Detectability adjusted count models of songbird abundance: Chapter 6

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Abstract

Sagebrush (Artemisia spp.) steppe ecosystems have experienced recent changes resulting not only in the loss of habitat but also fragmentation and degradation of remaining habitats. As a result, sagebrush-obligate and sagebrush associated songbird populations have experienced population declines over the past several decades. We examined landscape-scale responses in occupancy and abundance for six focal songbird species at 318 survey sites across the Wyoming Basins Ecoregional Assessment (WBEA) area. Occupancy and abundance models were fit for each species using datasets developed at multiple moving window extents to assess landscape-scale relationships between abiotic, habitat, and anthropogenic factors. Anthropogenic factors had less influence on species occupancy or abundance than abiotic and habitat factors. Sagebrush measures were strong predictors of occurrence for sagebrush-obligate species, such as Brewer’s sparrows (Spizella breweri), sage sparrows (Amphispiza belli) and sage thrashers (Oreoscoptes montanus), as well as green-tailed towhees (Pipilo chlorurus), a species associated with mountain shrub communities. Occurrence for lark sparrows (Chondestes grammacus) and vesper sparrows (Pooecetes gramineus), considered shrub steppe-associated species, was also related to big sagebrush communities, but at large spatial extents. Although relationships between anthropogenic variables and occurrence were weak for most species, the consistent relationship with sagebrush habitat variables suggests direct habitat loss and not edge or additional fragmentation effects are causing declines in the avifauna examined in the WBEA area. Thus, natural and anthropogenic disturbances that result in loss of critical habitats are the biggest threats to these species. We applied our models spatially across the WBEA area to identify and prioritize key areas for conservation.

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Additional publication details

Publication type Book chapter
Publication Subtype Book Chapter
Title Detectability adjusted count models of songbird abundance: Chapter 6
Chapter 6
ISBN 978-0-615-55530-0
Year Published 2011
Language English
Publisher Allen Press
Publisher location Lawrence, Kansas
Contributing office(s) Forest and Rangeland Ecosystem Science Center, Fort Collins Science Center
Description 80 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Sagebrush ecosystem conservation and management: Ecoregional assessment tools and models for the Wyoming Basins
First page 141
Last page 220
Country United States
State Wyoming
Online Only (Y/N) N
Additional Online Files (Y/N) N