How do mice in the genus Mus build and use burrows?

Mice in the genus Mus are primarily ground dwellers that exhibit varied approaches to shelter. While some species, such as the gray-bellied pygmy mouse, do not burrow and instead utilize existing pathways, many others—particularly those in savanna and grassland habitats—excavate burrows and chambers to house globular nests made of dry vegetation.1

The excavation process is simple but effective. For example, the Ryukyu mouse uses its incisor teeth to loosen soil. It then carries the debris in its mouth to pile it outside the entrance or stacks the loose soil inside before pushing it out with its hind feet. In environments like the diked rice fields of Thailand, these tunnels are strategically constructed to extend upward to a nest chamber located above the water level, often featuring openings on both sides of a dike.1

While some species are specialized burrowers that are rarely seen above ground, forest-dwelling mice may alternatively construct their nests in rock crevices or beneath rotting tree trunks and brush piles on the forest floor.1