Site Occupancy Dynamics of Northern Spotted Owls in the Eastern Cascades, Washington, USA, 1990–2003

2010 ◽  
Vol 74 (6) ◽  
pp. 1264-1274 ◽  
Author(s):  
Andrew J. Kroll ◽  
Tracy L. Fleming ◽  
Larry L. Irwin
Keyword(s):  
Site Occupancy ◽  
Occupancy Dynamics ◽  
Spotted Owls ◽  
Eastern Cascades ◽  
Northern Spotted Owls

Site Occupancy Dynamics of Northern Spotted Owls in the Eastern Cascades, Washington, USA, 1990-2003

2010 ◽  
Vol 74 (6) ◽  
pp. 1267-1274 ◽  
Author(s):  
ANDREW J. KROLL ◽  
TRACY L. FLEMING ◽  
LARRY L. IRWIN
Keyword(s):  
Site Occupancy ◽  
Occupancy Dynamics ◽  
Spotted Owls ◽  
Eastern Cascades ◽  
Northern Spotted Owls

Site occupancy dynamics of northern spotted owls in managed interior Douglas fir forests, California, USA, 1995-2009

2012 ◽  
Vol 76 (6) ◽  
pp. 1145-1152 ◽  
Author(s):  
Stuart L. Farber ◽  
Andrew J. Kroll
Keyword(s):  
Site Occupancy ◽  
Douglas Fir ◽  
Occupancy Dynamics ◽  
Spotted Owls ◽  
Northern Spotted Owls

MODELING OF SITE OCCUPANCY DYNAMICS FOR NORTHERN SPOTTED OWLS, WITH EMPHASIS ON THE EFFECTS OF BARRED OWLS

2005 ◽  
Vol 69 (3) ◽  
pp. 918-932 ◽  
Author(s):  
GAIL S. OLSON ◽  
ROBERT G. ANTHONY ◽  
ERIC D. FORSMAN ◽  
STEVEN H. ACKERS ◽  
PETER J. LOSCHL ◽  
...  
Keyword(s):  
Site Occupancy ◽  
Occupancy Dynamics ◽  
Spotted Owls ◽  
Northern Spotted Owls ◽  
Barred Owls

scholarly journals The past and future roles of competition and habitat in the range‐wide occupancy dynamics of Northern Spotted Owls

2019 ◽  
Vol 29 (3) ◽  
Author(s):  
Charles B. Yackulic ◽  
Larissa L. Bailey ◽  
Katie M. Dugger ◽  
Raymond J. Davis ◽  
Alan B. Franklin ◽  
...  
Keyword(s):  
The Past ◽  
Occupancy Dynamics ◽  
Spotted Owls ◽  
Northern Spotted Owls

Barred Owls reduce occupancy and breeding propensity of Northern Spotted Owl in a Washington old-growth forest

The Condor ◽  
2019 ◽  
Vol 121 (3) ◽  
Author(s):  
Anna O Mangan ◽  
Tara Chestnut ◽  
Jody C Vogeler ◽  
Ian K Breckheimer ◽  
Wendy M King ◽  
...  
Keyword(s):  
Endangered Species ◽  
Timber Harvest ◽  
Spotted Owl ◽  
Occupancy Dynamics ◽  
Old Growth Forest ◽  
Spotted Owls ◽  
Northern Spotted Owl ◽  
Northern Spotted Owls ◽  
Barred Owls ◽  
Breeding Propensity

Abstract Protected lands like national parks are important refuges for threatened and endangered species as environmental pressures on wildlife and their habitats increase. The Northern Spotted Owl (Strix occidentalis caurina), a species designated as threatened under the Endangered Species Act, occurs on public lands throughout the western United States including Mount Rainier National Park (MRNP), Washington. With virtually no history of timber harvest or large forest disturbance within MRNP boundaries since the park’s creation in 1899, MRNP provides an ideal place to evaluate potential impacts of climate change and invasive Barred Owls (Strix varia) on the Northern Spotted Owl. We used a multi-state, multi-season occupancy model to investigate how Northern Spotted Owl occupancy dynamics and breeding propensity are related to the presence of Barred Owls, local and regional weather, and habitat characteristics at MRNP from 1997 to 2016. Historical occupancy of Northern Spotted Owl breeding territories in MRNP has declined by 50% in the last 20 yr, and territory occupancy by breeding Northern Spotted Owls also decreased, reaching a low of 25% in 2016. Occupancy rates were higher on territories with steeper terrain and breeding rates were lower when Barred Owls were detected within historical territories. Our results also indicated that breeding propensity was higher when early nesting season temperatures during March and April were higher. In addition, the ability to detect breeding Northern Spotted Owls decreased when Barred Owls were present in the territory. Habitat variables from LiDAR were not correlated with Northern Spotted Owl occupancy dynamics, likely reflecting the dominance of old-growth forest in this protected park. This study illustrates the strong relationship between Barred Owls and Northern Spotted Owl demographics and breeding site selection in a landscape where habitat loss by timber harvest and fire has not occurred.

Factors Influencing the Distribution of Northern Spotted Owls in the Eastern Cascades, Washington

2011 ◽  
Vol 92 (1) ◽  
pp. 19-36 ◽  
Author(s):  
Craig Loehle ◽  
Larry Irwin ◽  
John Beebe ◽  
Tracy Fleming
Keyword(s):  
Factors Influencing ◽  
Spotted Owls ◽  
Eastern Cascades ◽  
Northern Spotted Owls

scholarly journals Evidence for recent population bottlenecks in northern spotted owls (Strix occidentalis caurina)

2009 ◽  
Vol 11 (3) ◽  
pp. 1013-1021 ◽  
Author(s):  
W. Chris Funk ◽  
Eric D. Forsman ◽  
Matthew Johnson ◽  
Thomas D. Mullins ◽  
Susan M. Haig
Keyword(s):  
Population Bottlenecks ◽  
Strix Occidentalis ◽  
Spotted Owls ◽  
Strix Occidentalis Caurina ◽  
Northern Spotted 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.

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