Bangladesh, Cambodia, China (mainland) (B), India, Laos, Mongolia (B), Myanmar, Nepal, North Korea, Russia (Asian) (B), Russia (Central Asian) (B), South Korea, Thailand, Vietnam.
Vagrant to Bhutan, Egypt, Hong Kong (China), Japan, Malaysia, United Kingdom.
Rarity Status
Currently this species is not classified as a rarity in this country OR information has not been updated.
Population
Estimated population is unknown (2010).
Thick-billed Warbler (Arundinax aedon) [XC485178]
by Bram Piot from Kabansky District, Buryatia, Russian Federation (song)
Thick-billed Warbler (Arundinax aedon) [XC845334]
by id from Mekong channels, Sangthong district, Vientiane Prefecture, Laos (call)
Subspecies
Sometimes placed in a separate genus, Phragmaticola; when so treated, earlier name rufescens (which preoccupied in present genus) can be used for eastern subspecies stegmanni. Relationships uncertain. Further research is needed. Subspecies intergrade.
The following 3 subspecies are recognised:
aedon (Pallas, 1776) - Breeds south-central Siberia (from Tomsk east to Kansk, south to L Teletskoy in Altai and to eastern Sayan Mts) and adjacent north-western Mongolia. Non-breeding Nepal and eastern and southern India east to Myanmar and Thailand.
stegmanni Watson, 1985 - Breeds eastern Siberia and north-eastern Mongolia east to Sea of Japan, south to north-eastern China. Non-breeding southern China, Thailand and Indochina.
rufescens (Stegmann, 1929) - Eastern Siberia to Mongolia. Winters to south-eastern China, Thailand and Indochina.
BirdLife International Species Factsheet