The spinifex hopping mouse (Notomys alexis), also known as the tarkawara or tarrkawarra, occurs throughout the central and western Australian arid zones, occupying both spinifex-covered sand flats and stabilised sand dunes, and loamy mulga and melaleuca flats. The population fluctuates greatly: in normal years it is sparsely distributed and probably confined to sandy country; after rain the population explodes and spreads to other types of habitat for a time. They are mostly seen at night, bounding across open ground on their large hind feet, with tails extended and the body almost horizontal.