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- Behavioral plasticity; black bear; ecological trap; human development; human-caused mortality; population growth; population sink; space-use; survival; Ursus americanus. (1)
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Articles 1 - 20 of 20
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Changing Fire Regimes And Nuanced Impacts On A Critically Imperiled Species, Jeremy T. Rockweit, Katie M. Dugger, Damon B. Lesmeister, Raymond J. Davis, Alan B. Franklin, J. Mark Higley
Changing Fire Regimes And Nuanced Impacts On A Critically Imperiled Species, Jeremy T. Rockweit, Katie M. Dugger, Damon B. Lesmeister, Raymond J. Davis, Alan B. Franklin, J. Mark Higley
United States Department of Agriculture Wildlife Services: Staff Publications
Wildfire activity throughout western North America is increasing which can have important consequences for species persistence. Native species have evolved disturbance-adapted traits that confer resilience to natural disturbance provided disturbances operate within their historical range of variability. This resilience can erode as disturbance regimes change and begin operating outside this range. We assessed wildfire impacts during 1987–2018 on the northern spotted owl, an imperiled species with complex relationships with late and early seral forest in the Pacific Northwest, USA. We analyzed population- and individual-level wildfire impacts across the frequent-fire portion of the owl’s geographic range at two spatial scales and …
Tourism‑Supported Working Lands Sustain A Growing Jaguar Population In The Colombian Llanos, Matthew Hyde, Esteban Payán, Jorge Barragan, Diana Stasiukynas, Sanmantha Rincón, William L. Kendall, Jerónimo Rodríguez, Kevin R. Crooks, Stewart W. Breck, Valerie Boron
Tourism‑Supported Working Lands Sustain A Growing Jaguar Population In The Colombian Llanos, Matthew Hyde, Esteban Payán, Jorge Barragan, Diana Stasiukynas, Sanmantha Rincón, William L. Kendall, Jerónimo Rodríguez, Kevin R. Crooks, Stewart W. Breck, Valerie Boron
United States Department of Agriculture Wildlife Services: Staff Publications
Understanding large carnivore demography on human-dominated lands is a priority to inform conservation strategies, yet few studies examine long-term trends. Jaguars (Panthera onca) are one such species whose population trends and survival rates remain unknown across working lands. We integrated nine years of camera trap data and tourist photos to estimate jaguar density, survival, abundance, and probability of tourist sightings on a working ranch and tourism destination in Colombia. We found that abundance increased from five individuals in 2014 to 28 in 2022, and density increased from 1.88 ± 0.87 per 100 km2 in 2014 to 3.80 …
Estimating Northern Spotted Owl (Strix Occidentalis Caurina) Pair Detection Probabilities Based On Call-Back Surveys Associated With Long-Term Mark-Recapture Studies, 1993–2018, Katie M. Dugger, Alan B. Franklin, Damon B. Lesmeister, Raymond J. Davis, J. David Wiens, Gary C. White, James D. Nichols, James E. Hines, Charles B. Yackulic, Carl J. Schwarz, Steven A. Ackers, L. Steven Andrews, Larissa L. Bailey, Robin Bown, Jesse Burgher, Kenneth P. Burnham, Peter C. Carlson, Tara Chestnut, Mary M. Conner, Krista E. Dilione, Eric D. Forsman, Scott A. Gremel, Keith A. Hamm, Dale R. Herter, J. Mark Higley, Rob B. Horn, Julianna M. Jenkins, William L. Kendall, David W. Lapmphear, Christopher Mccafferty, Trent L. Mcdonald, Janice A. Reid, Jeremy T. Rockweit, David C. Simon, Stan G. Sovern, James K. Swingle, Heather Wise
Estimating Northern Spotted Owl (Strix Occidentalis Caurina) Pair Detection Probabilities Based On Call-Back Surveys Associated With Long-Term Mark-Recapture Studies, 1993–2018, Katie M. Dugger, Alan B. Franklin, Damon B. Lesmeister, Raymond J. Davis, J. David Wiens, Gary C. White, James D. Nichols, James E. Hines, Charles B. Yackulic, Carl J. Schwarz, Steven A. Ackers, L. Steven Andrews, Larissa L. Bailey, Robin Bown, Jesse Burgher, Kenneth P. Burnham, Peter C. Carlson, Tara Chestnut, Mary M. Conner, Krista E. Dilione, Eric D. Forsman, Scott A. Gremel, Keith A. Hamm, Dale R. Herter, J. Mark Higley, Rob B. Horn, Julianna M. Jenkins, William L. Kendall, David W. Lapmphear, Christopher Mccafferty, Trent L. Mcdonald, Janice A. Reid, Jeremy T. Rockweit, David C. Simon, Stan G. Sovern, James K. Swingle, Heather Wise
United States Department of Agriculture Wildlife Services: Staff Publications
The northern spotted owl (Strix occidentalis caurina; hereinafter NSO) was listed as “threatened” under the Endangered Species Act in 1990 and population declines have continued since that listing. Given the species’ protected status, any proposed activities on Federal lands that might impact NSO require consultation with U.S. Fish and Wildlife Service and part of that consultation often includes surveys to determine presence and occupancy status of the species in the proposed activity area. The objective of this report is to present study-area specific estimates of the probability of detection for NSO pairs from twelve 2-week seasonal survey periods …
An Efficient Method Of Evaluating Multiple Concurrent Management Actions On Invasive Populations, Amy J. Davis, Randy Farrar, Brad Jump, Parker Hall, Travis Guerrant, Kim M. Pepin
An Efficient Method Of Evaluating Multiple Concurrent Management Actions On Invasive Populations, Amy J. Davis, Randy Farrar, Brad Jump, Parker Hall, Travis Guerrant, Kim M. Pepin
United States Department of Agriculture Wildlife Services: Staff Publications
Evaluating the efficacy of management actions to control invasive species is crucial for maintaining funding and to provide feedback for the continual improvement of management efforts. However, it is often difficult to assess the efficacy of control methods due to limited resources for monitoring. Managers may view effort on monitoring as effort taken away from performing management actions. We developed a method to estimate invasive species abundance, evaluate management effectiveness, and evaluate population growth over time from a combination of removal activities (e.g., trapping, ground shooting) using only data collected during removal efforts (method of removal, date, location, number of …
Conserving Endangered Black-Footed Ferrets: Biological Threats, Political Challenges, And Lessons Learned, Travis M. Livieri, Steven C. Forrest, Marc R. Matchett, Stewart Breck
Conserving Endangered Black-Footed Ferrets: Biological Threats, Political Challenges, And Lessons Learned, Travis M. Livieri, Steven C. Forrest, Marc R. Matchett, Stewart Breck
United States Department of Agriculture Wildlife Services: Staff Publications
There may be few stories in the annals of wildlife management that are as dramatic as the near demise and comeback of the black-footed ferret (Mustela nigripes). Endemic only to North America, this charming little carnivore found only in the continent’s central grasslands was hardly known to science until the mid-20th century. By then, vast colonies of the prey it depended on for food and shelter, the prairie dog (Cynomys spp.), had been wiped out through disease (sylvatic plague) and an agricultural industry with little tolerance for burrowing and grazing rodents. At its low point, the species’ …
Range-Wide Declines Of Northern Spotted Owl Populations In The Pacific Northwest: A Meta-Analysis, Alan B. Franklin, Katie M. Dugger, Damon B. Lesmeister, Raymond J. Davis, J. David Wiens, Gary C. White, James D. Nichols, James E. Hines, Charles B. Yackulic, Carl J. Schwarz, Steven H. Ackers, L. Steven Andrews, Larissa L. Bailey, Robin Bown, Jesse Burgher, Kenneth P. Burnham, Peter C. Carlson, Tara Chestnut, Mary M. Conner, Krista E. Dilione, Eric D. Forsman, Elizabeth M. Glenn, Scott A. Gremel, Keith A. Hamm, Dale R. Herter, J. Mark Higley, Rob B. Horn, Julianna M. Jenkins, William L. Kendall, David W. Lamphear, Christopher Mccafferty, Trent L. Mcdonald, Janice A. Reid, Jeremy T. Rockweit, David C. Simon, Stan G. Sovern, James K. Swingle, Heather Wise
Range-Wide Declines Of Northern Spotted Owl Populations In The Pacific Northwest: A Meta-Analysis, Alan B. Franklin, Katie M. Dugger, Damon B. Lesmeister, Raymond J. Davis, J. David Wiens, Gary C. White, James D. Nichols, James E. Hines, Charles B. Yackulic, Carl J. Schwarz, Steven H. Ackers, L. Steven Andrews, Larissa L. Bailey, Robin Bown, Jesse Burgher, Kenneth P. Burnham, Peter C. Carlson, Tara Chestnut, Mary M. Conner, Krista E. Dilione, Eric D. Forsman, Elizabeth M. Glenn, Scott A. Gremel, Keith A. Hamm, Dale R. Herter, J. Mark Higley, Rob B. Horn, Julianna M. Jenkins, William L. Kendall, David W. Lamphear, Christopher Mccafferty, Trent L. Mcdonald, Janice A. Reid, Jeremy T. Rockweit, David C. Simon, Stan G. Sovern, James K. Swingle, Heather Wise
United States Department of Agriculture Wildlife Services: Staff Publications
The northern spotted owl (Strix occidentalis caurina) inhabits older coniferous forests in the Pacific Northwest and has been at the center of forest management issues in this region. The immediate threats to this federally listed species include habitat loss and competition with barred owls (Strix varia), which invaded from eastern North America. We conducted a prospective meta-analysis to assess population trends and factors affecting those trends in northern spotted owls using 26 years of survey and capture-recapture data from 11 study areas across the owls' geographic range to analyze demographic traits, rates of population change, and occupancy parameters for spotted …
Evaluating Potential Effects Of Solar Power Facilities On Wildlife From An Animal Behavior Perspective, Rachel Y. Chock, Barbara Clucas, Elizabeth K. Peterson, Bradley Blackwell, Daniel T. Blumstein, Kathleen Church, Esteban Fernández-Juricic, Gabriel Francescoli, Alison L. Greggor, Paul Kemp, Gabriela M. Pinho, Peter M. Sanzenbacher, Bruce A. Schulte, Pauline Toni
Evaluating Potential Effects Of Solar Power Facilities On Wildlife From An Animal Behavior Perspective, Rachel Y. Chock, Barbara Clucas, Elizabeth K. Peterson, Bradley Blackwell, Daniel T. Blumstein, Kathleen Church, Esteban Fernández-Juricic, Gabriel Francescoli, Alison L. Greggor, Paul Kemp, Gabriela M. Pinho, Peter M. Sanzenbacher, Bruce A. Schulte, Pauline Toni
United States Department of Agriculture Wildlife Services: Staff Publications
Solar power is a renewable energy source with great potential to help meet increasing global energy demands and reduce our reliance on fossil fuels. However, research is scarce on how solar facilities affect wildlife. With input from professionals in ecology, conservation, and energy, we conducted a research-prioritization process and identified key questions needed to better understand impacts of solar facilities on wildlife. We focused on animal behavior, which can be used to identify population responses before mortality or other fitness consequences are documented. Behavioral studies can also offer approaches to understand the mechanisms leading to negative interactions (e.g., collision, singeing, …
Individual And Population Fitness Consequences Associated With Large Carnivore Use Of Residential Development, Heather Johnson, David L. Lewis, Stewart W. Breck
Individual And Population Fitness Consequences Associated With Large Carnivore Use Of Residential Development, Heather Johnson, David L. Lewis, Stewart W. Breck
United States Department of Agriculture Wildlife Services: Staff Publications
Large carnivores are negotiating increasingly developed landscapes, but little is known about how such behavioral plasticity influences their demographic rates and population trends. Some investigators have suggested that the ability of carnivores to behaviorally adapt to human development will enable their persistence, and yet, others have suggested that such landscapes are likely to serve as population sinks or ecological traps. To understand how plasticity in black bear (Ursus americanus) use of residential development influences their population dynamics, we conducted a 6-yr study near Durango, Colorado, USA. Using space-use data on individual bears, we examined the influence of use of residential …
The Conundrum Of Agenda-Driven Science In Conservation, M. Zachariah Peery, Gavin M. Jones, R. J. Gutierrez, Steve M. Redpath, Alan B. Franklin, Daniel Simberloff, Monica G. Turner, Volker C. Radeloff, Gary C. White
The Conundrum Of Agenda-Driven Science In Conservation, M. Zachariah Peery, Gavin M. Jones, R. J. Gutierrez, Steve M. Redpath, Alan B. Franklin, Daniel Simberloff, Monica G. Turner, Volker C. Radeloff, Gary C. White
United States Department of Agriculture Wildlife Services: Staff Publications
Conservation biology is a value-laden discipline predicated on conserving biodiversity (Soulé 1985), a mission that does not always sit easily with objective science (Lackey 2007; Pielke 2007; Scott et al. 2007). While some encourage scientists to be responsible advocates for conservation (Garrard et al. 2016), others worry that objectivity in conservation research may suffer (Lackey 2007). At this time, we believe advocacy by scientists is essential for environmental conservation and, indeed, humanity. It is difficult to envision the state of our environment had scientists failed to encourage policy makers and the public to address emerging conservation problems. Nevertheless, conservation scientists …
Grass Is Not Always Greener: Rodenticide Exposure Of A Threatened Species Near Marijuana Growing Operations, Alan B. Franklin, Peter C. Carlson, Angela Rex, Jeremy T. Rockwelt, David Garza, Emily Culhane, Steven F. Volker, Robert J. Dusek, Valerie I. Shearn-Bochsler, Mourad W. Gabriel, Katherine E. Horak
Grass Is Not Always Greener: Rodenticide Exposure Of A Threatened Species Near Marijuana Growing Operations, Alan B. Franklin, Peter C. Carlson, Angela Rex, Jeremy T. Rockwelt, David Garza, Emily Culhane, Steven F. Volker, Robert J. Dusek, Valerie I. Shearn-Bochsler, Mourad W. Gabriel, Katherine E. Horak
United States Department of Agriculture Wildlife Services: Staff Publications
Marijuana (Cannabis spp.) growing operations (MGO) in California have increased substantially since the mid-1990s. One environmental side-effect of MGOs is the extensive use of anticoagulant rodenticides (AR) to prevent damage to marijuana plants caused by wild rodents. In association with a long-term demographic study, we report on an observation of brodifacoum AR exposure in a threatened species, the northern spotted owl (Strix occidentalis caurina), found freshly dead within 669–1347 m of at least seven active MGOs.
An Evaluation Of The Use Of Pentosidine As A Biomarker For Ageing Turtles, John B. Iverson, Randal S. Stahl, Carol Furcolow, Fred Kraus
An Evaluation Of The Use Of Pentosidine As A Biomarker For Ageing Turtles, John B. Iverson, Randal S. Stahl, Carol Furcolow, Fred Kraus
United States Department of Agriculture Wildlife Services: Staff Publications
Concentrations of the biomarker pentosidine have been shown to be useful measures of age for a number of avian and mammalian species. However, no study has examined its usefulness as an age marker in a long-lived ectotherm despite the fact that such a marker could prove useful in understanding age distributions of populations subject to conservation programmes. Therefore, we evaluated pentosidine concentrations in the interdigital webbing of 117 female yellow mud turtles (Kinosternon flavescens) at a 35 year study site in western Nebraska where nearly all turtles are of known age. Pentosidine concentrations were extraordinarily low and positively …
Differential Impacts Of Wildfire On The Population Dynamics Of An Old-Forest Species, Jeremy T. Rockweit, Alan B. Franklin, Peter C. Carlson
Differential Impacts Of Wildfire On The Population Dynamics Of An Old-Forest Species, Jeremy T. Rockweit, Alan B. Franklin, Peter C. Carlson
United States Department of Agriculture Wildlife Services: Staff Publications
Ecological disturbances shape and maintain natural communities, but climate change and human land use can alter disturbance regimes and affect population persistence and vital rates in unpredictable ways. Species inhabiting landscapes shaped by wildfire have evolved mechanisms allowing them to persist under this dynamic disturbance type, which creates habitats of varying quality for these species. We utilized data from a 26-yr demographic study of northern spotted owls to analyze the influence of wildfire on apparent survival and recruitment rates. Wildfires occurred across different years and affected different spotted owl territories, which allowed us to implement a retrospective Before-After-Control-Impact (BACI) analysis …
Quantile Regression Of Microgeographic Variation In Population Characteristics Of An Invasive Vertebrate Predator, Shane R. Siers, Julie A. Savidge, Robert N. Reed
Quantile Regression Of Microgeographic Variation In Population Characteristics Of An Invasive Vertebrate Predator, Shane R. Siers, Julie A. Savidge, Robert N. Reed
United States Department of Agriculture Wildlife Services: Staff Publications
Localized ecological conditions have the potential to induce variation in population characteristics such as size distributions and body conditions. The ability to generalize the influence of ecological characteristics on such population traits may be particularly meaningful when those traits influence prospects for successful management interventions. To characterize variability in invasive Brown Treesnake population attributes within and among habitat types, we conducted systematic and seasonally-balanced surveys, collecting 100 snakes from each of 18 sites: three replicates within each of six major habitat types comprising 95% of Guam's geographic expanse. Our study constitutes one of the most comprehensive and controlled samplings of …
Bayesian Model-Based Age Classification Using Small Mammal Body Mass And Capture Dates, Nathaneal Lichti, Kenneth F. Kellner, Timothy J. Smyser, Scott A. Johnson
Bayesian Model-Based Age Classification Using Small Mammal Body Mass And Capture Dates, Nathaneal Lichti, Kenneth F. Kellner, Timothy J. Smyser, Scott A. Johnson
United States Department of Agriculture Wildlife Services: Staff Publications
Accurate age determination is a fundamental prerequisite for demographic studies as well as population monitoring efforts that provide information for management and conservation. Yet, common age determination methods suffer from low accuracy rates, impose additional handling and time costs on animals and biologists, or rely on invasive techniques such as tooth extraction. We introduce an alternative, mixture modeling approach for age determination that exploits mammalian growth patterns to classify newly encountered animals as juveniles or adults, and present an example analysis that classifies Allegheny woodrats based solely on their capture dates and mass at capture, in combination with data from …
The Effects Of Habitat, Climate, And Barred Owls On Long-Term Demography Of Northern Spotted Owls, Katie M. Dugger, Eric D. Forsman, Alan B. Franklin, Raymond J. Davis, Gary C. White, Carl J. Schwarz, Kenneth P. Burnham, James D. Nichols, James E. Hines, Charles B. Yackulic, Paul F. Doherty Jr., Larissa Bailey, Darren A. Clark, Steven H. Ackers, Lawrence S. Andrews, Benjamin Augustine, Brian L. Biswell, Jennifer Blakesley, Peter C. Carlson, Matthew J. Clement, Lowell V. Diller, Elizabeth M. Glenn, Adam Green, Scott A. Gremel, Dale R. Herter, J. Mark Higley, Jeremy Hobson, Rob B. Horn, Kathryn P. Huyvaert, Christopher Mccafferty, Trent Mcdonald, Kevin Mcdonnell, Gail S. Olson, Janice A. Reid, Jeremy Rockweit, Viviana Ruiz, Jessica Saenz, Stan G. Sovern
The Effects Of Habitat, Climate, And Barred Owls On Long-Term Demography Of Northern Spotted Owls, Katie M. Dugger, Eric D. Forsman, Alan B. Franklin, Raymond J. Davis, Gary C. White, Carl J. Schwarz, Kenneth P. Burnham, James D. Nichols, James E. Hines, Charles B. Yackulic, Paul F. Doherty Jr., Larissa Bailey, Darren A. Clark, Steven H. Ackers, Lawrence S. Andrews, Benjamin Augustine, Brian L. Biswell, Jennifer Blakesley, Peter C. Carlson, Matthew J. Clement, Lowell V. Diller, Elizabeth M. Glenn, Adam Green, Scott A. Gremel, Dale R. Herter, J. Mark Higley, Jeremy Hobson, Rob B. Horn, Kathryn P. Huyvaert, Christopher Mccafferty, Trent Mcdonald, Kevin Mcdonnell, Gail S. Olson, Janice A. Reid, Jeremy Rockweit, Viviana Ruiz, Jessica Saenz, Stan G. Sovern
United States Department of Agriculture Wildlife Services: Staff Publications
Estimates of species’ vital rates and an understanding of the factors affecting those parameters over time and space can provide crucial information for management and conservation. We used mark–recapture, reproductive output, and territory occupancy data collected during 1985–2013 to evaluate population processes of Northern Spotted Owls (Strix occidentalis caurina) in 11 study areas in Washington, Oregon, and northern California, USA. We estimated apparent survival, fecundity, recruitment, rate of population change, and local extinction and colonization rates, and investigated relationships between these parameters and the amount of suitable habitat, local and regional variation in meteorological conditions, and competition with …
Ecosystem Services Provided By Avian Scavengers, Travis L. Devault, James C. Beasley, Zachary H. Olson, Marcos Moleón, Martina Carrete, Antoni Margalida, José Antonio Sánchez-Zapata
Ecosystem Services Provided By Avian Scavengers, Travis L. Devault, James C. Beasley, Zachary H. Olson, Marcos Moleón, Martina Carrete, Antoni Margalida, José Antonio Sánchez-Zapata
United States Department of Agriculture Wildlife Services: Staff Publications
Food webs developed under classical theoretical models often depict simplistic interactions among trophic levels linked by predation (Hairston et al. 1960). As a result, extensive research efforts have been devoted to studying predator-prey interactions, often ignoring the contribution of scavenging in food-web dynamics. However, recent advancements in food-web theory have recognized the widespread and critical role that scavenging plays in stabilizing food webs in ecosystems throughout the world, thus suggesting that previous models may have greatly underestimated the importance of scavenging in food web research ( Wilson and Wolkovich 2011; Barton et al. 2013). Such disregard for the importance of …
Is Anthropogenic Cougar Mortality Compensated By Changes In Natural Mortality In Utah? Insight From Long-Term Studies, Michael L. Wolfe, David N. Koons, David C. Stoner, Patricia Terletzky, Eric M. Gese, David M. Choate, Lise M. Aubry
Is Anthropogenic Cougar Mortality Compensated By Changes In Natural Mortality In Utah? Insight From Long-Term Studies, Michael L. Wolfe, David N. Koons, David C. Stoner, Patricia Terletzky, Eric M. Gese, David M. Choate, Lise M. Aubry
United States Department of Agriculture Wildlife Services: Staff Publications
Understanding the interplay between exploitation and natural mortality is essential to guiding sustainable conservation of wildlife. Exploitation of carnivores by humans has long been thought to result in compensatory reductions of natural mortality among survivors. If rates of human exploitation exceed natural mortality, however, such actions will ‘add’ to overall mortality and could imperil the sustainability of such actions. We applied competing risk analyses to >/= 16 years of data for heavily harvested and semi-protected cougar populations in Utah to test the additive and compensatory mortality hypotheses, while accounting for parameter uncertainty. We additionally tested for presence of the two …
Is Anthropogenic Cougar Mortality Compensated By Changes In Natural Mortality In Utah? Insight From Long-Term Studies, Michael L. Wolfe, David N. Koons, David C. Stoner, Patricia Terletzky, Eric M. Gese, David M. Choate, Lise M. Aubry
Is Anthropogenic Cougar Mortality Compensated By Changes In Natural Mortality In Utah? Insight From Long-Term Studies, Michael L. Wolfe, David N. Koons, David C. Stoner, Patricia Terletzky, Eric M. Gese, David M. Choate, Lise M. Aubry
United States Department of Agriculture Wildlife Services: Staff Publications
Understanding the interplay between exploitation and natural mortality is essential to guiding sustainable conservation of wildlife. Exploitation of carnivores by humans has long been thought to result in compensatory reductions of natural mortality among survivors. If rates of human exploitation exceed natural mortality, however, such actions will ‘add’ to overall mortality and could imperil the sustainability of such actions. We applied competing risk analyses to >16 years of data for heavily harvested and semi-protected cougar populations in Utah to test the additive and compensatory mortality hypotheses, while accounting for parameter uncertainty. We additionally tested for presence of the two primary …
Potential Influences Of Climate And Nest Structure On Spotted Owl Reproductive Success: A Biophysical Approach, Jeremy T. Rockweit, Alan B. Franklin, George S. Bakken, R. J. Gutierrez
Potential Influences Of Climate And Nest Structure On Spotted Owl Reproductive Success: A Biophysical Approach, Jeremy T. Rockweit, Alan B. Franklin, George S. Bakken, R. J. Gutierrez
United States Department of Agriculture Wildlife Services: Staff Publications
Many bird species do not make their own nests; therefore, selection of existing sites that provide adequate microclimates is critical. This is particularly true for owls in north temperate climates that often nest early in the year when inclement weather is common. Spotted owls use three main types of nest structures, each of which are structurally distinct and may provide varying levels of protection to the eggs or young. We tested the hypothesis that spotted owl nest configuration influences nest microclimate using both experimental and observational data. We used a wind tunnel to estimate the convective heat transfer coefficient ( …
Who Hits And Hoots At Whom? Potential For Interference Competition Between Barred And Northern Spotted Owls, Nicholas J. Van Lanen, Alan B. Franklin, Kathryn P. Huyvaert, Raoul F. Reiser Ii, Peter C. Carlson
Who Hits And Hoots At Whom? Potential For Interference Competition Between Barred And Northern Spotted Owls, Nicholas J. Van Lanen, Alan B. Franklin, Kathryn P. Huyvaert, Raoul F. Reiser Ii, Peter C. Carlson
United States Department of Agriculture Wildlife Services: Staff Publications
The northern spotted owl (Strix occidentalis caurina) is a controversial species in the Pacific Northwest that is listed as threatened under the Endangered Species Act. The barred owl (Strix varia), a species historically restricted to eastern North America, has recently expanded its range to completely overlap that of the northern spotted owl. Recent evidence suggests that barred owls may compete with northern spotted owls and may be one cause for recent declines in some northern spotted owl populations. Our focus was to examine whether barred owls have the potential to competitively exclude northern spotted owls from …