Date of Award

2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Natural Resources

First Advisor

Allan M. Strong

Abstract

Wildlife species that rely on early successional habitat are showing long-term region-wide declines, including songbirds such as Eastern Towhee (Pipilo erythrophthalmus), Field Sparrow (Spizella pusilla), Blue-winged Warbler (Vermivora cyanoptera), Golden-winged Warbler (Vermivora chrysoptera), Prairie Warbler (Setophaga discolor), and Brown Thrasher (Toxostoma rufum). All six species are listed as Species of Greatest Conservation Need on a majority of the New England state's Wildlife Action Plans and in 2011, the Golden-winged Warbler was placed under review for federal listing. In areas where vegetation structure is actively maintained in early successional stages, such as powerline rights-of-way (ROWs), there is an opportunity to provide habitat over long time frames. This study focused on habitat use by six early successional bird species in the Champlain Valley in Vermont along powerline ROWs. Thirty sites that included potential habitat were established. During the breeding season, trained citizen scientist volunteers spot-mapped species distribution patterns along transects. Focal habitat use by individuals was mapped during timed field observations (n=83). Vegetation species composition and structure was evaluated within 1m2 vegetation plots across each site (n=965). Logistic regression models of study species' abundance patterns and focal habitat use were compared using Akaike's information criterion (AIC). Surrounding landscape composition, vegetation species composition and vegetation structure had the greatest influence on species abundance and focal habitat use based on best-fit models. All species occurrence, except Blue-winged Warbler and Brown Thrasher, decreased with greater development and fragmentation in the surrounding landscape. While the covariates that influenced habitat use patterns by the species were similar, the effect size and direction of influence varied. These results suggest that a universal management approach for shrubland songbird habitat would not support a broad range of species. The findings from this study determined species-specific habitat preferences that can improve management practices to benefit these declining species.

Language

en

Number of Pages

76 p.

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