Survival of resident and translocated greater sage‐grouse in Strawberry Valley, Utah: A 13‐year study

Abstract

AbstractSurvival of greater sage‐grouse (Centrocercus urophasianus) has been well described in large populations across the species range. Very little published information exists, however, on survival rates of translocated sage‐grouse or grouse from a long‐term (>10 yr) study. Our objectives were to estimate seasonal and annual survival rates; assess differences in survival between resident and translocated, adult and yearling, and male and female sage‐grouse; identify environmental and behavioral factors associated with survival; and assess the influence of mammalian predator control on survival rates of radio‐marked sage‐grouse in Strawberry Valley, Utah from 1998 to 2010. We used a 2‐stage model selection approach using Akaike's Information Criterion corrected for sample size (AICc) with known‐fate models in Program MARK to evaluate the influences of seasonal, annual, demographic, and behavioral effects on survival rates of sage‐grouse. We captured and fitted 535 individual sage‐grouse (male and female, resident and translocated) with radio transmitters over a 13‐year period and monitored them weekly. The top model of survival, which accounted for 22% of the AICc weight, included 3 seasons that varied by year where rates were influenced by residency, sex, and whether a female initiated a nest. A group‐level covariate for the number of canids killed each year received some support as this variable improved model fit compared to identical models without it, although confidence intervals around β estimates overlapped zero slightly. All other demographic or environmental variables showed little or no support. Annual estimates of survival for females ranged between 28% and 84% depending on year and translocation source. Survival was consistently highest during the fall–winter months with a mean monthly survival rate of 0.97 (95% CI = 0.96–0.98). The lack of a control site and other potential confounding factors limit the extent of our inference with respect to predator control. Nonetheless, we suggest managers consider enhancing nesting habitat, translocating sage‐grouse, and possibly controlling predators to improve survival rates of sage‐grouse. © The Wildlife Society, 2013