Background:

Le Conte’s thrashers are a state and federal species of concern due to habitat destruction of an already disjunct range.  This thrasher ranges from southern Nevada and Utah through California and Arizona into northern Mexico in extremely arid and sparsely vegetated landscapes.  In Arizona, the Barry M. Goldwater Range contains the most of the Le Conte’s thrasher habitat within its extensive creosote flats.  This cryptic species can be difficult to detect as it typically forages elusively on the ground beneath shrubs and trees.  Thus, it is important to coordinate survey efforts so that the techniques employed are consistent across study areas.

Location:

The workshop was held in Gila Bend and on the Barry M. Goldwater Range in the San Cristobal Valley near Dateland and south of Interstate 8.

Approach:

We co-hosted a survey training workshop along with biologists from the 56th RMO from Luke Air Force Base.  This workshop brought biologists together from

 around the nation and Mexico to           Typical Le Conte’s thrasher habitat in the

 focus on Le Conte’s thrasher survey      San Cristobal Valley.

techniques and conservation issues.  Broadcast surveys were employed to maximize detectability.

Micro-habitat vegetation measurement collection procedures were also discussed which were collected within a 15-meter diameter circular plot centered at each confirmed nest location and each perch (with a GPS) from which Le Conte’s thrashers are first detected vocalizing during each survey.  Parameters collected at each plot included: type of perch used, perch height, and crown diameter.  Along six 15 meter transects radiating from plot center we used the point-intercept method to determine percent ground cover in five categories (bare ground, litter, dead woody debris, live vegetation or rock).  Vertical height indices for plant species were determined with a Robel pole at the point-intercepts along each transect.  The average                      Photo by Bruce Taubert               

height and mean crown diameter                                                       

calculated for all tree species within the plot.  Additionally, we took four photos at each cardinal direction shooting from the plot boundary to the center of the plot (i.e. the nest site or vocalizing perch).

Benefits: 

This workshop helped to standardize Le Conte’s thrasher surveys and stimulated conservation interest in this secretive species. 

For more information, please contact:
Scott Blackman , Arizona Game and Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086-5000. 
Phone: (520) 742-1911         Email: sblackman@azgfd.gov

Michael Ingraldi, Ph.D., Arizona Game and Fish Department
5000 W. Carefree Highway, Phoenix, AZ 85086-5000.
Phone: (928) 532-5625         E-mail: mingraldi@frontiernet.net