Date of Award:

5-2014

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Wildland Resources

Committee Chair(s)

David Koons

Committee

David Koons

Committee

Mevin Hooten

Committee

Peter Adler

Committee

Phaedra Budy

Committee

Frank Howe

Committee

James Powell

Abstract

Studying long-term ecological studies can help ecologists understand what causes populations and communities of wildlife to change. Understanding these causes can help guide conservation efforts. Additionally, results from long-term datasets allow ecologists to predict how populations may shift with global change. Ecologists can then determine necessary management action to maintain sustainable populations in the future. However, there can be a large amount of “noise” in a long-term dataset. If ecologists fail to account for this noise, they may make incorrect management decisions. For example, samples taken in two nearby locations will likely be more similar than samples taken from two distant locations. Closely related data points such as this can cause mistakes in the analysis that lead to flawed decisions. Fortunately, new statistical analyses for ecologists are able to make full use of the information present in long-term studies while properly accounting for these biases.

In this study, I use advanced statistical methods to analyze a long-term dataset, the Waterfowl Breeding Population and Habitat Survey. This aerial survey counts the number of ducks in upper North America each summer, and I will use it to answer questions about duck populations and communities. In Chapter 2, I estimate how the population of lesser and greater scaup (Aythya affinis and A. marila) has changed since 1955. These species are of interest because their population is thought to be declining. I conclude that the proportion of breeding scaup has remained the same, which means that some other portion of their migration cycle is the cause of the decline. In Chapter 3, I compare environmental effects on scaup in the Northwest Territories of Canada to see which might be the most important. My results indicate that the average annual snow cover, summer drought conditions, and density dependence have the most influence on the population in this location. Lastly, in Chapter 4 I include more species of ducks in my analysis to determine how they might be affected by changes in the environment. These results imply that the pochard community is affected the most by the environmental conditions in the NWT rather than interactions, such as competition, among members of the community.

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