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Distribution and abundance of Least Bell’s Vireos (Vireo bellii pusillus) and Southwestern Willow Flycatchers (Empidonax traillii extimus) at the San Antonio Dam, Los Angeles and San Bernardino Counties, California—2021 Data summary

January 18, 2022

Executive Summary

We surveyed for Least Bell’s Vireos (Vireo bellii pusillus; vireo) and Southwestern Willow Flycatchers (Empidonax traillii extimus; flycatcher) at the San Antonio Dam near Upland, California, in 2021. Four vireo surveys were conducted between April 16 and July 15, 2021, and three flycatcher surveys were conducted between May 27 and July 15, 2021.

We detected one transient vireo and one transient flycatcher. No territorial vireos or flycatchers were observed. The vireo was found in riparian scrub habitat dominated by native mule fat (Baccharis salicifolia), whereas the flycatcher was using habitat dominated by non-native tamarisk (Tamarix ramosissima).

Publication Year 2022
Title Distribution and abundance of Least Bell’s Vireos (Vireo bellii pusillus) and Southwestern Willow Flycatchers (Empidonax traillii extimus) at the San Antonio Dam, Los Angeles and San Bernardino Counties, California—2021 Data summary
DOI 10.3133/dr1148
Authors Scarlett L. Howell, Barbara E. Kus
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Data Report
Series Number 1148
Index ID dr1148
Record Source USGS Publications Warehouse
USGS Organization Western Ecological Research Center