
Photo: Lip Kee · CC BY-SA 2.0 (May be cropped or resized)
Muscicapa sibirica
Rare visitor: recorded only occasionally in this country
Dark-sided Flycatcher (Muscicapa sibirica) is a small sombre flycatcher with dark grey-brown upperparts, a smudged grey breast, pale belly and fine pale eye-ring. 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 breeds widely in the East Palearctic, waits upright on forest perches before making short flights after insects and migrates south to warmer Asian forests for winter. 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).