Moltoni's Warbler Curruca subalpina Scientific name definitions

12 cm. Small warbler with rather short, square-ended tail and moderately pointed wings. Male breeding has head and upperparts blue-grey with very faint tinge of buff-brown; remiges blackish with broad buffish grey to dull greyish-white edges, tertials narrowly but distinctly edged and fringed with pale brownish to greyish white, upperwing-coverts greyish black with broad greyish fringes, alula centred blackish grey with whitish fringe; tail very dark grey-brown or blackish, outer rectrix with edge of outer web and tip of inner web whitish (variable, white sometimes more extensive), adjacent pair whitish-tipped and with white wedge on inner web, next pair with narrow whitish at tip; chin, throat and much of underparts salmon-pink, accentuated by rather narrow but conspicuous white submoustachial stripe, pink becoming paler and less bright on flanks, with belly and undertail-coverts white; iris deep orange, eyering pinkish; bill light pinkish, with grey culmen and tip; legs orange to light reddish. Male non-breeding has crown and upperparts duller, with brownish tinge, edges of flight-feathers more brownish buff, and salmon-pink colour of underside largely concealed by broad whitish tips of feathers. Female breeding is very like non-breeding male, but with head pale greyish brown, ear-coverts usually slightly darker, upperside, including wings and tail, browner or with buffy-olive cast, underside mostly very pale buffy brown, whiter on throat and submoustachial region, duller bare parts; non-breeding female very similar, but browner above and whitish and less deeply coloured below. Juvenile is like non-breeding female, but more grey-tinged brownish buff above and on head, with darker wings and tail, latter with less white, and more uniformly light buffish below, iris dark olive-brown, orbital ring dull yellow-brown; first-winter of both sexes much as non-breeding female, bare parts largely as juvenile.

Often referred to by (sub)species epithet moltonii, but name subalpina is valid and has priority (1 Baccetti, N., Massa, B. and Violani, C. (2007). Proposed synonymy of Sylvia cantillans moltonii Orlando, 1937, with Sylvia cantillans subalpina Temminck, 1820. Bull. Brit. Orn. Club 127(2): 107–110. Close , 2 Svensson, L. (2013). A taxonomic revision of the Subalpine Warbler Sylvia cantillans. Bulletin of the British Ornithologists’ Club 133(3):240–248. Close ). For long treated as a race of C. cantillans, but recognized as being distinct on account of call, moult strategy, delayed breeding season, and very divergent mtDNA; also, more recently, the two found to occur sympatrically in N Italy (3 Brambilla, M., A. Quaglierini, F. Reginato, S. Vitulano, and F. Guidali (2008). Syntopic taxa in the Sylvia cantillans species complex. Acta Ornithologica 43(2):217–220. Close ). Monotypic.

Breeds in maquis of all kinds, especially that dominated by strawberry tree (Arbutus) and areas of tree-heath (Erica), also in maquis with holm oak (Quercus ilex) and in high maquis beneath maritime pine forest. Habitat much as that of C. cantillans. From sea-level to c. 1000 m. On non-breeding grounds, found frequently in acacia (Acacia) savanna or bush, in tamarisk (Tamarix) thickets along wadis and watercourses, and in bushy areas at desert fringes and oases; occurs commonly also in coastal mangroves and in bushy areas bordering reedbeds (6 Zwarts, L., J. van der Kamp, E. Klop, M. Sikkema, and E. Wymenga (2014). West African mangroves harbour millions of wintering European warblers. Ardea 102(2):121–130. Close ). See also C. cantillans.

Long-distance migrant. Leaves breeding grounds from late Jul to Sept, with autumn passage in breeding range until Oct, reaching non-breeding grounds in sub-Saharan Africa from mid Aug, but not common until Nov. Presumed wintering range is in W Sahel, as recorded in N Nigeria and N Cameroon and on migration in S Algeria; winter range probably extends from S Mauritania and Senegambia E at least to N Nigeria and Niger. This species returns late to its breeding grounds, reaching breeding areas mid Apr to mid May, c. 2–3 weeks later than C. cantillans populations breeding at similar latitudes; this thought to be due to the fact that, unlike C. cantillans, it undergoes an extensive pre-breeding moult in late winter in Africa. Vagrant N to British Isles.

Diet and foraging behaviour not known to differ much from those of C. cantillans, which see. Feeds mostly on small invertebrates and their larvae; outside breeding season, and especially preceding the autumn migration, eats berries and small fruits, too. Takes grass seeds and nectar on occasion. Forages on higher and outer parts of bushes and small trees at medium height (c. 1·5–3 m), less frequently higher in tree canopies and in inner and lower parts of vegetation; rarely on ground, but more frequently so during migration. Generally found singly, occasionally in twos; will form small flocks on passage and at favoured feeding sites in winter.

Song , given usually from bush or in flight, a fairly protracted, rather hurried, somewhat scratchy warbling of up to 3 seconds or so in duration, consisting of high-pitched whistles and buzzing call-like notes, the whole sometimes not too unlike the song of European Serin (Serinus serinus); to experienced ears somewhat faster and slightly higher-pitched, and more insect-like, than song of C. cantillans. Call distinctive, a short metallic or buzzing trill, “trrrt” or “zerrr”, recalling Northern Wren (Troglodytes troglodytes) and reminiscent also of common call of C. conspicillata but less sustained and shorter; differs clearly from calls of C. cantillans.

Season mainly May–Jun, with most clutches laid mid May; apparently usually one brood. Monogamous; solitary, territorial breeder. Male performs song flight in which he makes fast ascent to several metres followed by slow fluttering descent while singing. Male builds unlined “cock nests”; breeding nest constructed by both sexes, a deep, sturdy cup of grasses, thin roots and leaves, lined with finer grasses, rootlets and hair, placed up to 130 cm above ground in low scrub, bush or small tree. Clutch mostly 3–5 eggs , means 3·7 in Corsica and 4·5 in SE France; incubation by both sexes, period 11–12 days; chicks fed by both sexes, nestling period c. 10–12 days; fledglings attended by both parents.

Not globally threatened (Least Concern). Appears to be not uncommon within most of its breeding range; common in Corsica. Breeding density in Corsica varies with habitat, up to 4·2 pairs per 10 ha in medium-height maquis but 1·5 pairs per 10 ha in heterogeneous maquis (7 Thibault, J. C., and G. Bonacorssi (1999). The Birds of Corsica: An Annotated Checklist. British Ornithologists’ Union Checklist 17. British Ornithologists’ Union and British Ornithologists’ Club, Tring, UK. Close ). Little information from non-breeding range but, as with C. cantillans, increased irrigation and tree-planting in Saharan oases may have favoured the use of these areas in recent times. No evidence of any significant decrease in this species’ numbers in recent decades, and it may even have increased in some parts of its range.