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Date of Award

Spring 2026

Rights

Access restricted for 2 years to EWU users with an active EWU NetID

Date Available to Non-EWU Users

2028-06-01

Document Type

Thesis: EWU Only

Degree Name

Master of Science (MS) in Biology

Department

Biology

First Advisor

Dr. Charlotte Milling

Second Advisor

Dr. Justin Bastow

Third Advisor

Dr. Ashley Lamm

Abstract

Nest predation is a primary factor influencing waterfowl productivity in the Prairie Pothole Region (PPR) of North America. Although this system is intensely managed and studied, research has largely focused on how predators affect waterfowl populations, with comparatively little attention to how predators actually rely on waterfowl as a resource. Understanding predator feeding ecology is therefore critical for informing effective management strategies and interpreting the complexity of predator-prey interactions on this landscape. My objective overall was to elucidate the feeding ecology of nine focal predator species commonly associated with waterfowl nest predation in the Aspen Parkland Ecoregion of the PPR: Coyotes (Canis latrans), red foxes (Vulpes vulpes), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), American badgers (Taxidea taxus), Franklin’s ground squirrels (Poliocitellus franklinii), American crows (Corvus brachyrhynchos), common ravens (Corvus corax), and black-billed magpies (Pica hudsonia). Using stable isotope analysis, I specifically aimed to investigate 1) waterfowl egg contribution to diet relative to other putative prey sources for each predator species; 2) diet composition differences considering demographic classes (i.e., sex and age); 3) predator position along a generalist to specialist foraging spectrum; 4) and intraspecific diet variation over time. Results revealed substantial variability in dietary breadth among species (coyotes [SEAB = 0.98 ‰2] to raccoons [SEAB = 8.98 ‰2]) and among individual raccoons (raccoon #13 [SEAB = 0.10 ‰2] to raccoon #3 [SEAB = 8.08 ‰2]). Waterfowl egg contribution varied between species, with American badgers exhibiting the highest egg contribution to diet (0.595 ± 0.045) and common ravens exhibiting the lowest egg contribution to diet (0.034 ± 0.026). Waterfowl egg contribution to diet among raccoon individuals also varied substantially, from over 90% of assimilated diet (raccoon #11 [0.909 ± 0.46]) to nearly 0% of assimilated diet (raccoon #3 [0.004 ± 0.06]). Analyzing diet over the waterfowl nesting season within raccoon individuals revealed increases in waterfowl egg contribution to diet corresponding to waterfowl egg availability and ecological conditions. This work challenges traditional assumptions about which predators may be important for management purposes. By explicitly considering predator reliance on waterfowl alongside their broader diets, from species to individual, this research provides critical insights into predator-prey interactions and the development of informed conservation strategies aimed at supporting waterfowl nesting success in the PPR.

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