The Japanese bush warbler, known in Japanese as uguisu (鶯), is an Asian passerine bird more often heard than seen. Its distinctive breeding song can be heard throughout much of Japan from the start of spring.
Region
East Asia and Hawaiian Islands
Typical Environment
Primarily found across the main Japanese islands, including lowland to montane forests, bamboo groves, and shrubby hillsides. It favors dense undergrowth, forest edges, and regenerating clearings where cover is abundant. In winter it may move to lower elevations and milder coastal areas. Introduced populations in Hawaii occupy non-native shrublands, gulches, and forest edges with thick understory.
Altitude Range
0–2500 m
Climate Zone
Temperate
Ease of Keeping
Beginner friendly: 1/5
Known in Japanese as uguisu, the Japanese bush warbler is famed for its clear, ringing spring song that often reveals its presence before the bird is seen. It is a shy skulker of thickets, slipping through dense cover with ease. The species has been introduced to the Hawaiian Islands, where it occupies similar shrub habitats.
Eggs of the Japanese bush warbler.
Japanese bush warbler singing.
Temperament
secretive and skulking
Flight Pattern
short rapid wingbeats in low, darting flights
Social Behavior
Generally solitary or in pairs during the breeding season, when males defend territories vigorously through song. Nests are cup-shaped and placed low in dense shrubs or bamboo. Pairs are typically monogamous within a season, with both adults involved in rearing young.
Migratory Pattern
Partial migrant
Song Description
A loud, clear, and resonant series of whistles, famously associated with the start of spring in Japan; the song carries far from dense cover. Calls include sharp metallic chips and scolds when alarmed.
Plumage
Plain, soft-textured plumage with olive-brown upperparts and gray-buff underparts; often shows a pale eyebrow and slightly warmer buff flanks. Tail is fairly long and often flicked; wings are rounded.
Diet
Primarily small insects and other arthropods such as beetles, caterpillars, and spiders, gleaned from foliage and twigs. It occasionally takes small berries when insects are scarce. Forages methodically within cover, often near the ground or in low shrubs.
Preferred Environment
Dense thickets, bamboo stands, and shrubby forest edges where it can stay concealed while foraging. In Hawaii it uses similar dense understory in both native and non-native vegetation.
