Effects of Barred Owl (Strix Varia) Removal on Population Demography of Northern Spotted Owls (Strix Occidentalis Caurina) in Washington and Oregon, 2015-18 PDF Download
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Author: J. David Wiens
Publisher:
ISBN:
Category : Barred owl
Languages : en
Pages : 17
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Book Description
Author: J. David Wiens
Publisher:
ISBN:
Category : Barred owl
Languages : en
Pages : 17
Get Book Here
Book Description
Author: J. David Wiens
Publisher:
ISBN:
Category : Barred owl
Languages : en
Pages : 16
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Book Description
Evidence indicates that competition with newly established barred owls (Strix varia) is causing rapid declines in populations of northern spotted owls (Strix occidentalis caurina), and that the long-term persistence of spotted owls may be in question without additional management intervention. A pilot study in California showed that lethal removal of barred owls in combination with habitat conservation may be able to slow or even reverse population declines of spotted owls at local scales, but it remains unknown whether similar results can be obtained in larger areas with different forest conditions and where barred owls are more abundant. In 2015, we implemented a before-after-control-impact (BACI) experimental design on two study areas in Oregon and Washington with at least 20 years of pre-treatment demographic data on spotted owls to determine if removal of barred owls can improve population trends of spatially associated spotted owls. Here we provide an overview of our research accomplishments and preliminary results in Oregon and Washington in 2015.
Author: Eric D. Forsman
Publisher: Univ of California Press
ISBN: 0520270088
Category : Medical
Languages : en
Pages : 120
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Conclusions, and Recommendations P.75
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 480
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Author: Elizabeth G. Kelly
Publisher:
ISBN:
Category : Animal migration
Languages : en
Pages : 156
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Since their range expansion into the Pacific Northwest, anecdotal evidence suggests that northern barred owls (Strix varia varia) may be displacing northern spotted owls (Strix occidentalis caurina). My objectives were to characterize barred owl distribution and population increase in Oregon, investigate spotted owl territory performance before and after barred owl detection, and document cases of hybridization between barred owls and spotted owls. Between 1974-1998, 706 unique barred owl territories were reported in Oregon. At five spotted owl demographic study areas in Washington and Oregon, barred owl detections increased rapidly between 1987-1999. After barred owls were detected within 0.80 km of the spotted owl territory center, occupancy of spotted owls declined, and there was a significant likelihood of spotted owl displacement when barred owls were either currently or previously present. When barred owls were detected between 0.81-2.40 km from the spotted owl territory center, there was no difference in mean occupancy of spotted owls after barred owls were detected, and spotted owl detection rates when barred owls were currently or previously present were not significantly different from territories without barred owls. There was no effect on spotted owl reproductive performance after barred owls were detected within 0.80 km or between 0.8 1-2.40 km of the territory center. When barred owls were detected within 0.80 km of a spotted owl territory center, 46% of the spotted owls moved> 0.80 km and 39% were never found again. In comparison, at territories without barred owls, only 21% of spotted owls moved> 0.80 km, and only 11% disappeared completely. When barred owls were detected between 0.81-2.40 km from the territory center there was no difference in rates of movement or disappearance of spotted owls between territories with and without barred owls. Reports of hybridization between spotted owls and barred owls are uncommon. Between 1974 and 1999, 24 adult and 26 juvenile hybrids were confirmed in Washington and Oregon. Data from this study suggest that barred owls pose a threat to spotted owls but it is too soon to predict whether trends observed in this study will continue, or will spread to other areas.
Author: Brian R. Chapman
Publisher: John Wiley & Sons
ISBN: 1118971566
Category : Science
Languages : en
Pages : 346
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Book Description
North America contains an incredibly diverse array of natural environments, each supporting unique systems of plant and animal life. These systems, the largest of which are biomes, form intricate webs of life that have taken millennia to evolve. This richly illustrated book introduces readers to this extraordinary array of natural communities and their subtle biological and geological interactions. Completely revised and updated throughout, the second edition of this successful text takes a qualitative, intuitive approach to the subject, beginning with an overview of essential ecological terms and concepts, such as competitive exclusion, taxa, niches, and succession. It then goes on to describe the major biomes and communities that characterize the rich biota of the continent, starting with the Tundra and continuing with Boreal Forest, Deciduous Forest, Grasslands, Deserts, Montane Forests, and Temperature Rain Forest, among others. Coastal environments, including the Laguna Madre, seagrasses, Chesapeake Bay, and barrier islands appear in a new chapter. Additionally, the book covers many unique features such as pitcher plant bogs, muskeg, the polar ice cap, the cloud forests of Mexico, and the LaBrea tar pits. “Infoboxes” have been added; these include biographies of historical figures who provided significant contributions to the development of ecology, unique circumstances such as frogs and insects that survive freezing, and conservation issues such as those concerning puffins and island foxes. Throughout the text, ecological concepts are worked into the text; these include biogeography, competitive exclusion, succession, soil formation, and the mechanics of natural selection. Ecology of North America 2e is an ideal first text for students interested in natural resources, environmental science, and biology, and it is a useful and attractive addition to the library of anyone interested in understanding and protecting the natural environment.
Author: J. David Wiens
Publisher:
ISBN:
Category : Barred owl
Languages : en
Pages : 23
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Author: J. David Wiens
Publisher:
ISBN:
Category : Barred owl
Languages : en
Pages : 23
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Author: Robert Gene Anthony
Publisher:
ISBN:
Category : Northern spotted owl
Languages : en
Pages : 52
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Book Description
"We analyzed demographic data from northern spotted owls (Strix occidentalis caurina) from 12 study areas in Washington, Oregon, California for 1985-2003. The purpose of our analyses was to provide an assessment of the status and trends of northern spotted owl populations throughout most of their geographic range"--Page 2.
Author:
Publisher:
ISBN:
Category : Endangered species
Languages : en
Pages : 396
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