Identifying Restoration Priorities for the Southwestern Willow Flycatcher Based upon Impacts of Tamarisk Leaf Beetle (Diorhabda spp.) in the Middle Rio Grande
Ondrea Hummel1*, Danielle Galloway2*, Joe Schroeder3*, Chris Sanderson4*, Alaina Pershall5*
1Tetra Tech, Albuquerque, NM, USA; Ondrea.Hummel@tetratech.com
2U.S. Army Corps of Engineers, Albuquerque, NM, USA; Danielle.A.Galloway@usace.army.mil
3Tetra Tech, Albuquerque, NM, USA; Joe.Schroeder@tetratech.com
4Tetra Tech, Albuquerque, NM, USA; Chris.Sanderson@tetratech.com
5Tetra Tech, Albuquerque, NM, USA; Alaina.Pershall@tetratech.com
In 2014, Tetra Tech completed a study entitled: Habitat Relationships along the Middle Rio Grande in New Mexico for the Endangered Southwestern Willow Flycatcher (Tetra Tech 2015), which identified priority areas for potential habitat restoration to benefit the federally endangered Southwestern Willow Flycatcher (Empidonax traillii extimus, flycatcher). The 2014 analysis evaluated habitat relationships for the flycatcher including riparian species composition and structure, patch size, location of existing breeding territories, surface hydrology and groundwater interactions, fire, salt cedar (Tamarix spp.), and tamarisk leaf beetle (Diorhabda spp., TLB) defoliation and movement. This analysis was completed for the Middle Rio Grande Endangered Species Collaborative Program (Program), under contract with the U.S. Army Corps of Engineers.
TLB surveys performed in 2018 have shown the convergence of three TLB species in the Middle Rio Grande (Johnson, 2018). The spread of TLB (Diorhabda carinulata) from the north and potential spread of D. sublineata and D. elongata from Texas will ultimately affect riparian forests in central and southern New Mexico (Johnson and Jamison, 2017).
Since the 2014 analysis, several key flycatcher habitat relationships have changed including the location of breeding territories, habitat affinities, population expansion and contraction areas in addition to habitat modifications through fire, planned or completed habitat restoration projects, and the convergence of these three species of TLB in the Middle Rio Grande. Consequently, the habitat restoration prioritization analysis is being updated to address these changes and provide guidance for restoration activities. Updates to the original analysis are designed to allow the Program to work on sites that are: a) being affected by TLB and therefore could potentially affect the flycatcher; and b) perform restoration at sites that have a lower percentage of salt cedar present and promote suitable habitat for the flycatcher.