Why are Thomas’s pygmy mouse and its relatives rarely seen above ground?

Thomas’s pygmy mouse (Mus sorella) and its relatives are specialized burrowers that are rarely seen above ground because they spend the vast majority of their time within their underground tunnel systems. These mice are so elusive that they are typically only encountered when they are physically dug out of their burrows.1

Their anatomy is specifically adapted for this subterranean lifestyle, featuring protruding upper incisors and longer claws than most other species in the genus Mus, which facilitate efficient digging. While other mice may forage on the surface or construct nests in surface-level debris, these specialized burrowers remain hidden beneath the soil.1