Year of Award

2018

Document Type

Dissertation - Campus Access Only

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Wildlife Biology

Department or School/College

W.A. Franke College of Forestry and Conservation

Committee Chair

Victoria J. Dreitz

Commitee Members

Beth A. Hahn, Winsor H. Lowe, Paul M. Lukacs, Michael S. Mitchell

Keywords

Avian, Community, Disturbance, Richness, Sampling Design, Trend

Abstract

Monitoring programs are useful for assessing and informing conservation efforts but the methods used to gather monitoring data directly influence results. This presents a challenge when deciding on existing data to use to inform a given question. In Chapter 1, I illustrate the challenges of using monitoring data by comparing population trends from two avian monitoring programs: the Breeding Bird Survey and Integrated Monitoring in Bird Conservation Regions (IMBCR) programs. I use publicly available data from 2008–2015 for 148 species across Colorado, Montana, and Wyoming. Trends were inconsistent for 62% of the comparisons, and in 21 cases species trends increased and decreased at the same time. Chapter 1 results reflect the inherent differences between program design and analytical approach, and underscore the need to periodically revisit how I monitor natural resources. In Chapters 2 & 3, I use data from the IMBCR program and employ Bayesian multispecies occupancy models to assess responses of forest bird communities to disturbance. In Chapter 2, I study the effects of bark beetle-induced lodgepole pine (Pinus contorta) mortality on bird communities across four states: Colorado, Idaho, Montana, and Wyoming. Species richness varied little between sites with (N=19.35, 95%CRI=17.00, 22.01) and without outbreaks (N=20.23, 95%CRI=16.83, 24.25). Most species responding strongly to outbreaks (61%, N=17/28) belonged to two guilds: shrub and cavity nesting species. The presence of beetle outbreaks increased the occurrence of species that were otherwise less common potentially increasing bird richness over larger spatial scales. In Chapter 3, I test Huston’s Dynamic Equilibrium Model which predicts species richness to be maximized at intermediate levels of disturbance and ecosystem productivity. I measured species richness as a function of fire severity and productivity (GPP) across the mountain west. I found partial support for Huston’s model. The predicted relationship was present at lower latitudes but less apparent at higher latitudes. My results suggest, when productivity is regionally high, potentially reduced interspecific competition may be altering the expected relationship. However, my inferences are based on the spatial extent of my study and tests of Huston’s model at other scales may provide additional informative context for my findings.

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© Copyright 2018 William Michael Janousek