Eurasian Particolored Bat

The parti-coloured bat is a medium-sized vesper bat with dark brown dorsal fur strongly frosted by pale silver tips. The belly is whitish or grey, while the face, ears, and membranes are dark. Adults measure roughly 48–66mm and weigh 10–24g. Narrow wings and a contrasting black-and-silver back distinguish it from uniformly brown serotines, although close views or acoustic confirmation are advisable. (Wikipedia, general species account)

Its Eurasian range crosses eastern and northern Europe into temperate Asia. It forages over open forest, steppe, farmland, wetlands, and settlements, catching flying insects. Summer roosts occur in buildings, trees, and rock crevices; winter sites include tall buildings and cliffs. Females commonly bear twins, unusual among many temperate bats. Reliable Mongolia-specific viewing localities were not identified in the opened source. (Wikipedia, general species account)