We were never able to get close to these attractive, but shy ducks. Although currently listed by IUCN as "least concern," a majority of the Asian population occurs in Japan where a 1990 winter census counted just 13,361 birds. This species was formerly much more common but seriously declined in the first half of the 20th century primarily because of overhunting and export for the aviculture trade. Digiscoped with Panasonic Lumix LX5 | Nikon Fieldscope III | 30X hand-held, no adapter.
Reference:
BirdLife International. 2018. Aix galericulata. The IUCN Red List of Threatened Species 2018: e.T22680107A131911544. http://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T22680107A131911544.en. Downloaded on 29 March 2019.
Carboneras, C. & Kirwan, G.M. (2019). Mandarin Duck (Aix galericulata). 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 https://www.hbw.com/node/52855 on 29 March 2019).