Effects of Radio Collars on Survival and Lekking Behavior of Male Greater Sage-Grouse

Abstract

Monitoring of birds often requires the use of very-high-frequency radios or satellite telemetry to enhance detectability of individuals. An assumption implicit in such studies is that radio-marked individuals are representative of the population at whole, which requires that radios do not influence an individual's behavior or demographics. We present results from a capture-mark-recapture study of male Greater Sage-Grouse (Centrocercus urophasianus), some radio collared, others only banded, in an experimental framework to assess whether radio collars influenced the birds' behavior or survival. We generated encounter histories of 906 male Greater Sage-Grouse and used a robust-design framework in program MARK to estimate probabilities of annual survival, detection, and temporary emigration from the lek for the radio-collared and banded segments of the sample population. Results of models suggested that seasonal detection rates at leks the year after capture were 3-5 times higher for males only banded than for males equipped with radio collars. These results also suggested a possible negative influence of radio collars on males' annual survival and annual lek attendance. We suggest researchers should exercise caution when designing studies or analyzing data that rely on radio-collared male Greater Sage-Grouse.