Forest Structure Within Barred Owl (Strix varia) Home Ranges in the Eastern Cascade Range, Washington

Singleton, Peter H.

doi:10.3356/rapt-49-02-129-140.1

Cited by 5 publications

(5 citation statements)

References 165 publications

(280 reference statements)

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“…Terrain conditions were identified as influential for habitat use by barred owls in the eastern Cascade Range of Washington 14 and from prior analyses in our study area 9 . We found that slope differentiated fine-scale resource use between species, where spotted owls used steeper slopes compared to barred owls.…”

Section: Discussionmentioning

confidence: 93%

Three-dimensional partitioning of resources by congeneric forest predators with recent sympatry

Jenkins

Lesmeister

Wiens

et al. 2019

Sci Rep

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Coexistence of ecologically similar species can be maintained by partitioning along one or more niche axes. Three-dimensional structural complexity is central to facilitating resource partitioning between many forest species, but is underrepresented in field-based studies. We examined resource selection by sympatric northern spotted owls ( Strix occidentalis caurina ), a threatened species under the US Endangered Species Act, and nonnative barred owls ( S . varia ) in western Oregon, USA to explore the relative importance of canopy heterogeneity, vertical complexity of forest, and abiotic features to resource selection and identify potential differences that may facilitate long-term coexistence. We predicted that within home range selection of understory densities, measured with airborne lidar, would differ between species based on proportional differences in arboreal and terrestrial prey taken by each owl species. We used discrete choice models and telemetry data from 41 spotted owls and 38 barred owls monitored during 2007–2009 and 2012–2015. Our results suggested that while both species used tall canopy areas more often than low canopy areas, spotted owls were more commonly found in areas with lower tree cover, more developed understory, and steeper slopes. This is the first evidence of fine-scale partitioning based on structural forest properties by northern spotted owls and barred owls.

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Section: Discussionmentioning

confidence: 93%

Three-dimensional partitioning of resources by congeneric forest predators with recent sympatry

Jenkins

Lesmeister

Wiens

et al. 2019

Sci Rep

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“…For example, forest densification, increased canopy cover and layering, and compositional shifts toward shade-tolerant tree species have benefited a number of species (e.g., northern goshawk (Accipiter gentilis), fisher, marten (Martes caurina), barred owl (Strix varia), CASPO (Strix occidentalis occidentalis), and the northern spotted owl (Brown et al, 2004;Gaines et al, 2010aGaines et al, , 2010bNoss et al, 2006;Singleton, 2015;Spies et al, 2006Spies et al, , 2010Zielinski, 2014;Keane, 2014). These novel habitats may be degraded by thinning and prescribed fire treatments that seek to create more open forests with LOEST.…”

Section: Strategy 7: Integrating Restoration With Late-successional Fmentioning

confidence: 99%

Tamm Review: Management of mixed-severity fire regime forests in Oregon, Washington, and Northern California

Hessburg

Spies

Perry

et al. 2016

Forest Ecology and Management

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a b s t r a c tIncreasingly, objectives for forests with moderate-or mixed-severity fire regimes are to restore successionally diverse landscapes that are resistant and resilient to current and future stressors. Maintaining native species and characteristic processes requires this successional diversity, but methods to achieve it are poorly explained in the literature. In the Inland Pacific US, large, old, early seral trees were a key historical feature of many young and old forest successional patches, especially where fires frequently occurred. Large, old trees are naturally fire-tolerant, but today are often threatened by dense understory cohorts that create fuel ladders that alter likely post-fire successional pathways. Reducing these understories can contribute to resistance by creating conditions where canopy trees will survive disturbances and climatic stressors; these survivors are important seed sources, soil protectors, and critical habitat elements. Historical timber harvesting has skewed tree size and age class distributions, created hard edges, and altered native patch sizes. Manipulating these altered forests to promote development of larger patches of older, larger, and more widely-spaced trees with diverse understories will increase landscape resistance to severe fires, and enhance wildlife habitat for underrepresented conditions.Closed-canopy, multi-layered patches that develop in hot, dry summer environments are vulnerable to droughts, and they increase landscape vulnerability to insect outbreaks and severe wildfires. These same patches provide habitat for species such as the northern spotted owl, which has benefited from increased habitat area. Regional and local planning will be critical for gauging risks, evaluating trade-offs, and restoring dynamics that can support these and other species. The goal will be to manage for heterogeneous landscapes that include variably-sized patches of (1) young, middle-aged, and old, closedcanopy forests growing in upper montane, northerly aspect, and valley bottom settings, (2) a similar diversity of open-canopy, fire-tolerant patches growing on ridgetops, southerly aspects, and lower montane settings, and (3) significant montane chaparral and grassland areas. Tools to achieve this goal http://dx

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“…Recent studies suggest that the first outcome, competitive exclusion of northern spotted owls by barred owls throughout much of their historical range, has already begun to occur (Wiens et al , Yackulic et al , Dugger et al ). Compared with spotted owls, barred owls are slightly larger (Gutiérrez et al ), have more diverse diets (Hamer et al , Wiens et al ), and use a broader range of forest conditions for nesting (Herter and Hicks , Pearson and Livezey , Livezey ) and foraging (Hamer et al , Singleton et al , Wiens et al , Singleton ). Barred owls also have greater survival and reproduction, and tend to use much smaller home ranges than spotted owls (Hamer et al , Singleton et al , Wiens et al ).…”

Section: Hypothesized Effects Of Barred Owlsmentioning

confidence: 99%

Potential trophic cascades triggered by the barred owl range expansion

et al. 2016

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Recently, the barred owl (Strix varia) has expanded its range into the Pacific Northwest of the United States resulting in pronounced effects on the demography and behavior of the northern spotted owl (S. occidentalis caurina). The range expansion has brought together historically allopatric species, creating the potential for significant changes in the avian predator community with possible cascading effects on food-web dynamics. The adverse effects of the barred owl on the behavior and demography of the northern spotted owl are well-documented, but little is known about the immediate and long-term effects changes in the predator community may have on native species composition and ecosystem processes. Based on northern spotted owl and barred owl selection for diet and habitat resources, there is a potential for trophic cascades within the region's predator and prey communities, differing responses by their shared and unique prey species, and possible direct and indirect effects on ecosystem processes. We explored the possible ecological consequences of the barred owl range expansion to wildlife communities of the Pacific Northwest based on the theoretical underpinnings of predator-prey relationships, interspecific competition, intraguild predation, and potential cascading trophic interactions. Negative effects on fitness of northern spotted owls because of interspecific competition with barred owls are strong selection forces that may contribute to the regional extinction of the northern spotted owl. In addition, we posit that shared prey species and those uniquely consumed by barred owls, along with other competing native predators, may experience changes in behavior, abundance, and distribution as a result of increased rates of predation by rapidly expanding populations of barred owls.

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Forest Structure Within Barred Owl (Strix varia) Home Ranges in the Eastern Cascade Range, Washington

Cited by 5 publications

References 165 publications

Three-dimensional partitioning of resources by congeneric forest predators with recent sympatry

Three-dimensional partitioning of resources by congeneric forest predators with recent sympatry

Tamm Review: Management of mixed-severity fire regime forests in Oregon, Washington, and Northern California

Potential trophic cascades triggered by the barred owl range expansion

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