Completion Form

2024

This study proposed to capture and sample the subspecies of willow flycatchers at known detection sites along the Green, Colorado, Dolores Rivers and other Moab, UT BLM district drainages to determine the willow flycatcher subspecies status through genetic testing as well as measuring plumage/morphometric and song.  The results of this research will have management implications in determining which subspecies occupies these river systems and will also contribute to the clarification of the breeding ranges of these willow flycatcher subspecies. In 2023, we captured and sampled blood and feathers from 16 individual willow flycatcher along the Colorado River, UT. We also obtained additional (n = 47) feather samples from the University of Utah working at the Rio Mesa Research Station along the Dolores River, UT. Therefore, we sent a total of (n = 63) genetic samples to colleagues at Colorado State University for genomic analyses. In 2023, our willow flycatcher genetic analysis validated 96 genome-wide markers from the reference library used by Ruegg et al. (2018). Samples were classified to the seven distinct breeding origins characterized by Ruegg et al. (2018) We then evaluated the accuracy of our assignment of individuals to the seven breeding origins  and found that the assignment individual willow flycatchers to breeding origin was high. All sampled individual willow flycatcher were classified with high probabilities to the interior west (INW), pacific northwest (PNW), and eastern (EST) (Ruegg et al. 2018). The breeding origins corresponded to the ranges of non-endangered subspecies of E. t. adastus, E. t. brewsteri, and E. t . traillii, respectively. We identified (n = 7) individuals that represented admixtures between those same breeding origins containing nonendangered subspecies willow flycatchers. The probability of any individual containing any ancestry from the breeding origin containing E. t. extimus (i.e., Southwestern Willow Flycatcher) was less than 0.007 and considered 0.  In 2023, we also recorded (n = 8) singing willow flycatchers and classified subspecies identity and assessed relationships between song, morphology, and plumage color among those individuals. From our analysis, 100% of individuals were classified as  the Interior West Willow Flycatcher (E. traillii adastus) the Pacific Northwestern Willow Flycatcher (E. traillii brewsteri). None were classified as the Southwestern Willow Flycatcher (E. traillii extimus) In 2023, we also completed Southwestern Willow Flycatcher standardized surveys (as recommended in the Southwestern Willow Flycatcher survey protocol (Sogge et al. 2010) at each survey site that we captured willow flycatchers for the genetic, song morphology, and plumage color analysis. In 2023, we did not complete a standardized survey during survey period one (1531 May) since the objective was to capture willow flycatchers to complete the objectives of this study. In 2023, we completed two surveys at sites we captured willow flycatchers had no detections during the second survey (11 - 24 June) or the third survey (25 June -- 17 July) which continues to support that willow flycatchers of any sub-species are not breeding in this region and continues to use this region as stop over migration habitat.

Please see the final methods outlined in the final report uploaded to the Images/Docs Section for more detailed information.

The project was executed through agreement with RiversEdge West (REW).  REW managed partner involvement from EcoPlateau Research, University of Arizona, and Colorado State University.  The project budget was increased in early 2023 and the project extended from a 1 year to a 3 year project to address additional questions. Below is an explanation of the additional costs and research scope supplied by REW and partners:

- The original budget proposed monitoring only Cataract Canyon primarily by boat, but we have broadened the scope of our surveys to capture a broader range of habitat along the Colorado, Dolores, and Green Rivers, which are largely accessible by foot and road. We have increased the lodging line item and mileage accordingly.

- We have requested additional hours to also check for any evidence of SWFL breeding in this habitat, as well as a trial to check for fall migrants using the habitat.

- Due to inflation, costs have increased in labor, fuel, and laboratory materials. We have accounted for these increased costs.

- We request additional funds to sex genotype individuals (n=50-100 individuals). This information is important because it will allow us to determine if female Willow Flycatchers sing and subsequently test for song differences between sexes. As survey efforts move towards Autonomous Recording Units, this work will inform applications that could be used to determine sex ratios of birds in the field and track demographic parameters critical to endangered species management. If we can validate sex identification via recording units with truthed genotype-based sexing this could improve SWFL management and save money for future field surveys.
  
- We offset some increases in costs by bringing the genetics analysis in-house with our new staff scientist position, collaborating universities (CSU and UA), and by working with a local sponsor to support the rafting supplies.

- If we find SWFL in this area, we could use genetic, and possibly autonomous recording units, to monitor SWFL habitat-use long-term.

The project concluded early following year 2 because the required Section 10 permits could not be acquired in the timeframe necessary to continue the project.  The final report is uploaded to this project page.

Gabriel Bissonette

08/30/2024 15:16:06