Demography, reproductive ecology, and variation in survival of greater sage-grouse in northeastern California

Abstract

We examined demographic parameters and factors influencing nest survival of female greater sage‐grouse (Centrocercus urophasianus) in northeastern California. Additionally, we used known‐fate models in program MARK to examine bi‐weekly survival rates of females over an 8‐month period (Mar–Oct, 2007–2009). Nest survival rate, assuming a 38‐day exposure period, was 41% and was positively associated with grass height (trueβˆ = 0.03, SE = 0.02), but the 95% confidence interval overlapped 0 (95% CI = −0.007–0.767) and the effect of grass height on nest success was likely to be small. Grass height and visual obstruction was greater at nest sites than at random locations, suggesting females selected sites with structurally more closed habitat for nesting. Females that nested under vegetation other than sagebrush (Artemisia spp.) had increased nest survival probabilities, suggesting sage‐grouse selection of nest sites is based on vegetation structure more than plant species. Sagebrush canopy cover was considerably lower in our study area (approx. 10% on random plots) compared with sagebrush cover described across the geographic range of sage‐grouse (>15%) and sage‐grouse use of non‐sagebrush plants in our study suggests sagebrush nesting habitat is limited. The overall 8‐month survival (breeding season through autumn migration) for female sage‐grouse was 49% (SE = 0.06) with most deaths occurring in spring and autumn. Mortalities during spring coincided with nest initiation, incubation, and following hatch when successfully nesting females were tending to chicks. Mortalities in September coincided with dispersal and autumn migration. The survival estimate during the breeding season was greater among known failed nesters (trueSˆFAILED = 0.69) than females that nested successfully (trueSˆSUCCESSFUL = 0.53), indicating female greater sage‐grouse were exposed to greater mortality risk during incubation and brood‐rearing periods. Greater mortality risk during the breeding season (i.e., nesting and brood‐rearing) can have a major impact on greater sage‐grouse demography. Conservation and management efforts should focus on enhancing female greater sage‐grouse survival during the breeding and brood‐rearing season. © 2014 The Wildlife Society.

The influence of harvest timing on greater sage-grouse survival: A cautionary perspective

“…These results are driven, in part, by the relatively low reproductive success of female sage‐grouse. Although individual heterogeneity has been demonstrated for female sage‐grouse (Blomberg et al b , Caudill et al a , Davis et al ), reproductive success for sage‐grouse is also low in general (Connelly et al ) and in particular for this system. When coupled with lower survival due to reproductive costs (Blomberg et al b ), only a small proportion of hens with broods that are removed through additive harvest are expected to reproduce successfully again the following year, had they not been harvested.…”

“…However, compensation of harvest losses through increased post-harvest survival can occur at any point between the timing of harvest mortality and the birth of young the following spring; compensation need not be restricted to the winter. Recent work has demonstrated that sagegrouse survival may be reduced during the fall for both juveniles (Blomberg et al 2014, Caudill et al 2014b) and adult females (Blomberg et al 2013b, Davis et al 2014). This period of high non-harvest mortality occurs between August-October (Blomberg et al 2013a(Blomberg et al , b, 2014Caudill et al 2014b;Davis et al 2014), and sage-grouse hunting seasons typically begin in September and may continue into October (Table 1).…”

“…Recent work has demonstrated that sagegrouse survival may be reduced during the fall for both juveniles (Blomberg et al 2014, Caudill et al 2014b) and adult females (Blomberg et al 2013b, Davis et al 2014). This period of high non-harvest mortality occurs between August-October (Blomberg et al 2013a(Blomberg et al , b, 2014Caudill et al 2014b;Davis et al 2014), and sage-grouse hunting seasons typically begin in September and may continue into October (Table 1). In Nevada, mortality during the fall is associated primarily with increased predation risk in highdensity seasonal use areas, and predation accounts for 90% of mortalities (Blomberg et al 2013a).…”

Variable drivers of primary versus secondary nesting; density‐dependence and drought effects on greater sage‐grouse

“…Clutch size is generally high (species mean  7.4  0.8 SE; Schroeder et al 1999), but is variable among individuals and breeding attempts (may range from 3 to 12 eggs within a single population; Blomberg et al 2014a). Sage-grouse have intermediate annual survival probabilities (species mean for adult females  0.58; Taylor et al 2012), and female sage-grouse experience reproductive costs in the form of reduced survival following successful reproduction (Blomberg et al 2013a, Davis et al 2014, Dinkins et al 2014. Population growth in sage grouse is sensitive to both adult survival and some components of reproduction (e.g.…”

Effects of surgically implanted transmitters on reproduction and survival in mallards

“…Over the past 50 years, ecologists have used radiotelemetry to study survival, movement, and behavior of waterbirds, including shorebirds, cranes, grebes, loons, ducks, geese, swans, albatrosses, penguins, and alcids (e.g., Greenwood and Sargeant 1973, Klugman and Fuller 1990, Meyers et al 1998, Green et al 2004, Mulcahy et al 2011. In particular, telemetry-based breeding-season survival rates and habitat selection patterns have informed management and conservation practices of game birds (Cowardin et al 1985, Davis et al 2014, Howerter et al 2014, Gibson et al 2016. Usually, investigators make the fundamental assumption that capture and marking techniques do not bias parameters of interest such as behavior, reproductive effort, survival, or movement (Barron et al 2010).…”