Distribution and abundance of Southwestern Willow Flycatchers (Empidonax traillii extimus) on the upper San Luis Rey River, San Diego County, California—2020 data summary

Distribution and abundance of Southwestern Willow Flycatchers (Empidonax traillii extimus) on the Upper San Luis Rey River, San Diego County, California—2021 data summary

“…In total, three territories were established, consisting of two pairs and one male of undetermined breeding status. The number of territorial flycatchers observed downstream from Lake Henshaw decreased by 55 percent compared to 2020 (11; Howell and Kus, 2021;Howell and Kus, 2022).…”

“…However, unlike the vireo, which has increased tenfold since the mid-1980s in response to management practices alleviating threats (U.S. Fish and Wildlife Service, 2006), the number of flycatchers has remained low. Currently, the majority of flycatchers in California are concentrated at one site: the upper San Luis Rey River at Lake Henshaw in San Diego County (Howell and Kus, 2021). Outside of this site, flycatchers occur as small, isolated populations of one to six pairs.…”

“…Kus, U.S. Geological Survey, unpub. data, 2015-19;Howell and Kus, 2021). The data contained in this report can be found in the associated data release (Howell and Kus, 2022) These data, when compared with data from other sites, will inform natural resource managers about the status of the flycatcher on the upper San Luis Rey River and guide modification of land-use and management practices as appropriate to ensure the species' continued existence.…”

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—2021 Annual report

“…However, unlike the vireo, which has increased tenfold since the mid-1980s in response to management efforts, Willow Flycatcher numbers have remained low. Currently, most flycatchers in California are concentrated at one site, the upper San Luis Rey River, near Lake Henshaw, in San Diego County (Howell and Kus, 2021). Outside of this site, flycatchers occur as small, isolated populations of one to six pairs.…”

Distribution and abundance of Least Bell’s Vireos (<i>Vireo bellii pusillus</i>) and Southwestern Willow Flycatchers (Empidonax traillii extimus) at the Mojave River Dam, San Bernardino County, California—2021 Data summary

“…However, unlike the vireo, which has increased tenfold since the mid-1980s in response to management practices alleviating threats (U.S. Fish and Wildlife Service, 2006), the number of flycatchers has remained low. Currently, most flycatchers in California are concentrated at one site, the upper San Luis Rey River near Lake Henshaw in San Diego County (Howell and Kus, 2021). Outside of this site, flycatchers occur as small, isolated populations of one to six pairs.…”