Year of Award

2018

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Wildlife Biology

Department or School/College

W.A. Franke College of Forestry and Conservation

Committee Chair

Thomas E. Martin

Commitee Members

Kate R. Stone, Mark Hebblewhite, Bret W. Tobalske

Keywords

nest success, lewis's woodpecker, burned forest, cottonwood floodplain forest, abundance estimates, habitat selection

Subject Categories

Ornithology | Other Ecology and Evolutionary Biology | Population Biology

Abstract

Breeding habitat selection influences reproductive outcomes. Habitat selection may be adaptive and benefit populations, but it can also be maladaptive with negative consequences for populations. Understanding habitat selection and its influence on reproductive success, especially in species of concern, is critical for effective management. Lewis’s Woodpecker (Melanerpes lewis) is a Species of Concern that has experienced national population declines. We studied its abundance and reproductive success in two commonly selected breeding forest types (i.e., cottonwood floodplain and mixed-conifer burned), and nest-site characteristics (nest availability, food availability, and vegetation attributes) that have the potential to yield strong differences in abundance and reproductive success. We analyzed abundance estimates from valley-wide surveys, and computed nest success from 217 nests monitored in floodplain and burned forest. We found densities 2.5 to 5.5 times higher in floodplain than in burned forest, despite lower nest success in floodplain (73%) versus burned forest (86%). We found that Lewis’s chose to nest in tall trees, areas with low canopy cover, and in mature tree stands. Insect abundance did not explain differences in attrition or nest success across forest types, but phenology of insect availability and suitable tree density for nesting correlated with differences in abundances. Our research suggests management strategies aimed at conserving Lewis’s Woodpecker habitat need to focus on the retention of large diameter snags in both floodplain forest and mixed-conifer burned forest, as well as protecting recruitment of cottonwoods in the floodplain.

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© Copyright 2018 William M. Blake