Factors influencing the ecology of greater sagegrouse inhabiting the Bear Lake Plateau and valley, Idaho and Utah.

摘要

Greater sage-grouse (Centrocercus urophasianus; sage-grouse) occupy an estimated 56% of the potential pre-European settlement range. Prior to this study, little was known about the seasonal movements and habitat-use patterns of sage-grouse that inhabit the Idaho-Utah Bear Lake Plateau and Valley (BLPV) relative to landscapes and existing land uses. From 2010--2012, I captured, radio-marked, and monitored 153 sage-grouse (females and males) on the BLPV study area to determine factors affecting vital rates, seasonal movement, and habitat-use. Average annual survival rates of sage-grouse inhabiting the BLPV were 52.8% (+/-3.4%), with average female survival of 57.4% (+/-13.7%) and average male survival of 49.7% (+/-11.4%). Survival was best modeled by seasonal variation, with highest survival rates in the fall. Nest survival was low in comparison to range-wide estimates (15--86%), with average nest survival rates 23.2% (95% CL=17.6--28.8%). Brood success varied between 2011 and 2012, with higher brood survival in 2012. Some individuals were migratory, with close to half of radio-marked sage-grouse making seasonal movements >10 km. Average annual home range for BLPV radio-marked sage-grouse was 100.8 km2. Radio-marked sage-grouse used seasonal habitat in Utah, Idaho and Wyoming, suggesting that a tri-state management plan could benefit population conservation. Habitat selection was modeled using MaxEnt. MaxEnt software models species occurrence using presence-only data and geographic information systems environmental layers. Presence-only data are subject to sampling bias and cannot be used to determine abundance, though MaxEnt uses post-transformation of the raw output in an attempt to predict species prevalence across the landscape. Ten landscape-extent environmental and anthropological habitat variables were included in models to predict core use and connection areas. Models produced using these variables and BLPV sage-grouse locations ranked good to excellent fits (AUC >0. 81). The variables with the highest weight for predicting sage-grouse prevalence were distance to major road, distance to habitat edge, distance to tall vertical structure, and vegetation cover type. The habitat selection model was projected to an expanded area to identify potential habitat surrounding the BLPV. Coupling state-defined habitat with MaxEnt habitat models could provide baseline data to create and implement a tri-state management plan.