The southern birch mouse (Sicista subtilis ) is a species of birch mouse in the family Sminthidae. It is native to southern Russia, Kazakhstan, and potentially northern Mongolia and China.
The most prominent characteristic of the southern birch mouse is the dark stripe down the center of the back, which is bordered by two narrow bright stripes on both sides. From head to rump it measures from 56 to 72 mm, with a tail from 110 to 130% of the main body length. The background fur color is gray-brown.
The southern birch mouse is pronouncedly a steppe dweller. It makes a burrow in the summer and hibernates. It eats green plants and insects.