This species goes under the name Buff-bellied Pipit in European literature but in winter they lack the buff-colored underparts which this species gets in the breeding season. At that time the underparts may be largely unstreaked. This is the heavily marked, pink-legged japonicus subspecies which ranges through east Asia. Canon PowerShot SX60 HS.
References:
Alström, P. & Mild, K. (2003) Pipits & Wagtails of Europe, Asia and North America. Identification and Systematics. Christopher Helm, London.
Hendricks, Paul and N. A. Verbeek.(2012).American Pipit (Anthus rubescens), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/amepip DOI: 10.2173/bna.95
Tyler, S. & Kirwan, G.M. (2017). Buff-bellied Pipit (Anthus rubescens). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/57806 on 29 June 2017).