Southwestern willow flycatcher (Empidonax traillii extimus) surveys in San Diego County, California, 2024

Data presented are results of surveys and monitoring in 2024 for Southwestern Willow Flycatcher (Empidonax traillii extimus) in San Diego County, California. Surveys were conducted at two locations along the middle San Luis Rey River (Bonsall and Rincon), and four locations along the upper San Luis Rey River (Cleveland National Forest, Rey River Ranch, Vista Irrigation District, and VID Lake Henshaw), and nest monitoring was conducted at Lake Henshaw. Surveys were conducted along multiple sections of the river where permission to access properties could be obtained. Locations were surveyed using a standardized protocol three to four times between 15 May and 31 July. The number, age (adult or juvenile), sex, banding status (color banded or not, and if so, color combination), and breeding status (paired, undetermined, or transient) of all willow flycatchers was recorded. The goal of nest monitoring was to collect baseline data on annual productivity, nest success, and parasitism rate. Monitored territories were visited weekly from May to August.

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  "010:12"
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  "geospatial"
]