Number of pages: 26

Authors: Howell, Scarlett L.; Kus, Barbara;

Year: 2024

Purpose: The purpose of this study, which began in 2015, was to document the status of Southwestern Willow Flycatchers in San Diego County, California. The goals of the 2024 effort were to (1) assess the status of the flycatcher population at select locations in San Diego County, including two along the middle San Luis Rey River near Bonsall and four along the upper San Luis Rey River near Santa Ysabel; (2) assess the breeding activities of the flycatcher at Lake Henshaw, including nest success and productivity; and (3) evaluate the level of cowbird parasitism at Lake Henshaw. This report is the annual update to surveys that have been completed since 2015 (Howell and Kus, 2021, 2022a, b, 2023, 2024a). The data contained in this report can be found in the associated data release (Howell and Kus, 2022b). These data, when compared with data from other sites and years, will inform natural resource managers about the status of the flycatcher on the San Luis Rey River and may help guide modification of land-use and management practices as appropriate to ensure the species’ continued existence.

Keywords: bird surveys; endangered species;

Species: Southwestern willow flycatcher

Vegetation communities: riparian forest & scrub

Projects:

• Southwestern Willow Flycatcher Brown-headed Cowbird Demographic Monitoring