Postdoctoral Fellow Wildlife Researcher

The Colorado Cooperative Fish and Wildlife Research Unit enhances graduate education in fisheries and wildlife sciences, and facilitates research among cooperators and partners including Colorado Parks and Wildlife, the U. S. Geological Survey, the U. S. Fish and Wildlife Service, and the Wildlife Management Institute. Research conducted by the Unit involves graduate and post-doctoral education and technical assistance to our Cooperators to understand and manage fish and wildlife resources in Colorado and elsewhere. General areas of emphasis include aquatic ecology and fish biology, population and community monitoring and modeling, the analysis of animal movement and spatio-temporal ecological processes, and disease ecology and epidemiology.

Recently, gray wolves (Canis lupus) are beginning to recover in northern Colorado through natural recolonization and voter-mandated reintroduction led by Colorado Parks and Wildlife (CPW). The recovery of wolves may alter Colorado’s ecological communities in several ways. Wolf impacts on prey populations can be both direct (i.e., predation) and indirect (i.e., behavioral responses). If these prey impacts are great enough, changes in plant communities may follow. In addition to herbivore pressure, plant communities are impacted by many factors such as changing precipitation patterns, drought, disease, management history, and wildfire. How these factors impact winter browse species is especially important for elk and mule deer survival. These dynamics play out on the scale of decades, requiring long-term research to understand how these factors influence plant communities.

Our goal is to design an observational research study aimed at untangling the impacts of wolves and mountain lions on aspen and mountain shrub growth and recruitment; mechanistically, this would occur via changes in elk and mule deer browsing pressures in response to predators. More specifically, we aim to measure plant growth, browsing pressure, and recruitment on a variety of important winter forage species while controlling for abiotic, anthropogenic, and historical factors (e.g., slope, soil moisture, hunting pressure, management, fire history), and examining the influence of predator-related factors (e.g., wolf and mountain lion risk). This project will support a postdoctoral researcher to help in study design development in two phases.

Phase 1: Sample size determination and site selection Sample size determination and site selection are the most critical components of study design and must occur prior to formal sampling. This will require model simulations that capture the complexity of the study system. Briefly, probable data sets will need to be generated for all variables of interest. This will require a literature review and potentially ground-truthing in Colorado. Then, simulations will be performed in order to identify the number of samples necessary to detect effects of predators, if they occur, under various scenarios (e.g., browsing pressure and timing, environmental variation, number of sample sites, and predator effects on browsers). Additionally, this exercise will help identify constraints on site selection and possible tradeoffs on variables that can and cannot be controlled for. At the end of this phase, we should have geospatial boundaries around areas of land in Colorado where a determined number of sites could be randomly selected across important strata (e.g., wildfire recency).

Phase 2: Site validation and manuscript preparation We know that geospatial land cover data may not accurately represent a site. Therefore, site locations will be proposed (under the constraints determined in Phase 1), and must be validated. This will involve visiting sites to ensure they meet study criteria. The postdoctoral researcher may perform some of the site visits, or otherwise help advise CPW staff in performing site visits. The final products of this project will be 1) a scientific manuscript submitted for peer-review and publication, and 2) geospatial information on potential long-term study sites in Colorado. The goal of this manuscript is to provide a guide to ecologists for best practices in designing long-term observational studies to study community effects from changing predator populations. This research study will be used as a case study in the manuscript.