Habitat selection by spotted owls after a megafire in Yosemite National park

Schofield, Lynn N.; Eyes, Stephanie A.; Siegel, Rodney B.; Stock, Sarah

doi:10.1016/j.foreco.2020.118511

Cited by 10 publications

(10 citation statements)

References 45 publications

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“…Both larger owls (barred and great horned owls) were more likely to use unburned and low-severity areas compared to areas that burned more severely, though great horned owls had low overall use of the study area. We detected northern spotted owls very rarely in the study area and not at all in severely burned forests, a finding similar to other studies on northern spotted owls and other spotted owl subspecies (Rockweit et al 2017, Lesmeister et al 2018, Jones et al 2020b, Schofield et al 2020. Post-fire vegetation characteristics and, by extension, resource availability, change from year to year; thus, the landscape use relationships observed here over a single breeding season may change with time since fire (Smucker et al 2005, Sitters et al 2016.…”

Section: Discussionsupporting

confidence: 89%

Differential landscape use by forest owls two years after a mixed‐severity wildfire

et al. 2021

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Owls are important avian predators in forested systems, but little is known about landscape use by most forest-adapted owl species in environments impacted by mixed-severity wildfire. To better understand species-specific patterns of post-wildfire landscape use within an owl guild, we used passive acoustic monitoring using autonomous recording units. The technology is effective for multi-species surveys, especially if some species are rare, nocturnal, or difficult to detect by traditional means. In 2017, we surveyed the interior and adjacent unburned areas of a 10,700-ha mixed-severity wildfire that burned in 2015 in southwest Oregon. We used occupancy modeling to identify patterns of landscape use by five species of forest owls: barred owls (Strix varia), great horned owls (Bubo virginianus), western screech-owls (Megascops kennicottii), northern pygmy-owls (Glaucidium gnoma), and northern saw-whet owls (Aegolius acadicus). Our results showed a positive relationship between increasing fire severity and probability of use by western screech-owls and a similar but somewhat weaker relationship for northern pygmy-owls. Barred owls were rarely detected in severely burned areas and their use decreased with increased fire severity. We observed generally low landscape use for great horned owls, which decreased with increased fire severity and at higher elevations. Thus, four out of the five species appeared to use recently burned forests at different levels, with only northern saw-whet owls showing near-complete avoidance of the burned area. These findings increase our understanding of the basic ecology of each species and highlight the varied use of burned areas within this community. These previously undocumented patterns of landscape use in burned landscapes should provide insights to managers and policymakers in the Pacific Northwest as climate shifts, and fires may increase in size, frequency, and severity.

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Section: Discussionsupporting

confidence: 89%

Differential landscape use by forest owls two years after a mixed‐severity wildfire

et al. 2021

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“…If this assumption was incorrect, we expected it to have little effect on our analyses because only 6.5% of the burned area during our study was from fires <405 ha. We hypothesized that low‐ to moderate‐severity fire would have a positive or no effect on spotted owl occupancy and reproduction (Bond et al 2002, 2009, 2016; Schofield et al 2020; Kramer et al 2021) but that high‐severity fire (extent and patch size) would have a negative effect (Lee et al 2013; Jones et al 2016 a , 2020; Rockweit et al 2017). Because fire can affect spotted owl habitat for extended time periods, we estimated these covariates at 2 temporal scales: within the previous year and within the previous 5 years.…”

Section: Methodsmentioning

confidence: 99%

“…Conversely, historical fire regimes in seasonal dry forests throughout the spotted owl's range consisted of frequent fires that burned primarily at low and moderate severity with smaller patches of high‐severity fire (Stephens and Collins 2004, Safford and Stevens 2017). Consequently, owls appear to be well‐adapted to these regimes (Bond et al 2002, 2009; Jones et al 2020; Schofield et al 2020; Kramer et al 2021). To address the increasing threat of megafires, forest managers have implemented fuel‐reduction projects that employ techniques such as tree thinning, understory removal, and prescribed fire (Collins et al 2010, 2013).…”

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confidence: 99%

Population decline in California spotted owls near their southern range boundary

et al. 2022

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Species worldwide have begun to shift their range boundaries in response to climate change and other anthropogenic causes, with population declines at the trailing edge of a species' range often foreshadowing future changes in core parts of the range. Therefore, we analyzed a 30‐year (1991–2019) data set for the California spotted owl (Strix occidentalis occidentalis) near its southern range boundary in southern California, USA, that included the largest regional population (San Bernardino Mountains) to estimate trends in territory occupancy and reproduction. We then assessed how these demographic rates were affected by habitat, wildfire, fuel treatments, and climate. Mean occupancy declined from 0.82 to 0.39 during our study, whereas reproductive output showed no temporal trends ( truex ¯ = 0.65 young/occupied territory). Territory extinction (extirpation) rates were relatively low in territories with more large trees (≥50 cm dbh), and colonization increased strongly with large tree density for low‐elevation territories within the shrub‐woodland ecotype but not for higher‐elevation territories within mixed‐conifer forest. High‐severity wildfire had an adverse effect on occupancy: territory extinction rates steadily increased with the amount of high‐severity fire within an owl territory during the previous 10 years, while colonization declined to nearly zero when ≥40% of a territory burned at high‐severity during the previous 10 years. The effects of high‐severity fire were unlikely to be confounded with post‐fire fuel treatments, which primarily consisted of the removal, burning, or scattering of brush and small trees and snags (<40.6 cm dbh) and affected much smaller areas than high‐severity fire. Of the 40 territories that received fuel treatments within 10 years of a fire, only 3 of them had post‐fire fuel treatments that affected >5% of the territory, whereas average area burned at high severity for all 40 territories was 17%. Fuel treatments intended to modify fire behavior and reduce the likelihood of large, high‐severity fires led to increases in territory extinction and colonization such that their net effect on occupancy was minimal. Our simulations of occupancy dynamics indicated that high‐severity fire accounted for 9.6% of the observed decline in occupancy, whereas fuel treatments effectively accounted for none of the decline. Spotted owl reproductive output was lower at territories where fuel treatments occurred, but low‐ to moderate‐severity fire resulted in much larger, population‐level reductions in reproductive output (141 fewer young) from 2006–2019 than treatments (19 fewer young). Thus, the benefits of fuel treatments that reduce fire occurrence and severity appear to outweigh potential short‐term costs to spotted owls and their habitat. Because high‐severity fire only explained a modest amount of the long‐term occupancy decline and much of the decline occurred in the 1990s before large fires occurred, additional factors are likely adversely affecting the owl population and merit fur...

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“…One way to validate areas identified as fire refugia is to assess the persistence or (timely) return of target species postfire. For example, after the 2013 Rim Fire, spotted owls ( Strix occidentalis ) were recorded within certain areas of the fire perimeter at rates similar to those observed prefire, suggesting that forest characteristics remained consistent with owl habitat requirements (Schofield et al, 2020). See Table 2 for additional region‐specific tools and research products to identify and validate fire refugia.…”

Section: Process‐based Refugial Prioritiesmentioning

confidence: 98%

“…For example, long‐term data collection efforts tracking tree mortality factors, like the Yosemite Forest Dynamics Plot and the Sierra Nevada Forest Dynamics Plot Network (e.g., Das et al, 2016; Lutz, 2015), may be invoked to monitor the effectiveness of fire refugia for protecting forests. Evaluating persistence of target species within old growth forest postfire provides another means for monitoring refugia effectiveness (e.g., spotted owls: Schofield et al, 2020, Pacific fisher: Blomdahl et al, 2019). Monitoring that considers interactions between different process‐based refugial priorities could also be fruitful: for example, drought increases wildfire activity (Abatzoglou & Williams, 2016), and severity (i.e., kills more trees; van Mantgem et al, 2013), so hydrology‐focused monitoring, modeling, and mapping (e.g., Flint et al, 2014) may provide indirect indicators for fire refugia effectiveness when combined with fire data and/or stand structure and species composition data.…”

Section: Process‐based Refugial Prioritiesmentioning

confidence: 99%

Toward climate change refugia conservation at an ecoregion scale

Balantic

Adams

Gross

et al. 2021

Conservat Sci and Prac

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Climate change uncertainty poses serious challenges to conservation efforts. One emerging conservation strategy is to identify and conserve climate change refugia: areas relatively buffered from contemporary climate change that enable persistence of valued resources. This management paradigm may be pursued at broad scales by leveraging existing resources and placing them into a tangible framework to stimulate further collaboration that fosters management decision-making. Here, we describe a framework for moving toward operationalizing climate change refugia conservation at an ecoregion scale with an analysis for the Sierra Nevada ecoregion (CA, USA). Structured within the Climate Change Refugia Conservation Cycle, we identify a preliminary suite of conservation priorities for the ecoregion, and demonstrate how existing

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Habitat selection by spotted owls after a megafire in Yosemite National park

Cited by 10 publications

References 45 publications

Differential landscape use by forest owls two years after a mixed‐severity wildfire

Differential landscape use by forest owls two years after a mixed‐severity wildfire

Population decline in California spotted owls near their southern range boundary

Toward climate change refugia conservation at an ecoregion scale

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