Current Research
My research focuses on using/developing quantitative tools to learn about population and community level processes in vertebrates, with the goal of informing conservation actions. While my current research is on bird population dynamics, I have conducted research on reptiles, amphibians, fish and mammals too.
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The focal species of my current research is the tricolored blackbird. Tricolored blackbirds are almost entirely found in California, with a small percentage (~1-5%) breeding in Nevada, Washington and Oregon. Their populations have declined precipitously over the last 80 years. The goal of my project is to understand their habitat associations, movement, and demographic rates throughout the annual cycle. While these are common topics in many bird studies, the nature of the available data and lack of knowledge about many aspects of the tricolored blackbird's annual cycle make even this basic information difficult to characterize.
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Modeling rare species’ distributions is a pressing challenge for conservation and applied research. Often, a large number of surveys are required before enough detections occur to model distributions of rare species accurately, resulting in a data set with a high proportion of non-detections (i.e. class imbalance). Citizen science data can provide a cost-effective source of surveys, but likely suffer from class imbalance. Citizen science data also suffer from spatial bias, likely from preferential sampling. In order to correct for class imbalance and spatial bias, we used spatial filtering to under-sample the majority class (non-detection) while maintaining all of the limited information from the minority class (detection). We compared this method with several others and found that our spatial under-sampling method was the most accurate for species distribution models. We then used this method to create winter and breeding season distribution maps for tricolored blackbirds.
Conservation
Community Ecology
Population Ecology
It is imperative to understand population processes of species of concern if we are to effectively conserve them. Often it is possible to study a population in the field to gain a better understanding of the processes driving the trajectory of its growth or decline. Many times it is not possible to conduct field studies on certain aspects of a species' life history for one reason or another. In these cases simulation models are useful to gain insight into population dynamics. I have used data from field studies and simulation models, to explore population-level processes.
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Populations do not exist in a vacuum; that is, multiple species may be affected by the decline or increase in another, as many species interact. While it is important that we understand population-level processes, knowledge of species interactions can be just as important for conservation. As with my population studies, I have used both simulation modeling approaches and field based studies to examine community dynamics and how conservation efforts may be guided by them.
Most of my projects are focused on some aspect of population or community ecology, with conservation being a consistent theme among them. For others, an aspect of conservation is the main focus of the project. To this end, I have added to the quantitative framework by which potential management actions are evaluated and have conducted species-specific conservation studies.
Predicted distribution maps for tricolored blackbirds in the breeding season (left panel) and winter (right panel). The colors represent the probability of occurrence for a tricolored blackbird at a given pixel. Pixels with warmer colors have a higher probability of being occupied by a tricolored blackbird. Note the different scale for each panel.