Many statistical approaches have been used for developing predictive models for wildlife presence/absence and abundance, each with varying levels of accuracy and complexity. As concerns for declining species intensify and anthropogenic impacts on habitats increase, the ability to quickly quantify and map species distributions and abundances over large regions will become increasingly important. To date, there is no set of best practices for modeling specific wildlife groups. My primary objectives with this thesis were to 1) compare model techniques for ease of use and accuracy, and 2) compare resolution of species occurrence data and its effect on model accuracy. For the first objective, I compared two modeling techniques that range from moderately quick and simplistic (decision trees) to conceptually and computationally complex (hierarchical spatial models). I used North American Breeding Bird Survey counts with a suite of explanatory variables to predict presence and abundance of cerulean warblers (Dendroica cerulea) in the Appalachian Mountains Bird Conservation Region. Of the decision tree methods, cerulean warbler occurrence was most accurately described by presence/absence models. Regression tree abundance models under-predicted counts and had low accuracy. Hierarchical spatial models predicted abundance of cerulean warblers similar to actual counts, and with better overall accuracy than regression trees. All techniques produced models using similar variables; interior forest and percent forest were most important for identifying areas with cerulean warblers. For the second objective, I compared two model types, differing in the resolution of the species distribution data. I used North American Breeding Bird Survey (NABBS) counts with a suite of explanatory variables to predict presence and abundance of cerulean warblers (Dendroica cerulea) in the Appalachian Mountains Bird Conservation Region (BCR28). Decision trees were created for route-level and stop-level analyses of presence and abundance. Additionally, output maps have typically been resolved to the resolution of the environmental spatial datasets with little attention given to the scale at which the predictions represent. Using the modeling results, predictive distribution maps were created for cerulean warblers with appropriate resolutions for each model group. Route-level decision trees performed better than stop-level models for predicting both presence and abundance of cerulean warblers. Similar to raw NABBS distribution data, cerulean warblers were predicted to occur in highest concentrations in the central portions of the BCR. Poor performance of stop-level models may result from a mismatch of resolution of environmental data to species survey data, or lack of important environmental covariates at the stop-level scale. The results of this study highlight the importance of correctly matching the resolution of the species distribution data to the resolution of environmental covariates and the extent of analysis. The results and relationships hig...
Birds that inhabit open lands such as grasslands and shrublands are rapidly declining across North America. A common practice for multi-species management is to focus on umbrella species whose habitat requirements overlap with several other species.We evaluated whether the northern bobwhite (Colinus virginianus; bobwhite) could serve as an umbrella species for openland birds in Ohio, USA. We related landscape metrics to abundance patterns and assessed whether bobwhite occupancy positively predicts presence of open-land birds. We combined bird survey data from the second Ohio Breeding Bird Atlas (2006-2011) with land cover data from the 2011 National Land Cover Database (Homer et al. 2015) to construct single-season N-mixture models to identify landscape metrics that influence bobwhite abundance. Bobwhite abundance was positively predicted by forest cohesion, percent agriculture, percent barren, and percent grassland. Of the 34 focal species, bobwhites were a significant positive predictor for 12, and a significant negative predictor for 10. The model with only bobwhite occupancy probability as a predictor was the best supported model for only willow flycatcher (Empidonax traillii).These results suggest that bobwhite land cover type requirements are too specialized to meet the needs of broader species guilds, instead affording protection for a narrower range of individual species that share specific habitat requirements with bobwhites. Management for bobwhites may still be able to promote co-occurrence for declining species across multiple guilds by identifying locations where focused management can
The central Appalachian landscape is being heavily altered by surface coal mining. The practice of Mountaintop Removal/Valley Fill (MTRVF) mining has transformed large areas of mature forest to non-forest and created much forest edge, affecting habitat quality for mature forest wildlife. The Appalachian Regional Reforestation Initiative is working to restore mined areas to native hardwood forest conditions, and strategies are needed to prioritize restoration efforts for wildlife. We present mineland reforestation guidelines for the imperiled Cerulean Warbler, considered a useful umbrella species, in its breeding range. In 2009, we surveyed forest predicted to have Cerulean Warblers near mined areas in the MTRVF region of West Virginia and Kentucky. We visited 36 transect routes and completed songbird surveys on 151 points along these routes. Cerulean Warblers were present at points with fewer large-scale canopy disturbances and more mature oak-hickory forest. We tested the accuracy of a predictive map for this species and demonstrated that it can be useful to guide reforestation efforts. We then developed a map of hot spot locations that can be used to determine potential habitat suitability. Restoration efforts would have greatest benefit for Cerulean Warblers and other mature forest birds if concentrated near a relativeabundance hot spot, on north-and east-facing ridgetops surrounded by mature deciduous forest, and prioritized to reduce edges and connect isolated forest patches. Our multi-scale approach for prioritizing restoration efforts using an umbrella species may be applied to restore habitat impacted by a variety of landscape disturbances.
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