Japanese Bush Warbler

Japanese Bush Warbler (Horornis diphone) is a plain olive-brown warbler with a long pale eyebrow, rounded wings and a tail often held slightly raised. Body shape, bill structure, plumage pattern and voice provide the strongest field characters. Age, sex and season may alter its appearance, so identification should combine several features and careful direct field comparisons with similar species in the same habitat (Wikipedia, general species account).

It stays low in dense scrub, bamboo and forest undergrowth, feeding on insects and remaining much easier to detect by the male's distinctive spring song than by sight across much of East Asia. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds gathering where food is concentrated. The Korean vertebrate catalogue used for this guide records the species in South Korea (Wikipedia, general species account; Wildlife of Korea occurrence records).