Date of Award:
Doctor of Philosophy (PhD)
Studying long-term ecological studies allows for a better understanding of processes driving populations and communities, and this understanding can be used to improve conservation eorts. These studies can describe how changes in the environment have led to current states of populations and communities, and indicate if the current state or trend falls within expectations based on past dynamics. Studies of long-term datasets also help ecologists predict how populations may shift with climate, water, or land-use change and determine necessary management action to maintain sustainable populations and community interactions. Serving as a \test of time," long-term monitoring can provide insight into the in uence of predation, intra- or interspecic competition, and other interactions on system dynamics. Studies need to explicitly include these drivers and sources of autocorrelation in data (e.g., spatial autocorrelation) to obtain unbiased estimates of ecological processes for guiding management. Fortunately, new statistical analyses for ecological applications are available that help ecologists make full use of the information present in long-term studies while properly accounting for sampling error and autocorrelation. In this study, I use advanced statistical methods to analyze a long-term dataset, the Waterfowl Breeding Population and Habitat Survey, and address questions about waterfowl population and community dynamics. In Chapter 2, I use multi-state occupancy models to determine how the presence of lesser and greater scaup (Aythya anis and A. marila) has changed on their breeding grounds in North America since 1955. In Chapter 3, I use a Bayesian hierarchical model to determine the drivers of the breeding scaup population in the Northwest Territories of Canada. Lastly, in Chapter 4 I incorporate more waterfowl species into the hierarchical model from Chapter 3 to determine the drivers of the pochard duck community, along with the role of species interactions. My results indicate that the occupancy of scaup has decreased in the boreal forest of Canada and increased in the prairie parklands. Additionally, scaup in the Northwest Territories are largely in uenced by density dependence and snow cover extent. Finally, the pochard community in the Northwest Territories is regulated more by environmental drivers than intra- or interspecic interactions. These results indicate that management of the species through hunting regulations likely deserves further study, as scaup likely exhibit some sort of compensation in response to hunting.
Ross, Beth E., "Assessing Changes in Waterfowl Population and Community Dynamics" (2014). All Graduate Theses and Dissertations. 2174.
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