Spatial ecology of the lower Colorado River valley population of Greater Sandhill Cranes

Due to lack of baseline ecological information on the Lower Colorado River Valley Population (LCRVP) of greater sandhill cranes (Grus canadensis tabida), management efforts have been delayed and further research on the winter ecology, migratory paths, and breeding distribution of this population is warranted. We fitted 18 greater sandhill cranes on three study sites in southwest Arizona, southeast California, and west-central Idaho January–July 2014 with platform transmitter terminals (PTTs). PTTs recorded four global positioning system locations per day per bird. For our overwinter space use assessment, we calculated average winter home range size using the Brownian bridge movement model (BBMM). Average winter home range size was 18,710 ha (SE= 3809). In the overwinter habitat selection study, we used selection ratio-based resource selection functions and found habitat types including water, barren, and other were selected for at the sampled population level. In the migratory connectivity and new summer area study, we used the BBMM to assess migration corridors and migratory pathways, then outlined all PTT locations outside of the known LCRVP breeding distribution during the 2014 and 2015 summers. Fall and spring migration corridors covered similar areas. We identified 19 stops throughout the three migration events and we identified 3 new summer units. Targeting habitat management of roost site availability on the LCRVP wintering grounds, at migratory stops, and conducting comprehensive banding efforts on western sandhill crane populations could address winter and migratory concerns for this population and provide further evidence of intermixing between western populations.