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2017

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Articles 121 - 123 of 123

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Differential Impacts Of Wildfire On The Population Dynamics Of An Old-Forest Species, Jeremy T. Rockweit, Alan B. Franklin, Peter C. Carlson Jan 2017

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 Jan 2017

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 Jan 2017

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 …