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

Kroll, Andrew J.; Fleming, Tracy L.; Irwin, Larry L.

doi:10.2193/2009-429

Cited by 29 publications

(42 citation statements)

References 16 publications

(43 reference statements)

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“…The maximum number of surveys at any site in a year was 8, but both the median and mode number of visits across all sites each year was 6, so we truncated all withinyear survey histories at 6 surveys for this analysis to reduce the number of missing observations (Olson et al 2005, Kroll et al 2010). …”

Section: Spotted Owl Surveysmentioning

confidence: 99%

Previous year's reproductive state affects Spotted Owl site occupancy and reproduction responses to natural and anthropogenic disturbances

Lee

Bond

2015

The Condor

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Section: Spotted Owl Surveysmentioning

confidence: 99%

Previous year's reproductive state affects Spotted Owl site occupancy and reproduction responses to natural and anthropogenic disturbances

Lee

Bond

2015

The Condor

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“…Training included repeated exposure to all calls of each species, then placing the call-broadcast system in wetlands and blindly positioning observers at distances varying from 10-500 m. Training was conducted for each species at wetlands with different vegetative conditions (vegetation density and height) and during various weather conditions. We utilized a two-step modeling process by which covariates on p were modeled first while keeping ψ constant; the top model for p was then included in the models for ψ (Olsen et al 2005, Kroll et al 2010. When modeling ψ, we envisioned a hierarchical model selection framework similar to that described by Johnson (1980) in which birds are first selecting for broad-scale, landscape variables to establish home ranges and then select for microhabitat variables to establish feeding and nesting sites.…”

Section: Occupancy Modelsmentioning

confidence: 99%

Habitat Associations of Secretive Marsh Birds in Iowa

Harms

Dinsmore

2013

Wetlands

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Drastic losses of wetland habitats across North America over the past century have resulted in population declines of many marsh birds therefore emphasizing the need for proper management of remaining wetlands for the conservation of marsh birds. Our objective was to evaluate the probability of site occupancy of secretive marsh birds in Iowa in response to habitat variables at multiple scales. We conducted call-broadcast surveys for eight species of marsh birds at wetlands in Iowa from 16 May-15 July 2009 and from 20 April-10 July 2010. We utilized occupancy models in Program MARK to estimate site occupancy probability based on habitat covariates for four species with the most detections (Pied- . Wetland size had a positive effect on site occupancy for Least Bitterns, water depth positively affected site occupancy for Piedbilled Grebes and Least Bitterns, and percent cover of cattail positively affected site occupancy for Virginia Rails. Knowing habitat associations of secretive marsh birds in Iowa will allow us to provide guidance on wetland restoration and management decisions that will aid the conservation of these birds. Wetland size had a positive effect on site occupancy for Least Bitterns, water depth positively affected site occupancy for Pied-billed Grebes and Least Bitterns, and percent cover of cattail positively affected site occupancy for Virginia Rails. Knowing habitat associations of secretive marsh birds in Iowa will allow us to provide guidance on wetland restoration and management decisions that will aid the conservation of these birds.

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“…The general field methods for locating and banding of owls, determining sex and age, re-sighting previously marked owls, and determining productivity were described by Franklin et al (1996), and adaptation of this data for occupancy analysis was described by Olson et al (2005). Although these survey methods were designed to document survival and productivity, they also were well suited for determining occupancy rates , Kroll et al 2010.…”

Section: Survey Datamentioning

confidence: 99%

Transient dynamics of invasive competition: Barred Owls, Spotted Owls, habitat, and the demons of competition present

Dugger

Anthony

Andrews

2011

Ecological Applications

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Abstract. The recent range expansion of Barred Owls (Strix varia) into the Pacific Northwest, where the species now co-occurs with the endemic Northern Spotted Owl (Strix occidentalis caurina), resulted in a unique opportunity to investigate potential competition between two congeneric, previously allopatric species. The primary criticism of early competition research was the use of current species' distribution patterns to infer past processes; however, the recent expansion of the Barred Owl and the ability to model the processes that result in site occupancy (i.e., colonization and extinction) allowed us to address the competitive process directly rather than inferring past processes through current patterns. The purpose of our study was to determine whether Barred Owls had any negative effects on occupancy dynamics of nesting territories by Northern Spotted Owls and how these effects were influenced by habitat characteristics of Spotted Owl territories. We used single-species, multi-season occupancy models and covariates quantifying Barred Owl detections and habitat characteristics to model extinction and colonization rates of Spotted Owl pairs in southern Oregon, USA. We observed a strong, negative association between Barred Owl detections and colonization rates and a strong positive effect of Barred Owl detections on extinction rates of Spotted Owls. We observed increased extinction rates in response to decreased amounts of old forest at the territory core and higher colonization rates when old-forest habitat was less fragmented. Annual site occupancy for pairs reflected the strong effects of Barred Owls on occupancy dynamics with much lower occupancy rates predicted for territories where Barred Owls were detected. The strong Barred Owl and habitat effects on occupancy dynamics of Spotted Owls provided evidence of interference competition between the species. These effects increase the importance of conserving large amounts of contiguous, old-forest habitat to maintain Northern Spotted Owls in the landscape.

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

Cited by 29 publications

References 16 publications

Previous year's reproductive state affects Spotted Owl site occupancy and reproduction responses to natural and anthropogenic disturbances

Previous year's reproductive state affects Spotted Owl site occupancy and reproduction responses to natural and anthropogenic disturbances

Habitat Associations of Secretive Marsh Birds in Iowa

Transient dynamics of invasive competition: Barred Owls, Spotted Owls, habitat, and the demons of competition present

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