Date of Award

January 2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Susan N. Felege

Abstract

Reproductive decisions of birds are shaped by minimizing predation while meeting physiological needs of parents and offspring. As a result, birds must make decisions about investment in offspring that allows them to maximize their overall fitness. This often drives nesting behaviors and can provide insights into reproductive success. Common eiders (Somateria mollissima) are thought to have high nest attendance (time spent tending the nest) and use substantial energetic resources during breeding. However, the specific behaviors at the nest of these birds are not well studied, with even less known about the Hudson Bay common eider (S. m. sedentaria). The objectives of this study were to determine (1) if colony characteristics and nest age influence nest attendance patterns, (2) if these patterns influence the probability of predation from a specific predator, and (3) what invertebrate resources are available to eiders and what factors impact the availability of those resources. To address our first and second objectives we used data collected during the summers of 2014 to 2017 where we captured nest attendance patterns and their fates at 103 common eider nests using time-lapse imagery from trail cameras. We found eiders spend 95.65% of a day on the nest on average, take 1.4 recesses per day and are gone on recess for an average duration of 43.51 minutes. We did not find nest age or colony characteristics to be major drivers in attendance patterns. Common eider nest predators included arctic foxes (Vulpes lagopus), red foxes (Vulpes vulpes), grizzly bears (Ursus arctos), polar bears (Ursus maritimus), sandhill cranes (Antigone canadensis), herring gulls (Larus argentatus), and bald eagles

(Haliaeetus leucocephalus). Annual variation was the most important factor driving nest success. When exploring what predator would consume a nest, we found the best predictor was timing within the breeding season. For our third objective, we collected aquatic invertebrates in June and July of 2016 and 2017 and compared our findings to data collected in 2003 and 2004. We created models and used AIC model selection to determine the factors that most simply and best explained abundance of individuals in each invertebrate. We found flow, season, substrate type and sediment depth appeared in most of our models. When comparing our findings to the initial collections in 2003 and 2004, we found increased sedimentation across our sampling sites. Finally, we used ANOVAs and discriminate analyses to investigate if stable isotope values of 13C and 15N collected from aquatic invertebrates were different among the four different water types they were collect in (Mast River freshwater, Wawao Creek freshwater, brackish, and marine). We found that no difference in 13C samples between our two freshwater sources, but did find variation in our 15N samples which are likely different from the proportions of different types of invertebrate categories collected. Our brackish samples to not be different from freshwater sources but did find marine samples to be unique from all other samples. Findings from this study provide important natural history information on the nesting ecology of the common eider and provide a foundation for future research exploring availability of invertebrate resources for breeding birds in the area.

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