[group] Old World warblers | [order] PASSERIFORMES | [family] Phylloscopidae | [latin] Phylloscopus trochilus | [UK] Willow Warbler | [FR] Pouillot fitis | [DE] Fitis | [ES] Mosquitero de los Sauces | [NL] Fitis | [IRL] Ceolaire sailí
Measurements
spanwidth min.: 16 cm
spanwidth max.: 22 cm
size min.: 11 cm
size max.: 13 cm
Breeding
incubation min.: 12 days
incubation max.: 14 days
fledging min.: 11 days
fledging max.: 14 days
broods 1
eggs min.: 4
eggs max.: 8
Status: A common summer visitor from April to September.
Conservation Concern: Green-listed in Ireland. The European population is considered to be Secure.
Identification: Very similar to Chiffchaff and about the same size as that species. Ages and sexes appear largely the same. Pale green above, with a thin yellow supercilium and dark eyestripe. The undersides are lemon-yellow, some juveniles being darker yellow in autumn. The legs pink, though some may legs as dark as those of Chiffchaff. In comparison to Chiffchaff, note the paler undersides, brighter upperparts and the call/song.
Similar Species: Other Warblers - Chiffchaff, Wood Warbler.
Call: A soft “hu-it” similar to that of the Chiffchaff. The song differs markedly from that of the Chiffchaff and is the easiest way of separating these similar species. It is a very pleasing, descending series of notes, which is frequently repeated.
Diet: Feeds almost exclusively on insects and other invertebrates.
Breeding: One of the commonest breeding birds in Ireland (about 1 million pairs), with the highest densities in stands of willows along the edges of bogs and marshes. Less frequently in hedgerows, forests and well-vegetated gardens.
Wintering: Willow Warblers winter in central and southern Africa. There are no winter records of Willow Warblers in Ireland.
Where to See: Common throughout Ireland.
Physical characteristics
Small, slight, graceful warbler, light on the wing and active in cover. Epitome of Phylloscopus, particularly of small species which lack wing-bars and striking supercilium. Plumage usually quite pale and bright, with essentially olive upperparts and yillow-white underparts, yellow-white supercilium, and yellow-brown legs. Song distinctive. Sexes similar, no marked seasonal variation.
Habitat
Breeds in west Palearctic in middle and upper latitudes within temperate and boreal climatic zones, continental and oceanic. Differs in being a bird less of mature woodland than of scrub, second growth, and transitions to more open habitats. Unlike P. collybita, will readily settle on shrubby, bushy, to cleared ground starting regrowth, even in absence of trees. Thus attracted to fringe areas such as birches beyond arctic taiga, heath lands, or forest clearings.
Other details
Phylloscopus trochilus is a widespread summer visitor to much of Europe (except the south), which accounts for less than half of its global breeding range. Its European breeding population is extremely large (>56,000,000 pairs), and was stable between 1970-1990. Although there were declines in a number of countries?notably Sweden and Finland?during 1990-2000, populations were stable in Russia and across much of central and eastern Europe, and the species underwent only a small decline overall.
Feeding
Insects and spiders, in autumn also berries. Food obtained mostly by picking from leaves, twigs, and branches, also flycatching
Breeding
Breeds mid April to mid June in Central and West Europe, May-July in Finland, May to mid July in North-West European Russia. Nest site is built on ground, well concealed in vegetation, including herbs, bases of low shrubs and trees, and grass tussocks. Nest is a domed structure of dry grass, leaves, stems, moss, lichen, twigs, conifer needles, bark fibre, often with rootlets and pieces of rotten wood, lined with finer grasses, rootlets, andimal hair, and feathers. 4-8 eggs are laid, incubation, 12-14 days, by female only.
Migration
All populations migratory, wintering extensively in sub-Saharan Africa from southern Senegal east to Ethiopia, south to South Africa. From extreme east of breeding range, route thus exceptionally long at least 12 000 km. Within Europe, birds from west of range head south to south-west in autumn- north Scandinavian and Finnish birds head south to south-east, indicating migratory divide in border area. Spring passage apparently on broader front, with recoveries of ringed birds averaging further east than in autumn. Afrotropical recoveries show that birds from west and central Europe, including Norway and southern Sweden, winter mainly in West Africa, birds from northern Scandinavia and Finland winter in central, East, and southern Africa. Migration earlier in autumn and later in spring than in Chiffchaff. Southward movement begins late July, and passage through Europe and across Mediterranean mostly completed by end of September. Reaches northern parts of African winter quarters in September, South Africa mostly from mid-October. Spring migration begins late February to March. Passage through Mediterranean mid-March to mid- or late May, chiefly April, averaging later in east than west. First arrivals in Britain late March, main arrival in April. Central European breeding grounds also re-occupied at end of March and in April. Main arrival in southern and central Sweden 21 April to 15 May, northern Sweden 11-25 May. At Lake Ladoga (north-west Russia), most local birds arrive by 15-20 May, passage continuing to early or mid-June.
