All species › Passerines › New World warblers › Chestnut-sided Warbler
Chestnut-sided Warbler | Setophaga pensylvanica
Roestflankzanger | Reinita de Pensilvania | Mariquita-de-flanco-castanho
The Chestnut-sided Warbler breeds in young deciduous woods and clearings in eastern North America and winters mainly from southern Mexico to Panama. The guide area lies on the southern edge of its winter range; it occurs here in small numbers, mainly in north-western Colombia. In non-breeding plumage it often holds its tail cocked and its wings slightly drooped.
Voice
The call is a fairly low, sharp chip. The song is a short, clear series of whistled notes ending with an accent, roughly weet-weet-weet-wee-CHEW; in the guide area heard at most in spring.
Recording: Mario Reyes Jr — CC BY-NC-SA 4.0 · xeno-canto
Identification
12–13 cm. In non-breeding plumage the upperparts are bright yellowish green and unstreaked, the face and sides of the neck grey with a prominent white eye-ring. The underparts are greyish white; adults often show a trace of chestnut on the flanks. Two yellowish to white wing bars. In March and April the male has a yellow crown, a black eye-stripe and malar stripe, white cheeks, a black-streaked back and a broad chestnut stripe along the flanks; the female then has the same pattern, but duller.
Confusion species
Bay-breasted Warbler Setophaga castanea in non-breeding plumage has a darker, faintly streaked green back, buff underparts and no white eye-ring. Tennessee Warbler Leiothlypis peregrina lacks distinct wing bars, has a pale supercilium instead of an eye-ring and a thinner bill. Female Cerulean Warbler Setophaga cerulea is greenish blue with a pale supercilium.
Habitat
In winter in forest edges, secondary forest, humid lowland forest and shade coffee, in the lowlands and on the lower slopes up to about 1500 m. It searches for insects under leaves in the middle level of the forest, often in mixed flocks, and in winter also eats small fruits. It does not breed in the guide area; the nest is placed low in shrubs in the north.
Where the bird is most at home, classified by the vegetation units of the Andes and the west coast.
Range and movements
Colombia: scarce winter visitor in the north-west and north, mainly in the Urabá region, the northern Chocó, the Caribbean lowlands and the lower slopes of the northern Andes. Ecuador: rare, with a few records. Peru and Bolivia: at most isolated records. Outside the guide area the species breeds in south-eastern Canada and the north-eastern United States and winters mainly from southern Mexico to Panama.
How and when to look
Look between November and March in mixed flocks along forest edges in north-western Colombia. A warbler with a bright green back, grey cheeks and a white eye-ring that holds its tail cocked is almost certainly this species.
Conservation status
Least Concern. The population is large; the species benefits from young woods and clearings on the breeding grounds, while lowland forest is being lost in the winter range.
Scientific name
Setophaga pensylvanica | (Linnaeus, 1766)
Linnaeus described the species in 1766 as Motacilla pensylvanica; because it was later moved to another genus, the author and year stand in brackets. The genus Setophaga was introduced in 1827 by Swainson. The genus name comes from Greek sēs (genitive sētos), 'moth', and -phagos, '-eating', so 'moth-eater'. The species name refers to Pennsylvania in the United States, not necessarily the type locality. The specimen the first description was based on came from near Philadelphia, Pennsylvania, United States.