Southwestern Willow Flycatcher

Natural System Modifications

As appropriate to local site conditions (e.g., topography, prevailing winds, disturbance history, infrastructure) (Urza et al. 2023) and not in persistent piñon (Pinus spp.)-juniper (Juniperus spp.) woodlands (Romme et al. 2009, Darr et al. 2022), thin stands of trees in forests and woodlands to natural or historic densities that reduce the probability of insect and disease outbreaks and stand-replacing wildfires and promote the growth of native understory cover (Redmond et al. 2023). Avoid unnecessary removal of large old-growth trees and snags, which serve as important wildlife habitat (Kalies and Rosenstock 2013); leave some juvenile trees or plant seedlings to promote establishment of new trees (Redmond et al. 2023); use best practices to maintain soil health (e.g., Tomao et al. 2020) including retaining sufficient seed trees and sources of mycorrhizal inoculum (Simard et al. 2021) and limiting pile burning and mastication where possible (Ross et al. 2012); implement landscape- and regional-scale heterogeneity in treatment design (Bradley 2009); and evaluate treatment effectiveness (e.g., McKinney et al. 2022, Davis et al. 2024, Hood et al. 2024), including monitoring local SGCN populations. Potential collaborators: BLM, NPS, USFS, SFD, SLO, non-profit organizations.

Invasive and Other Problematic Species, Genes, and Diseases

As needed, gather additional information regarding the distribution of tamarisk (Tamarix spp.) and other exotic plants in riparian habitats (e.g., NHNM 2023). Determine the impact of exotic plants, and their removal and reduction, on SGCN and their habitats. Create and implement site-specific plans, with measurable goals and objectives, to restore the historic structure and composition of riparian habitats while minimizing negative impacts on SGCN and soil health (Wagner 2023). Prioritize removal of monoculture stands of non-native plants (e.g., Johnson et al. 2018) and ensure that sufficient native riparian vegetation is locally available to SGCN and that local hydrological conditions support native vegetation regrowth. Since pollinating insects may use exotic riparian plants (e.g., Pendleton et al. 2011), minimize impacts of removing these plants on pollinating insect SGCN, including by avoiding herbicide application when plants are in bloom and treating the focal area in stages. Include post-implementation monitoring and maintenance for all riparian restoration projects. Document and report restoration approaches used, including successes and failures (Shafroth et al. 2008, Sogge et al. 2013). Potential collaborators: BLM, BOR, NPS, NRCS, USACE, USFS, USFWS, NMDA, SFD, SLO, SWCDs, universities, non-profit organizations, private landowners.

Natural System Modifications

Assess the impacts of stream-flow magnitude, frequency, timing, duration, and rate of change on riparian ecosystems and the effects of hydrologic alterations on these ecosystems. Determine flows needed to sustain SGCN and their habitats and the effects of flow modification by upstream dams and of upland disturbances in local watersheds (Goeking and Tarboton 2022). Work with agencies that manage dams and reservoirs to ensure released environmental flows match amounts and timing of flow needed for persistence of native riparian communities and associated SGCN, including allowing for overbank flows to coincide with seed dispersal from native vegetation (e.g., Greco 2013) and when saturated soil can best benefit SGCN prey. Potential collaborators: BOR, USACE, USFWS, USGS, NMED, NMOSE, universities, private industry.

Biological Resource Use Climate Change and Severe Weather Human Intrusions and Disturbance Invasive and Other Problematic Species, Genes, and Diseases Natural System Modifications Pollution Residential and Commercial Development

Assess the synergistic effects between climate change and other threats to SGCN and their habitats (e.g., Friggens et al. 2019, Parks et al. 2019). Incorporate appropriate climate adaptation strategies and frameworks into projects designed to address these synergistic effects. This may include enhancing connectivity (CEQ 2023), facilitating a species’ innate adaptive capacity (Thurman et al. 2022), enhancing genetic diversity (Powell 2023), considering local adaptation (Meek et al. 2023), or considering whether it is most appropriate to resist, accept, or direct ecosystem transformation (Lynch et al. 2021, Stevens et al. 2021). Projects should acknowledge ecosystem dynamism and incorporate indigenous knowledge (e.g., Roos et al. 2022, Eisenberg et al. 2024), nature-based solutions (Warnell et al. 2023), and experimentation (Guiterman et al. 2022) when appropriate. Potential collaborators: BLM, NPS, USFS, USFWS, USGS, universities, Tribal natural-resource managers.