scholarly journals Effects of experimental removal of Barred Owls on population demography of Northern Spotted Owls in Washington and Oregon—2017 progress report

2018 ◽  
Author(s):  
J. David Wiens ◽  
Katie M. Dugger ◽  
Damon B. Lesmeister ◽  
Krista E. Dilione ◽  
David C. Simon
Keyword(s):  
Progress Report ◽  
Population Demography ◽  
Experimental Removal ◽  
Spotted Owls ◽  
Northern Spotted Owls ◽  
Barred Owls

scholarly journals Social status, forest disturbance, and Barred Owls shape long-term trends in breeding dispersal distance of Northern Spotted Owls

The Condor ◽  
2019 ◽  
Vol 121 (4) ◽  
Author(s):  
Julianna M A Jenkins ◽  
Damon B Lesmeister ◽  
Eric D Forsman ◽  
Katie M Dugger ◽  
Steven H Ackers ◽  
...  
Keyword(s):  
Forest Disturbance ◽  
Dispersal Distance ◽  
Historical Study ◽  
Breeding Dispersal ◽  
Spotted Owls ◽  
Dispersal Distances ◽  
Dispersal Events ◽  
Northern Spotted Owls ◽  
Barred Owls ◽  
Over Time

Abstract Dispersal among breeding sites in territorial animals (i.e. breeding dispersal) is driven by numerous selection pressures, including competition and spatiotemporal variation in habitat quality. The scale and trend of dispersal movements over time may signal changing conditions within the population or on the landscape. We examined 2,158 breeding dispersal events from 694 male and 608 female individually marked Northern Spotted Owls (Strix occidentalis caurina) monitored over 28 yr on 7 study areas to assess the relative importance of individual (sex, experience), reproductive (annual productivity, mate availability), and environmental (forest alteration, presence of competitor) sources of variation in breeding dispersal distance. Median breeding dispersal distance was 3.17 km, with 99% of all breeding dispersal events <37 km. Mean annual dispersal distances increased by 2.43 km in Oregon and 9.40 km in Washington between 1990 and 2017, which coincided with increases in annual detections of nonnative Barred Owl (S. varia). Frequency of breeding dispersal events, both among and within individuals, also increased over time. Female owls moved farther than males (median of 3.26 and 3.10 km, respectively), and birds with less experience (territory tenure) moved farther than those with more experience. Owls that were single in the year prior to dispersal moved 13–31% farther than those paired prior to dispersal. The greatest environmental change occurring over the course of our study was the expansion of Barred Owl populations. Breeding dispersal distance was positively related to Barred Owls in the study area and disturbance within the originating territory. While it appears that social factors continue to be important drivers of breeding dispersal distance in Spotted Owls, increased competition from Barred Owls and habitat alteration have a contributing effect. Increased breeding dispersal distances should be of concern for conservation efforts and considered in population monitoring because changing dispersal behavior may lead to higher rates of mortality and/or emigration from historical study areas.

scholarly journals Does The Presence of Barred Owls Suppress the Calling Behavior of Spotted Owls?

The Condor ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 760-769 ◽  
Author(s):  
Michelle L. Crozier ◽  
Mark E. Seamans ◽  
R. J. GutiÉRrez ◽  
Peter J. Loschl ◽  
Robert B. Horn ◽  
...  
Keyword(s):  
Calling Behavior ◽  
Field Observations ◽  
Spotted Owl ◽  
Strix Occidentalis ◽  
Response Data ◽  
Strix Varia ◽  
Spotted Owls ◽  
Strix Occidentalis Caurina ◽  
Northern Spotted Owls ◽  
Barred Owls

Abstract Abstract Barred Owls (Strix varia) have expanded their range throughout the ranges of Northern (Strix occidentalis caurina) and California Spotted Owls (S. o. occidentalis). Field observations have suggested that Barred Owls may be behaviorally dominant to Spotted Owls. Therefore, we conducted a test of behavioral dominance by assessing responsiveness of Spotted Owls to conspecific calls when they were in the simulated presence (i.e., imitation of Barred Owl vocalizations) of a Barred Owl. We hypothesized that Spotted Owls would be less likely to respond to conspecific calls in areas where Barred Owls were common. We used a binary 2 × 2 crossover experimental design to examine male Spotted Owl responses at 10 territories randomly selected within two study areas that differed in abundance of Barred Owls. We also conducted a quasi experiment at four study areas using response data from any Spotted Owl (male or female) detected following exposure to Barred Owl calls. We inferred from the crossover experiment that the simulated presence of a Barred Owl might negatively affect Spotted Owl responsiveness. Both subspecies of Spotted Owl responded less to Spotted Owl calls after exposure to Barred Owl calls, Northern Spotted Owls responded less frequently in areas having higher numbers of Barred Owls, and California Spotted Owls responded less frequently than Northern Spotted Owls overall.

scholarly journals Barred owls and landscape attributes influence territory occupancy of northern spotted owls

2014 ◽  
Vol 78 (8) ◽  
pp. 1436-1443 ◽  
Author(s):  
Stan G. Sovern ◽  
Eric D. Forsman ◽  
Gail S. Olson ◽  
Brian L. Biswell ◽  
Margaret Taylor ◽  
...  
Keyword(s):  
Spotted Owls ◽  
Northern Spotted Owls ◽  
Barred Owls ◽  
Territory Occupancy ◽  
Landscape Attributes

Bringing Ethics to Wild Lives: Shaping Public Policy for Barred and Northern Spotted Owls

2018 ◽  
Vol 26 (2) ◽  
pp. 217-238 ◽  
Author(s):  
William S. Lynn
Keyword(s):  
Public Policy ◽  
The United States ◽  
Habitat Destruction ◽  
Stakeholder Group ◽  
Policy Dialogue ◽  
Spotted Owls ◽  
Key Factor ◽  
First Time ◽  
Northern Spotted Owls ◽  
Barred Owls

Abstract Ethics reviews are not part of environmental policy or wildlife management in the United States. This changed when, for the first time, the US Fish and Wildlife Service conducted such a review with respect to the barred and northern spotted owls. Spotted owls are endangered throughout their range by a variety of anthropogenic and natural forces. The interspecific competition between barred and spotted owls is a key factor second only to habitat destruction. A proposed lethal experiment to remove barred owls raised ethical concerns among wildlife agencies, citizens, and advocacy groups. Seeking to better understand these concerns, the Service created the Barred Owl Stakeholder Group. Using an innovative method and instrument in the form of an ethics-based policy dialogue and an ethics brief, the stakeholder group explored the ethical dimensions of the removal experiment. This process holds lessons for how public policy can bring ethics to bear on wild lives.

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