Movements and Survival of Juvenile Greater Sage-Grouse in Southeastern Idaho

Abstract

Low recruitment has been suggested as a primary factor contributing to declines in greater sage‐grouse (Centrocercus urophasianus) populations. We evaluated movements and survival of 58 radiomarked juvenile greater sage‐grouse from 1 September (≥10 weeks of age) to 29 March (≥40 weeks of age) during 1997–1998 and 1998–1999 in lowland and mountain valley study areas in southeastern Idaho, USA. Juvenile sage‐grouse captured in the mountain valley area moved an average of 2.2 km (20%) farther (x̄ = 13.0 km, SE = 1.2 km) from autumn to winter ranges than juvenile grouse captured in the lowland area (x̄ = 10.8 km, SE = 1.2 km). Ten of 11 deaths occurred from September to December. Fifty percent of deaths in the lowland population were attributable to human‐related mortality including power‐line collisions and legal harvest, while 33% and 17% of deaths were attributable to mammalian predators and unknown cause, respectively. All deaths in the mountain valley population were attributed to avian or mammalian predators. Survival was relatively high for birds from both populations, but was higher across years in the lowland (Ŝ = 0.86, SE = 0.06, n = 43) than in the mountain valley population (Ŝ = 0.64, SE = 0.13, n = 14). In our study juvenile sage‐grouse that moved farther distances to seasonal ranges experienced lower survival than juveniles from a more sedentary population. Moreover, high juvenile survival in our study suggests that if low recruitment occurs in sage‐grouse populations it may be due to other factors, especially poor nesting success or low early chick survival.

Evaluating vital rate contributions to greater sage‐grouse population dynamics to inform conservation

“…Postfledging survival appears malleable and therefore is likely to respond to management actions. To achieve a net long-term gain, an understanding of the impact of beneficial and detrimental years of various environmental conditions on postfledging female survival and the interaction with conservation actions is needed, especially for juvenile survival where to date information has been scarce (Beck et al 2006, Caudill et al 2014.…”

Microhabitat Selection of Brood-Rearing Sites by Greater Sage-Grouse in Carbon County, Wyoming

“…We characterized the vegetation and arthropod community at GPS locations of the female rearing a brood to assess selection of brood-rearing sites. For each brooding female, we selected and measured resources at ≥1 location during the first 7 d post-hatch, ≥1 location during 8-14 d posthatch, and ≥1 location approximately every 14 d until the chicks were absent or reached 70 d of age, representing independence (e.g., Beck et al 2006, Thompson 2012. All locations selected for measurements were diurnal locations from the previous 4 days.…”

Population structure and genetic diversity of greater sage-grouse (Centrocercus urophasianus) in fragmented landscapes at the northern edge of their range

“…Evidence for both sexes dispersing is contrary to the common assumption that galliform females disperse and males are philopatric (Schroeder and Braun 1993), however similar average dispersal distances for both sexes has been observed in sage-grouse in Colorado (8.8 km for females versus 7.4 km in males; Dunn and Braun 1985). Traditional radio-transmitter studies have documented individual sage-grouse dispersal of only 5-20 km (e.g., Beck et al 2006), but have not captured maximum dispersal distances and evidence of male dispersal due to infrequency of long distance dispersal events, lack of monitoring juvenile birds prior to and after dispersal, and logistical difficulty of tracking individuals over long distances. These studies have also not accurately documented the dispersal ability of both sexes because most sage-grouse telemetry studies have been conducted on females.…”