Loss of roosting resources negatively affects bat populations. For sensitive species, such as the Townsend’s big-eared bat (Corynorhinus townsendii), determining roost locations and requirements is a critical component in conserving their habitat. Such cavity roosting bats on the North Coast of California are known to use hollows in large redwood trees. We examined the relative amount of use of basal tree hollows by different bat species at eight coastal redwood forest sites. Observations of bats were expected to be rare, and this was confirmed with just 13 observations in 1547 hollow visits. For this reason, bat guano was collected to determine roosting activity and species use (179 hollows visited monthly from 2017 to 2018). To identify species, DNA analysis was performed at the Northern Arizona University “Species from Feces” lab. Nine bat species and one species group were identified using hollows. Of 253 species identifications from 83 hollows, the most prevalent were Myotis californicus (28.5% of all identifications), the M. evotis-M. thysanodes group (17.4%), C. townsendii (17.0%), and M. volans (15.0%). These findings can inform land managers when planning conservation and management of redwood forests.