Distribution and Abundance of Least Bell’s Vireos (Vireo bellii pusillus) and Southwestern Willow Flycatchers (Empidonax traillii extimus) at the Mojave River Dam, San Bernardino County, California—2024 Data Summary
In 2024, researchers surveyed for Least Bell’s Vireos and Southwestern Willow Flycatchers at the Mojave River Dam study area near Hesperia, California. During four vireo surveys, three territorial males were detected, all paired, with no juveniles observed, occupying riparian scrub and willow-cottonwood habitats dominated by red or arroyo willow. Three flycatcher surveys detected no territorial or transient individuals.
Howell, S.L., and Kus, B.E., 2025, Distribution and abundance of Least Bell’s Vireos (Vireo bellii pusillus) and Southwestern Willow Flycatchers (Empidonax traillii extimus) at the Mojave River Dam, San Bernardino County, California—2024 data summary: U.S. Geological Survey Open-File Report 2025–1025, 8 p., https://doi.org/ 10.3133/ ofr20251025.