We investigated roost use by western long-eared bats (Myotis evotis), including roost fidelity, movement between roosts and the size of roosting home-ranges. We expected reproductive females, especially lactating females, to exhibit higher roost fidelity and to move shorter distances between roosts than males or nonreproductive females. Individuals generally switched roosts every 1 or 2 d. Despite their low roost fidelity, individuals occupied small roosting home-ranges (<2 ha), demonstrating fidelity to a roosting area. Roost fidelity, distances moved between roosts and roosting home-range sizes were not associated with reproductive class or reproductive period, possibly indicating that any energetic cost of roost switching is trivial in the energy budget of M. evotis, or that the advantages of roost switching outweigh any energetic cost.