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J David Wiens

My research interest include avian ecology, conservation of threatened and endangered species, population dynamics of forest and rangeland raptor species

Education and Certifications

  • Ph.D., Wildlife Science, Oregon State University, Corvallis, OR (2012)

  • M.S., Ecology, Colorado State University, Fort Collins, CO (2004)

  • B.S., Environmental Science, Northern Arizona University, Flagstaff, AZ (1993)

Science and Products

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Northern spotted owl flying

Effects of Experimental Removal of Barred Owls on Population Demography of Northern Spotted Owls in the Pacific Northwest

Barred owls (Strix varia) have expanded their geographic range from eastern to western North America, and their newly expanded range now completely overlaps that of the federally threatened northern spotted owl (S. occidentalis caurina; Gutiérrez et al. 2007, Livezey 2009, USFWS 2013). Evidence from long-term demographic studies indicates that the presence of barred owls has contributed...
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Forest and Rangeland Ecosystem Science Center
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Effects of Experimental Removal of Barred Owls on Population Demography of Northern Spotted Owls in the Pacific Northwest

Barred owls (Strix varia) have expanded their geographic range from eastern to western North America, and their newly expanded range now completely overlaps that of the federally threatened northern spotted owl (S. occidentalis caurina; Gutiérrez et al. 2007, Livezey 2009, USFWS 2013). Evidence from long-term demographic studies indicates that the presence of barred owls has contributed...
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Forest in flames. Smoke billowing

Fire Refugia in Old-Growth Forests: Predicting Habitat Persistence to Support Land Management in an Era of Rapid Global Change

Mature, old-growth forests in the Pacific Northwest provide critical habitat for threatened and endangered species, including the northern spotted owl and marbled murrelet. Dominated by large Douglas-firs and western hemlocks, these established forests range in age from 200 to 1,000 years old. Yet wildfire activity is increasing across western North America, heightening concerns about severe fires
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Climate Adaptation Science Centers, Climate Adaptation Science Center
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Fire Refugia in Old-Growth Forests: Predicting Habitat Persistence to Support Land Management in an Era of Rapid Global Change

Mature, old-growth forests in the Pacific Northwest provide critical habitat for threatened and endangered species, including the northern spotted owl and marbled murrelet. Dominated by large Douglas-firs and western hemlocks, these established forests range in age from 200 to 1,000 years old. Yet wildfire activity is increasing across western North America, heightening concerns about severe fires
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Forest in flames. Smoke billowing

Fire Refugia in Old-Growth Forests: Predicting Habitat Persistence to Support Land Management in an Era of Rapid Global Change

Mature, old-growth forests in the Pacific Northwest provide critical habitat for threatened and endangered species, including the northern spotted owl and marbled murrelet. Dominated by large Douglas-firs and western hemlocks, these established forests range in age from 200 to 1,000 years old. Yet wildfire activity is increasing across western North America, heightening concerns about severe fires
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Climate Adaptation Science Centers, Climate Adaptation Science Center
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Fire Refugia in Old-Growth Forests: Predicting Habitat Persistence to Support Land Management in an Era of Rapid Global Change

Mature, old-growth forests in the Pacific Northwest provide critical habitat for threatened and endangered species, including the northern spotted owl and marbled murrelet. Dominated by large Douglas-firs and western hemlocks, these established forests range in age from 200 to 1,000 years old. Yet wildfire activity is increasing across western North America, heightening concerns about severe fires
Learn More
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Image: Barred Owl

Threat of Invasive Barred Owls to Northern Spotted Owls and their Habitats

As an apex predator and fiercely territorial invader, barred owls at high densities have the potential to affect a variety of native wildlife through competition, niche displacement, and predation. Such impacts may be especially problematic for conservation of the federally threatened northern spotted owl, whose populations have continued to decline despite widespread protection of old forest...
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Forest and Rangeland Ecosystem Science Center
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Threat of Invasive Barred Owls to Northern Spotted Owls and their Habitats

As an apex predator and fiercely territorial invader, barred owls at high densities have the potential to affect a variety of native wildlife through competition, niche displacement, and predation. Such impacts may be especially problematic for conservation of the federally threatened northern spotted owl, whose populations have continued to decline despite widespread protection of old forest...
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USGS science for a changing world

Golden Eagles and Renewable Energy Development in the Western U.S.

Development of wind-power and solar facilities is expected to increase dramatically in areas occupied by golden eagles in the western U.S. Renewable energy development in areas used by golden eagles poses a unique challenge to natural resource managers because of this species’ vulnerability to collisions with wind turbines and sensitivity to changes in human land-use.
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Energy & Wildlife, Forest and Rangeland Ecosystem Science Center
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Golden Eagles and Renewable Energy Development in the Western U.S.

Development of wind-power and solar facilities is expected to increase dramatically in areas occupied by golden eagles in the western U.S. Renewable energy development in areas used by golden eagles poses a unique challenge to natural resource managers because of this species’ vulnerability to collisions with wind turbines and sensitivity to changes in human land-use.
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If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.

Detection/non-detection data on territorial pairs of golden eagles in coastal southern California, 2016-2017

This dataset contains detection-nondetection data for territorial pairs of Golden Eagles at survey sites randomly selected from a grid of equal-sized (13.9 km2) hexagonal sample cells overlaid across the region of interest in Coastal Southern California during 2016 and 2017. We partitioned surveys within seasons based on approximate transition dates for stages in the breeding cycle of golden eagle
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Forest and Rangeland Ecosystem Science Center

Anticoagulant rodenticide exposure in Barred Owls (Strix varia) collected in Washington and Oregon 2015-2017

This dataset includes anticoagulant rodenticide (AR) screening results of 40 Barred Owls (Strix varia) collected in forested landscapes of Washington and Oregon from 2015-2017. Liver tissue was collected from each owl and screened for exposure to eight AR compounds, including 4 first-generation ARs (warfarin, diphacinone, chlorophacinone, and coumachlor), and 4 second-generation ARs (brodifacoum,
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Forest and Rangeland Ecosystem Science Center

Count and detection-nondetection survey data of barred owls (Strix varia) in historical breeding territories of Northern Spotted Owls (Strix occidentalis caurina) in the Oregon Coast Range, 1995-2016

This dataset contains count and detection-nondetection data of Barred Owls from 106 historical breeding territories of Northern Spotted Owl territories (i.e. sites) in the Oregon Coast Ranges from 1995 to 2016. Data collected from 1995 to 2014 are partitioned into 2-week periods from 1 March - 31 August each year, totaling 12 possible sampling periods per year. Data collected from 2015 and 2016 ar
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Forest and Rangeland Ecosystem Science Center

If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.

Filter Total Items: 24

Golden eagle population surveys in the vicinity of the Altamont Pass Wind Resource Area, California, 2014–21

Golden Eagles (Aquila chrysaetos) are among the highest profile species killed by collisions with wind turbines at the Altamont Pass Wind Resource Area (APWRA) in the northern Diablo Range of west-central California. Understanding the distribution, site occupancy, and nesting status of eagles near the APWRA is needed to identify and minimize possible population-level impacts. We established a broa
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Invader removal triggers competitive release in a threatened avian predator

Invasive species can cause extinctions of native species and widespread biodiversity loss. Invader removal is a common management response, but the use of long-term field experiments to characterize effectiveness of removals in benefitting impacted native species is rare. We used a large-scale removal experiment to investigate the demographic response of a threatened native species, the northern s
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Ecosystems, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Patuxent Wildlife Research Center, Southwest Biological Science Center

Conspecific and congeneric interactions shape increasing rates of breeding dispersal of northern spotted owls

Breeding dispersal, the movement from one breeding territory to another, is rare for philopatric species that evolved within relatively stable environments, such as the old-growth coniferous forests of the Pacific Northwest. Although dispersal is not inherently maladaptive, the consequences of increased dispersal on population dynamics in populations whose historical dispersal rates are low could
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Distribution and abundance of Aquila chrysaetos (golden eagles) in East Contra Costa County Habitat Conservation Plan/Natural Community Conservation Plan area, California

The East Contra Costa County Habitat Conservation Plan/Natural Community Conservation Plan (HCP/NCCP) Preserve System was designed to protect and enhance ecological diversity and function in eastern Contra Costa County, California. Aquila chrysaetos (golden eagle) is a special-status species expected to benefit from biological goals of the HCP/NCCP. As part of a broader study, we estimated site-oc
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Effects of barred owl (Strix varia) removal on population demography of northern spotted owls (Strix occidentalis caurina) in Washington and Oregon—2019 annual report

Strix occidentalis caurina (northern spotted owl; hereinafter referred to as spotted owl) have rapidly declined throughout the subspecies’ geographic range. Competition with invading Strix varia (barred owl) has been identified as an immediate cause of those declines. A pilot study in California showed that removal of barred owls coupled with conservation of suitable habitat conditions can slow or
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Anticoagulant rodenticides in Strix owls indicate widespread exposure in west coast forests

Exposure of nontarget wildlife to anticoagulant rodenticides (AR) is a global conservation concern typically centered around urban or agricultural areas. Recently, however, the illegal use of ARs in remote forests of California, USA, has exposed sensitive predators, including the federally threatened northern spotted owl (Strix occidentalis caurina). We used congeneric barred owls (S. varia) as a
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Effects of experimental removal of Barred Owls on population Demography of Northern Spotted Owls in Washington and Oregon—2018 Progress Report

Populations of Northern Spotted Owls (Strix occidentalis caurina; herineafter referred to as Spotted Owl) have declined throughout the subspecies’ geographic range. Evidence indicates that competition with invading Barred Owls (S. varia) has contributed significantly to those declines. A pilot study in California showed that removal of Barred Owls coupled with conservation of suitable habitat cond
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Ecosystems, Wildlife Program, Forest and Rangeland Ecosystem Science Center

Geographic variation in natal dispersal of Northern Spotted Owls over 28 years

The most recent comprehensive estimates of Northern Spotted Owl (Strix occidentalis caurina) natal dispersal distances were reported in 2002. Since then, Northern Spotted Owl populations have experienced substantial demographic changes, with potential attendant changes in natal dispersal distances, including temporal or geographic trends. We analyzed the natal dispersal of Northern Spotted Owls du
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Three-dimensional partitioning of resources by congeneric forest predators with recent sympatry

Coexistence of ecologically similar species can be maintained by partitioning along one or more niche axes. Three-dimensional structural complexity is central to facilitating resource partitioning between many forest species, but is underrepresented in field-based studies. We examined resource selection by sympatric northern spotted owls (Strix occidentalis caurina), a threatened species under the
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Barred owl research needs and prioritization in California

Barred owls (Strix varia) have reached high densities within the range of the northern spotted owl (S. occidentalis caurina) and are rapidly increasing in number within the range of the California spotted owl (S. o. occidentalis). Encroaching populations of barred owls pose a significant competitive threat to the viability of both spotted owl subspecies in California. In response, the Director of
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Ecosystems, Forest and Rangeland Ecosystem Science Center

Northern spotted owl habitat and populations: Status and threats

The northern spotted owl (Strix occidentalis caurina) was listed as threatened under the Endangered Species Act in 1990 (USFWS 1990). Providing adequate amounts of suitable forest cover to sustain the subspecies was a major component of the first recovery plan for northern spotted owls (USFWS 1992) and a driver in the basic reserve design and old-forest restoration under the Northwest Forest Plan
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Ecosystems, Forest and Rangeland Ecosystem Science Center

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

Populations of Northern Spotted Owls (Strix occidentalis caurina; hereinafter referred to as Spotted Owl) are declining throughout this subspecies’ geographic range. Evidence indicates that competition with invading populations of Barred Owls (S. varia) has contributed significantly to those declines. A pilot study in California showed that localized removal of Barred Owls coupled with conservatio
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Ecosystems, Wildlife Program, Forest and Rangeland Ecosystem Science Center

To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.

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Northern spotted owl

Northern Spotted Owl Still Fights for Survival

Three studies highlight how the interactions between northern spotted owl and the invasive barred owl are intertwined. 

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Ecosystems, Cooperative Research Units, Invasive Species Program, Wildlife Program, Forest and Rangeland Ecosystem Science Center, Northwest Climate Science Center, Southwest Biological Science Center, Communications and Publishing
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Invader Removal Halts Long-term Population Declines of Northern Spotted Owls

Invasive species can cause extinctions of native species and widespread biodiversity loss. Invader removal is a common management response, but the...

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Species Interactions Shape Increasing Rates of Breeding Dispersal of Northern Spotted Owls

Recent evidence suggests that frequency of breeding dispersal – the movement from one breeding territory to another – may be increasing in northern...

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Anticoagulant Rodenticides in Pacific Northwest Forest Owls

Researchers evaluated tissues from barred owls collected in Washington and Oregon to assess potential exposure of the Northern spotted owl and other...

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Effects of Barred Owl Removal on Population Demography of Northern Spotted Owls in Washington and Oregon, 2015–2018

A new USGS report summarizes research accomplishments and results from the first 3.5 years, 2015-2018, of a study in Oregon and Washington to...

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How Spotted and Barred Owls Share the Forest

Over the past century barred owls have been expanding their range westward, encroaching into the old-forest habitat of their sister species, the...

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Northwest Forest Plan Book Chapter: Northern Spotted Owl Habitat and Populations

Authors from the U.S. Forest Service and the USGS wrote a book chapter outlining how northern spotted owls shaped the Northwest Forest Plan.

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Geographic Variation in Natal Dispersal of Northern Spotted Owls over 28 Years

USGS and U.S. Forest Service researchers analyzed northern spotted owl natal dispersal, or the distance from natal site to first breeding site, from...

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Progress Report - Effects of Experimental Removal of Barred Owls on Population Demography of Northern Spotted Owls

Evidence suggests that the long-term persistence of northern spotted owls may be in question without additional management intervention.

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Golden Eagle Monitoring Plan for the Desert Renewable Energy Conservation Plan Area

This report outlines options for monitoring the status and population trends of golden eagles, a species specifically targeted for conservation under...

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Effects of Drought on Golden Eagles: Spatial Patterns in Occupancy and Reproduction

USGS scientists and collaborators investigated spatial patterns in occupancy and breeding success of golden eagles in the Altamont Pass Wind Resource...

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Science and Products