in October and November when migrants of both Orientalis and the nominate race augment the local population. Wintering birds remain until late February. Return passage through Eilat shows two peaks, one in late February and early March, the second in late April and early May, suggesting that two populations pass through.
Moreover, two sight records of vagrants in Egypt are probably referable to Orientalis. Small numbers showing the characters of albiventris have been trapped on migration and during winter in Israel, particularly at Eilat. Little is known of movements within C Asia, where albiventris is almost entirely migratory.
It leaves the Orenburg region in late August, but some linger in the Volga delta until November. To the east, departure occurs between the end of September and late November. Migrants pass through the Syr Darya region from mid-September with some still present to mid-November, but all move when ice forms on the lakes.
The first birds return to breeding sites in mid-March when these are still under a covering of ice and snow, but southern breeders arrive in numbers by early April. Northern birds breeding near Orenburg (presumably orientalis) do not appear until mid-May.
c. cetti Plumage – Adult fresh forehead to nape plain dark rufous-brown. Supercilium dull greyish white to ash-grey, quite short and narrow, appearing broadest and most contrasting between the bill base and the eye. It is less distinct behind the eye, tapering and merging with the side of the crown before the rear of the ear-coverts. The Loral spot variable is usually restricted to a dark brown spot in front of the eye but sometimes extending to the bill base to form a complete loral line.
A dull rufous-brown eye-line is well defined immediately behind the eye but diffuses into the upper ear-coverts and rear of supercilium. Ear-coverts pale greyish white to ash-grey, with narrow rufous-brown tips creating indistinct mottling, particularly towards the upper edges. Eye-ring narrow, greyish white above the eye, merging with supercilium; whiter below the eye, usually contrasting slightly with the grey ear-coverts.
Mantle and scapulars dark rufous-brown and unmarked, concolorous with a crown. Rump and upper tail-coverts like mantle but usually slightly brighter. Tail dark brown with broad, diffuse rufous-brown fringes, slightly darker than the upper tail-coverts. Chin and throat white with a faint greyish wash. Sides of throat slightly greyer, merging with lower ear-coverts.
Also, the breast is white, washed light brownish grey, becoming darker ash-grey towards the sides, often linked to a greyish half collar on the lower sides of the neck. Upper flanks with a light brownish-grey wash, darkening to dull sepia-brown on the lower flanks. Undertail-coverts dull, cold sepia-brown with narrow greyish white tips.
The belly is paler than breast and flanks, naturally white with a pale greyish or creamy wash. The lesser, median, and primary coverts dark rufous-brown, lacking darker centers. Greater coverts and tertials with broad, dark rufous-brown fringes, like the mantle cooler. Secondaries and primaries blackish brown, narrowly edged dark rufous-brown.
Primary tips dull rufous-brown, lacking contrast with the blackish-brown webs. Alula with a broad, diffuse, dull rufous-brown fringe and a slightly darker center. Underwing-coverts light grey-brown.
Adult Worn: – It is likely freshly moulted bird but individually variable. Supercilium is sometimes reduced to a narrow, pale greyish line from the bill base, fading rapidly behind the eye. Upper parts are slightly drabber, dull rufous-brown to dull greyish brown, particularly on the crown and nape; the more rufous rump and upper tail-coverts become slightly more contrasting.
Further, the chin, throat, and belly are usually whiter, and breasts and flanks paler. Sepia-brown under tail-coverts may lose pale tips. Webs of rectrices and flight feather browner. First-winter as a fresh adult but with slightly browner rectrices and flight feathers.
Juvenile: – the young differ from a fresh adult by more uniform appearance to head, which lacks distinct supercilium but shows conspicuous pale eye-ring. Upper parts are often duller and slightly less rufous. Webs of rectrices and flight feathers dark brown, less blackish. Underparts slightly colder, more extensively washed ash-grey and flanks often paler and browner, lacking grey tones.
Bare parts: – The upper mandible is dark grey-brown to dull plumbeous-grey. Lower mandible dull pink to pinkish-yellow at the base, becoming dark bluish grey towards the tip. Tarsi pale pink, pinkish flesh, or pinkish brown; toes sometimes slightly browner feet; soles dusky yellow to pale flesh. Iris dull sepia-brown to blackish brown in adults; dull gray-brown to dark brown in immature birds.
Other races: – Similar in structure to nominate cetti.
Recognition: – A stocky Cettia with rich, rufescent-brown upperparts, grey-tinged underparts, and pinkish legs. Readily distinguished from all other European warblers by the rounded wing with large p1 and short p2, and by ten (not 12) rectrices.
Aging: – In late summer, adults show worn primaries and tail feathers and are readily separable from juveniles in fresh, unworn plumage. In Southern Western Europe, from September onwards, young birds are partially moulted and show a moult limit in the greater coverts between newer inner and older outer feathers. Also, and sometimes a contrast between newer inner and older outer primaries.
They are thus distinguishable from adults in which the entire plumage is freshly moulted. In northwest Europe, birds in wing moult in early autumn are adults. From mid-August onwards, separation of moulted adults and juveniles becomes difficult. Adults show fresh darker flight feathers and tail feathers, the latter with broad tips. In young birds, these are unmoulted and slightly browner and paler.
The tail feathers are less broad than in adults, usually with slightly worn tips. These differences are slight and only useful with experience, and some birds cannot be reliably aged. Palate color appears to provide a useful character, being yellow in young birds and pale pink in adults. Otherwise, skull ossification provides a reliable means of aging until October at least.
Clinal, with smaller darker birds’ resident in Western Europe and larger paler birds breeding in Central Asia. There is considerable intergradation in the populations of E Europe and Western Asia and racial boundaries are not well established. Only the most distinctive western and eastern birds are racially identifiable with certainty.
c. cetti (Western and Southern Europe to the Western Black Sea coasts; also, North West Africa) Described above. The darkest and smallest form. Some birds from northwest Africa and the Balearic Islands are almost as pale as Orientalis, while others from the Balkans, Crete, and Turkey resemble the nominate form but overlap with the larger Orientalis on measurements.
c. orientalis (Crimea, Southern Russia, Turkey, Cyprus, and the Levant to the Caucasus and NW Iran) Distinctly larger and paler than the nominate race, with a longer, paler, and better-marked supercilium that tapers and merges with the crown towards the rear of the ear-coverts. Entire upper parts, including crown, mantle, upper tail-coverts, tail, wing covert, and tertial fringes warmer and paler rufous-brown than nominate.
While the chestnut-brown edges to primaries and secondaries create a warm panel in the closed wing that contrasts with the upper parts. Underparts are paler than nominate with a white center to the belly and lower breast and only a light greyish wash on the sides of the neck and breast and along flanks, becoming pale greyish-brown towards the central region. Undertail-coverts pale grey-brown, the tips to the longest feathers being slightly broader and paler than in the nominate race.
c. albiventris (S Russia and Central Asia east to Western China) Slightly larger but strikingly paler than orientalis. Supercilium paler and greyer than in nominate race and usually distinct to the rear the of the ear-coverts. Upper parts, including edges to the closed wing feathers, light tan, paler than in orientalis, and lacking the darker rufous and chestnut tones; considerably paler than in the nominate race.
Also, the sides of the neck and breast lightly washed pale grey, merging with the similarly colored ear-coverts. Underparts cleaner and paler than the other races, with the chin, throat, breast, belly, and flanks uniformly washed with a delicate pale grey. Ventral region pales brown, wrapping around from the upper tail-coverts. Undertail-coverts whitish with a faint brown tinge and broader (but less contrasting) white tips.
Taxonomy and Systematics:
Birds breeding in W and C Turkey appears intermediate between the nominate form and orientalis and has been described as sericea. But differences from the nominate form appear slight, variable, and inconsistent. Here we treat sericea as a synonym of C. c. cetti.