Technical Report
An Assessment of Potential Southwestern Willow Flycatcher Habitat: Los Lunas and San Marcial, New Mexico
Date: 2009/02/01
Author(s): Moore D.
Publication: Bureau of Reclamation Report, 12 p.
Abstract:
The Bureau of Reclamation (Reclamation) has been conducting studies of the endangered Southwestern Willow Flycatcher (Empidonax traillii extimus - SWFL) within several reaches of the Middle Rio Grande since 1995. Currently, breeding SWFLs are concentrated in suitable habitat within the conservation pool of Elephant Butte Reservoir and in a few isolated areas upstream including the Pueblo of Isleta, La Joya State Wildlife Area (SWA), Sevilleta National Wildlife Refuge (NWR), and the reach between Bosque del Apache NWR and San Marcial. During the past eight years, the SWFL population in the pool of Elephant Butte Reservoir has increased dramatically by dispersing into new, primarily native riparian habitat.
To facilitate recovery of this endangered subspecies in the Middle Rio Grande, it is necessary to understand habitat relationships and features selected by breeding SWFLs. The SWFL Recovery Plan (USFWS 2002) states that SWFL breeding habitat, although variable in terms of plant species composition, patch size and shape, and canopy structure, usually consists of a mosaic of dense vegetation, particularly in the first 3 to 4 meters above ground, and small openings, open water or shorter vegetation. Usually, surface water or saturated soil is present in proximity to breeding sites. However, dense is a very subjective term and few studies have quantified the habitat at SWFL breeding sites. These data are important for restoration efforts targeted for SWFL breeding habitat.