Greater sage‐grouse vital rates after wildfire

Abstract

Greater sage‐grouse (Centrocercus urophasianus) have been subject to long‐term and continuing declines in population and habitat since European settlement of western North America. Increased wildfire activity constitutes a primary threat to the species in western portions of their range, with documented declines in wildfire‐affected populations. Following a 187,000‐ha wildfire in southeastern Oregon and northern Nevada, USA, we used global positioning system (GPS) telemetry to monitor nest initiation, nest survival, nesting habitat, and adult survival of female sage‐grouse during 2013 and 2014. We used known‐fate models in Program MARK to estimate daily nest survival and monthly adult survival in relation to temporal patterns, physiological characteristics of females, and habitat and land‐cover characteristics. We assessed habitat characteristics using geographic information system (GIS)‐derived measures of post‐fire habitat condition and land cover. Nest initiation rate following the fire was comparable to that observed in unaltered habitat. We observed nesting rates of 90% and 100% during 2013 and 2014, respectively, and renesting rates of 23% and 57% during the same years. Daily nest survival was consistently low in comparison to rates observed in concurrent studies in the region, for first nests during both years, and for second nests during 2013, but survival markedly increased for second nests during 2014. Sage‐grouse generally did not leave the fire perimeter to nest, with 64% and 73% of nests located in the fire boundary during 2013 and 2014, respectively. Approximately 27% of nests were located in burned habitat during 2013, and 20% of nests in 2014 were located in burned habitat. Adult survival varied by month, and although patterns of monthly survival were similar between years, monthly survival rates were significantly reduced from the beginning of the study through the end of the first post‐fire growing season. Our results indicate that sage‐grouse continue to use fire‐affected habitat in the years immediately following wildfire and sage‐grouse experienced lower nest survival and adult female survival than other populations during the same period. © 2018 The Wildlife Society.

The potential importance of unburned islands as refugia for the persistence of wildlife species in fire‐prone ecosystems

“…These factors may enhance the successful breeding of sage‐grouse at leks in unburned islands. Although movement between leks is uncommon (e.g., Fremgen et al, ; Gibson, Blomberg, Atamian, & Sedinger, ), male sage‐grouse may experience lower lek fidelity in disturbed and fragmented landscapes as compared to intact habitats (Foster et al, ; Schroeder & Robb, ). As a result, the apparent high persistence within unburned islands may also be partly caused by postfire movements of male sage‐grouse from burned leks to unburned island leks.…”

“…Few studies have investigated the effect of fire and fire refugia on temporal dynamics of wildlife populations like the sage‐grouse (Coates et al, ; Foster et al, ; Robinson et al, ). The results of our study therefore constitute some of the first quantified evidence of the importance of unburned islands in the persistence and recovery of wildlife populations, using time series data in relation to specific fire events.…”

“…Hence, unburned islands could potentially also function as ecological traps (Gates & Gysel, 1978) because they force sage-grouse to select lower-quality habitats that have increased rates of predation and fitness costs (Battin, 2004). This effect may be exacerbated by the high site fidelity of sage-grouse to leks (Fremgen et al, 2017), although some other research suggests that nest site fidelity is reduced when sagegrouse inhabit disturbed and fragmented landscapes compared to intact habitats (e.g., Foster et al, 2019;Schroeder & Robb, 2003).…”

“…Therefore, the extent and characteristics of sagebrush habitat are directly linked to the persistence of this species (Knick, Hanser, & Preston, ). Observed declines in sage‐grouse populations following wildfire are most likely caused by reduced survival and reproduction through loss of habitat, rather than due to emigration away from fire‐affected areas (Coates et al, ; Foster, Dugger, Hagen, & Budeau, ).…”

“…Observed declines in sage-grouse populations following wildfire are most likely caused by reduced survival and reproduction through loss of habitat, rather than due to emigration away from fire-affected areas (Coates et al, 2015;Foster, Dugger, Hagen, & Budeau, 2019).…”