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

Distribution, Abundance, and Breeding Activities of Southwestern Willow Flycatchers (Empidonax traillii extimus) at Select Locations on the San Luis Rey River, San Diego County, California—2024 Data Summary

Distribution and Abundance of Southwestern Willow Flycatchers (Empidonax traillii extimus) on the Upper San Luis Rey River, San Diego County, California—2023 Data Summary

Applying Satellite-based Habitat Models to Inform Riparian Habitat Restoration and Management Actions for Two Listed Riparian Species, the Southwestern Willow Flycatcher and the Yellow-billed Cuckoo 

  James Hatten1, Jennifer Holmes2, and Matthew Johnson3* 

An Integrated Pest Management Plan for the Bill Williams River National Wildlife Refuge. This plan outlines the biological degradation of native riparian forest habitat along the Lower Colorado River and the invasive species management actions needed to protect and restore riparian forests and marshlands of the Bill Williams River. 

DeRango, B., 2023. Integrated Pest Management Plan Bill Williams River National Wildlife Refuge.

A look into the use of invasive Tamarix (saltcedar, tamarisk) as habitat for birds in the southwestern United States and its implications for Tamarix control. While Tamarix habitat supports fewer birds than native habitat, data from Arizona Breeding Bird Atlas and Birds of North America demonstrate that 49 bird species use Tamarix as breeding habitat. The use and quality of Tamarix as bird habitat varies depending on geographic location and species and few studies have quantified the effects of Tamarix habitat on bird survivorship and productivity.

 A study that planted 474 trees and measured their growth characteristics for more than a year. Logistic regression was used to evaluate whether tree height, elevation above the river channel, distance to existing cottonwood or coyote willow, soil conductivity, soil texture, planting depth, planting method (mechanical auger vs. hand-digging), and provision of natural and commercial supplements affected survival probability. The authors found that survival probability was greater in auger-dug than hand-dug holes and increased with elevation above the river channel bottom.

An in-depth System for Assessing Vulnerability of Species modeling effort that looks at two dozen threatened and endangered species and how they may be affected by a changing climate. The authors provide a numerical scale of risk based on possible changes in habitat, physiology, phenology, and interactions across a scale of uncertainties. Results and discussion of the most critical factor for each species are presented.

A look at the potential for  southwestern willow flycatcher (Empidonax traillii extimus) adaptations to rising temperatures from an ecological genomics perspective. Compared to other willow flycatcher populations results indicate small, fragmented populations of the southwestern willow flycatcher will have to adapt most to keep pace with climate change.

Habitat factsheets and scorecards describe the habitat needs and behaviors of species of interest in the Colorado State Wildlife Action Plan. This particular document is for Southwestern Willow Flycatcher. These habitat details and score cards can be used to analyze current habitat conditions and potential for improvement.