Spotted Owl Demography in the Central Sierra Nevada

2001 ◽  
Vol 65 (3) ◽  
pp. 425 ◽  
Author(s):  
Mark E. Seamans ◽  
R. J. Gutierrez ◽  
Christine A. Moen ◽  
M. Zachariah Peery
Keyword(s):  
Sierra Nevada ◽  
Spotted Owl

scholarly journals Habitat Selection in a Changing Environment: The Relationship Between Habitat Alteration and Spotted Owl Territory Occupancy and Breeding Dispersal

The Condor ◽  
2007 ◽  
Vol 109 (3) ◽  
pp. 566-576 ◽  
Author(s):  
Mark E. Seamans ◽  
R.J. Gutiérrez
Keyword(s):  
Habitat Selection ◽  
Sierra Nevada ◽  
Coniferous Forest ◽  
Canopy Cover ◽  
Habitat Alteration ◽  
Breeding Dispersal ◽  
Conifer Forest ◽  
Avian Behavior ◽  
Spotted Owl ◽  
The Relationship

Abstract Abstract. Understanding the effect of habitat alteration on avian behavior is important for understanding a species' ecology and ensuring its conservation. Therefore, we examined the relationship between Spotted Owl habitat selection and variation in habitat in the Sierra Nevada. We estimated habitat selection by modeling the probability of territory colonization (γ), territory extinction (ε), and breeding dispersal in relation to the amount of mature conifer forest within and among territories. Alteration of ≥20 ha of mature conifer forest (coniferous forest with >70% canopy cover dominated by medium [30.4–60.9 cm dbh] and large [>60.9 cm dbh] trees) within individual territories (n  =  66) was negatively related to territory colonization and positively related to breeding dispersal probability. Although territory extinction was negatively related to the amount of mature conifer forest, it was not clear whether this relationship was due to variation of mature conifer forest within or among territories. Although modeling results for territory colonization and extinction generally supported the hypothesis that individuals are “ideal” when selecting a habitat in the sense that they settle in the highest-quality site available, we did not find a clear benefit in terms of habitat quality for Spotted Owls that exhibited breeding dispersal.

scholarly journals Is “Fuel Reduction” Justified as Fire Management in Spotted Owl Habitat?

Birds ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 395-403
Author(s):  
Chad T. Hanson
Keyword(s):  
Forest Management ◽  
Sierra Nevada ◽  
Tree Mortality ◽  
Habitat Degradation ◽  
Fire Suppression ◽  
Fire Severity ◽  
Indirect Evidence ◽  
Fuel Reduction ◽  
Spotted Owl ◽  
California Spotted Owl

The California spotted owl is an imperiled species that selects mature conifer forests for nesting and roosting while actively foraging in the “snag forest habitat” created when fire or drought kills most of the trees in patches. Federal agencies believe there are excess surface fuels in both of these habitat conditions in many of California’s forests due to fuel accumulation from decades of fire suppression and recent drought-related tree mortality. Accordingly, agencies such as the U.S. Forest Service are implementing widespread logging in spotted owl territories. While they acknowledge habitat degradation from such logging, and risks to the conservation of declining spotted owl populations, agencies hypothesize that such active forest management equates to effective fuel reduction that is needed to curb fire severity for the overall benefit of this at-risk species. In an initial investigation, I analyzed this issue in a large 2020 fire, the Creek Fire (153,738 ha), in the southern Sierra Nevada mountains of California. I found that pre-fire snag density was not correlated with burn severity. I also found that more intensive forest management was correlated to higher fire severity. My results suggest the fuel reduction approach is not justified and provide indirect evidence that such management represents a threat to spotted owls.

Spotted owl foraging patterns following fuels treatments, Sierra Nevada, California

2018 ◽  
Vol 83 (2) ◽  
pp. 487-501 ◽  
Author(s):  
Claire V. Gallagher ◽  
John J. Keane ◽  
Paula A. Shaklee ◽  
H. Anu Kramer ◽  
Ross Gerrard
Keyword(s):  
Sierra Nevada ◽  
Foraging Patterns ◽  
Spotted Owl ◽  
Fuels Treatments

California Spotted Owl Occupancy On Mixed-Ownership Lands In the Sierra Nevada of California, 2012 Through 2016

2017 ◽  
Vol 98 (2) ◽  
pp. 101-116 ◽  
Author(s):  
Kevin N Roberts ◽  
William E Hall ◽  
Amanda J Shufelberger ◽  
Matthew A Reno ◽  
Michelle M Schroeder
Keyword(s):  
Sierra Nevada ◽  
Spotted Owl ◽  
California Spotted Owl

scholarly journals Wildfire impacts on California spotted owl nesting habitat in the Sierra Nevada

Ecosphere ◽  
2016 ◽  
Vol 7 (11) ◽  
Author(s):  
Scott L. Stephens ◽  
Jay D. Miller ◽  
Brandon M. Collins ◽  
Malcolm P. North ◽  
John J. Keane ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Nesting Habitat ◽  
Spotted Owl ◽  
California Spotted Owl

scholarly journals Early detection of rapid Barred Owl population growth within the range of the California Spotted Owl advises the Precautionary Principle

The Condor ◽  
2020 ◽  
Vol 122 (1) ◽  
Author(s):  
Connor M Wood ◽  
R J Gutiérrez ◽  
John J Keane ◽  
M Zachariah Peery
Keyword(s):  
Invasive Species ◽  
Population Growth ◽  
Sierra Nevada ◽  
Precautionary Principle ◽  
Grid Cells ◽  
Spotted Owl ◽  
The Precautionary Principle ◽  
California Spotted Owl ◽  
The Cost ◽  
Barred Owls

Abstract Biological invasions are most practical to manage when invasive species population densities are low. Despite a potentially narrow window of opportunity for efficient management, managers tend to delay intervention because the cost of prompt action is often high and resources are limited. The Barred Owl (Strix varia) invaded and colonized the entire range of the Northern Spotted Owl (S. occidentalis caurina), but insufficient population data contributed to delays in action until the Barred Owl posed an existential threat to the Spotted Owl. The leading edge of the Barred Owl expansion has since reached the Sierra Nevada, the core range of the California Spotted Owl (S. o. occidentalis). We conducted passive acoustic surveys within 400-ha grid cells across ~6,200 km2 in the northern Sierra Nevada and detected a 2.6-fold increase in Barred Owl site occupancy between 2017 and 2018, from 0.082 (85% confidence interval: 0.045–0.12) to 0.21 (0.14–0.28). The probability of Barred Owl site colonization increased with the amount of older forest, suggesting that Barred Owls are first occupying the preferred habitat of Spotted Owls. GPS-tagged Barred Owls (n = 10) generally displayed seasonal and interannual site fidelity over territories averaging 411 ha (range: 150–513 ha), suggesting that our occupancy estimates were not substantially upwardly biased by “double counting” individuals whose territories spanned multiple grid cells. Given the Barred Owl’s demonstrated threat to the Northern Spotted Owl, we believe our findings advise the Precautionary Principle, which posits that management actions such as invasive species removal should be taken despite uncertainties about, for example, true rates of population growth if the cost of inaction is high. In this case, initiating Barred Owl removals in the Sierra Nevada before the population grows further will likely make such action more cost-effective and more humane than if it is delayed. It could also prevent the extirpation of the California Spotted Owl from its core range.

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