Acute and lagged fitness consequences for a sagebrush obligate in a post mega‐wildfire landscape

Abstract

Species responses to disturbance influence their extinction risks. Greater sage‐grouse (Centrocercus urophasianus) are bioindicators of sagebrush ecosystem health and the loss of sagebrush (Artemisia spp.) due to wildfire, can cause long‐term declines in sage‐grouse populations and other sagebrush obligate species. We examined the demographic response of a greater sage‐grouse population following a mega‐wildfire using stochastic age‐structured female‐based matrix models over 6 years (2013–2018). Notably, chick survival (range = 0.18–0.38) and female survival (yearling range: 0.20–0.68; adult range: 0.27–0.75) were low compared to values reported for greater sage‐grouse in other parts of their distribution. Greater sage‐grouse displayed variation in demographic tactics after the fire; however, adult female survival explained most of the variation in λ during each year, which reflected a declining population in 3 of 6 years with more uncertainty observed in 2015 when populations may have been increasing, and 2017 and 2018, when populations may have been declining. The continued annual population decline observed since 2016 suggested there were additional strong environmental impacts that may have been compounded by the fire effects, prolonging recovery of greater sage‐grouse. Our results support others that reported negative effects to greater sage‐grouse demographics from broad‐scale fire and provide a baseline for understanding how this species responds to loss of sagebrush cover based on their life history strategy.

What do you mean, ‘megafire’?

“…Of those studies that specified size thresholds for megafires, the most commonly used threshold was ≥ 10,000 ha (41%, 18/44) (Figure 3). The second most commonly specified size thresholds were in the 10,001–50,000 ha range (Figure 3), specified in 32% (14/44) of definitions (e.g., Anthony et al., 2021; Barton & Poulos, 2019; Maezumi et al., 2018). The lowest thresholds identified were 100 ha (Fidelis et al., 2018) and 500 ha (Alló & Loureiro, 2020; Mancini et al., 2017).…”

The importance of habitat type and historical fire regimes in arthropod community response following large‐scale wildfires

“…This may be driven by the openness created by fire in scrub habitat that prompts the establishment of non‐native grasses and creates habitat that promotes the establishment of species less common in scrub. Species that serve as bioindicators in scrub habitat, such as the greater sage‐grouse ( Centrocercus urophasianus ), are strongly affected by large‐scale wildfires, possibly because of increases in predator populations that benefit from the new vegetation (Anthony et al., 2022). Species that must re‐colonize following fire, such as aerial pollinators, have been found to take the longest to recover in California scrublands, and are significantly more sensitive to changes in fire characteristics (van Mantgem et al., 2015); while the patchy nature of historical fire regimes in scrublands could provide refugia and pathways for recolonization, large‐scale wildfires will decimate intermediate habitat and create a large‐scale hostile matrix.…”

Relationship of greater sage‐grouse to natural and assisted recovery of key vegetation types following wildfire: insights from scat

“…Previous observations and research studies of GRSG revealed that GRSG populations decline after fire, and that the declines are related to (1) the loss of sagebrush cover and increases in exotic annual grass cover (Coates et al 2016) and (2) a habitual return of GRSG to their seasonal ranges after fire despite severe habitat alteration and degradation, resulting in lower survival and productivity (Foster et al 2019; O'Neil et al 2020; Steenvoorden et al 2020; Anthony et al 2021 a ). Native vegetation, particularly perennials, is needed by GRSG for hiding cover to avoid predation and dietary and energy demands, especially during the spring GRSG reproduction season (Coates & Delehanty 2010; Conover et al 2010; Anthony et al 2021 b ).…”