Least Bell's Vireos and Southwestern Willow Flycatchers at the San Luis Rey Flood Risk Management Project Area in San Diego County, California: Breeding Activities and Habitat Use—2022 Annual Report
In 2022, surveys for Southwestern Willow Flycatchers detected only four transient individuals, with no residents. Vegetation sampling across 46 transects and 44 nest/territory plots indicated that vireos selected territories and nest sites with specific foliage heights, with Channel sites having denser mid-canopy cover but less low vegetation compared to available habitat, while foliage cover trends varied by site over time. Overall, the 2022 data provide insights into population dynamics, reproductive success, habitat selection, and the influence of vegetation management on vireo breeding and territory establishment.
Houston, A., Allen, L.D., Mendia, S.M., and Kus, B.E., 2023, Least Bell's Vireos and Southwestern Willow Flycatchers at the San Luis Rey Flood Risk Management Project Area in San Diego County, California—Breeding activities and habitat use—2022 annual report: U.S. Geological Survey Open-File Report 2023–1040, 74 p., https://doi.org/10.3133/ofr20231040.