John P. Severson; U.S. Geological Survey; 800 Business Park Dr. Suite D, Dixon, CA, 95620; (618) 559-2955; jpseverson@usgs.gov; Peter S. Coates, Brian G. Prochazka, Mark A. Ricca, Michael L. Casazza, David J. Delehanty
Wildlife researchers assume that tracking devices do not alter behavior or demographics, yet violations can bias ecological inference and misinform conservation actions. GPS units have improved our understanding of space use, but information on effects to demographics and behaviors is lacking. We evaluated survival and habitat selection using VHF and GPS units on >1,200 Greater Sage-Grouse (Centrocercus urophasianus), across multiple populations within the Great Basin. Survival was generally lower for GPS compared to VHF-marked grouse, but relative differences varied by sex, age, and season. We attributed decreased survival to features of GPS units that might increase susceptibility to predation such as greater unit weight, unit placement, and a reflective solar panel. Although habitat selection was generally similar, we observed some significant differences in selection of vegetation and terrain characteristics that may be related to predation risk or altered breeding success. Our results indicate that demographic parameters derived from GPS should be interpreted with caution, and design modifications aimed at reducing survival impacts would be beneficial. We provide body-mass based guidelines where survival impacts are reduced, but stress that more research on behavior is needed to assess tradeoffs associated with these units. Findings are preliminary and provided for timely best science.
Poster Session