Year of Award

2013

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Environmental Studies

Department or School/College

Environmental Studies Program

Committee Chair

Len Broberg

Commitee Members

Richard Hutto, Anna Noson

Keywords

cottonwood, habitat, Lewis's Woodpeckers, management, Melanerpes lewis, nest phenology, nest success, use vs. availability

Abstract

The Lewis’s Woodpecker (Melanerpes lewis) is known to breed in ponderosa pine, cottonwood riparian, aspen, and burned conifer forest types, but is declining in much of its range throughout the U.S. and is listed as a Level II Species of Concern in Montana. In western Montana, Lewis’s Woodpeckers commonly breed in riparian bottomlands, but information on characteristics of their preferred nesting habitat within these areas is lacking. I studied nesting habitat use by Lewis’s Woodpeckers in two important breeding areas in cottonwood-dominated riparian forest along the Clark Fork and Bitterroot rivers in western Montana. I found 55 nests during the summer of 2012, and measured vegetation characteristics around 38 of those nest sites as well as 30 randomly located sites within the same forests. My main objective was to examine nest-tree, local, and landscape habitat characteristics of Lewis’s Woodpeckers at nest sites and random sites to determine whether sites used in western Montana river systems were a nonrandom subset of bottomland conditions and whether used conditions were similar to those reported from other parts of their geographic range. Logistic regression models were developed based on used sites and available sites within the study area. Results showed that Lewis’s Woodpeckers used larger snags in areas with relatively high percent shrub cover and relatively high snag density per hectare. Snags provide perches to forage from, cavities for nesting, and an open canopy, while the shrub understory supports arthropod prey. From a landscape perspective, Lewis’s Woodpeckers nest sites were closer to agricultural fields than were randomly located sites, suggesting adjacent fields were preferred. Information from this study will be disseminated to land managers and private landowners, recommending desired vegetation conditions to benefit this species, including snag retention. To ensure that conditions suitable for Lewis’s Woodpecker are maintained in perpetuity will also require management of the river system in its entirety.

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© Copyright 2013 Megan Fylling