Although bat diversity across much of California has been relatively well studied, the Sacramento Valley remains a poorly documented region due to its extensive agricultural transformation and historical oversight during early 20th-century vertebrate surveys. To address this knowledge gap, we synthesized museum specimen records of bats collected in the Sacramento Valley from 1885 to 2025. Specimen data were compiled from 26 natural history collections through queried online databases (VertNet, ARCTOS, and UC Davis DIGICORE), filtered by location and georeferenced to determine seasonal and spatial patterns of bat occurrence. We summarized 690 specimens representing 14 bat species from 11 counties in the region. These data revealed distinct seasonal patterns of occurrence and sex-specific distributions for several species, including Eptesicus fuscus, Lasionycteris noctivagans, Lasiurus cinereus, and Lasiurus frantzii. Our findings demonstrate that historic specimen records can provide important insights into demography and seasonal movements of bats in regions where long-term acoustic or capture-based studies remain limited. This synthesis not only establishes an important historical baseline for bat distribution in the Sacramento Valley but also highlights the continued relevance of museum collections in contemporary ecological and conservation research.

Syd Benson is an early career biologist with a B.S. in Wildlife, Fish, and Conservation Biology from UC Davis (2024). As an undergraduate they worked at the UCD Museum of Wildlife and Fish Biology, where along with curation and fieldwork, they conducted a specimen-based bat research project. They currently work as a Scientific Aid with California Department of Fish and Wildlife’s Wildlife Diversity Program, supporting the state’s bat management and White-nose Syndrome response. Their work includes bat database revision, acoustic monitoring, roost surveys, and White-nose Syndrome surveillance. They also work with the Upland Game Program, supporting research through fieldwork and data processing on Gambel's Quail and Ring-necked Pheasants. They are passionate about applied research that informs bat and wildlife conservation and management.