Amur Ratsnake

The Amur ratsnake is a large, muscular nonvenomous snake. Adults are usually glossy black or very dark brown with narrow cream or yellow crossbars that fork or fade along the sides; the head carries pale markings around the jaws. Young animals are browner and more strongly blotched. Its bold black-and-yellow adult pattern, substantial body and long tail make it one of the region's most distinctive colubrids. (Wikipedia, Amur ratsnake account)

Amur ratsnakes use forest edges, river valleys, wetlands, rocky slopes and farmland in northeastern Asia. They are active by day, climb trees and buildings readily, swim well, and prey mainly on rodents, birds and eggs. Larger prey is constricted. Females lay clutches in warm concealed places and the species hibernates communally in cold climates. The opened general account did not confirm a specific Mongolian population or viewing site, so national distribution and timing are not elaborated here. (Wikipedia, Amur ratsnake account)