Field voles, active by day and night, are aggressive and each one has its own small territory which it fiercely defends from other voles. They fight noisily, uttering loud squeaks and angry chattering noises. Each vole makes runways among the grass stems, usually centered on a tussock where it nests.
A favourite habitat is a young foresty plantation where there is lush, undisturbed grass. But after a few years, the trees have grown so much that they cast a dense shade and the grass dies, forcing the voles to go somewhere else. Some manage to live on the grassy fringes, from where they can quickly recolonise grassy areas that begin to grow once more trees are felled.