also sleep. The food of M. squamatus consists of aquatic arthropods, frogs and small to medium-sized fish. Stonefly (Plecoptera) and Phryganeidae giant caddisfly larvae may constitute the bulk of its diet when available. Beetles and crustaceans are eaten less regularly, though the latter may be more important in autumn. As aquatic insect larvae hatch in the course of the summer, fish become more prominent in the diet. Favorite fish species include the dojo loach (Misgurnus anguillicaudatus) and the lenok Brachymystax lenok. More rarely eaten are such species as the lamprey Eudontomyzon morii, the sculpin Mesocottus haitej, or the Arctic grayling (Thymallus arcticus). Thus, they are opportunistic feeders; regarding fish, they will probably eat any species that has the correct elongated shape and small size. Scaly-sided mergansers nest in trees, as typical for the merganser and goldeneye lineage of sea ducks. Preferred nesting trees are such species as daimyo oak (Quercus dentata, ), Chozenia, Linden and Ussuri poplar (Populus ussuriensis, 大青杨; a balsam poplar). Easy breed in artificial nest boxes on the rivers with destroyed forests on banks. They are sympatric with Mandarin ducks (Aix galericulata); perhaps competing for nesting holes (which neither can excavate themselves). In its winter quarters, the scaly-sided merganser might compete with other Merginae with which it shares its habitat then, e.g. common mergansers (M. merganser) and common goldeneyes (Bucephala clangula). Status This species is considered endangered by the IUCN. Its numbers declined in the 1960s and 1970s due to loss of primary forests in its limited range, particularly along the major rivers in Russia. Current threats include illegal hunting, entanglement in (ghost) fishing nets and river pollution, as well as ongoing destruction of forest. According to its current IUCN classification EN C2a(ii), fewer than 5000 adult and first and second year old birds remain, and most of these are found in Primorye and South Khabarovsk regions of Russia (85%) World population survey was completed in 2014 both in Russia and China, the number for North Korea was estimated without survey there. Surveys on dispersal wintering grounds are useless and the way to estimate world population is to survey pristine rivers within breeding range. Rivers of Central China, primarily tributaries of Yangtze River, and all rivers of South Korea constitutes the wintering area well known nowadays. Habitat loss in China led to breeding range reduction and fragmentation there. In Russia population seems to stabilize in 1900th and