The Forest Wagtail is a distinct migratory species, notable as the only member of its family to build nests on trees. Primarily breeds in East Asia, including southeastern Siberia, Ussuriland, Sakhalin, North/South Korea, and eastern/northeastern China (Gansu, Anhui, Hunan).
They build cup-shaped nests, often 2–7 meters high in trees, frequently in oaks. They are full migrants, leaving breeding areas in late August and arriving in non-breeding grounds between late September and October.

The Forest Wagtail is common migrant species in Malaysia, known for its unique habit of swaying its tail side-to-side (not up-and-down like other wagtails) as it forages in woodlands and forest paths, mangroves at low tide, for insects and spiders, featuring olive-green upperparts, distinctive wing-bars, and a black bib. Will either walk away or flush onto trees if suddenly disturbed.

Very common during the migratory season at the Teluk Air Tawar – Kuala Muda IBA, also found inland at scrubs, orchards, and planations, but not in the open, like paddyfields or grasslands.

https://datazone.birdlife.org/species/factsheet/forest-wagtail-dendronanthus-indicus