Landscape and local effects on occupancy and densities of an endangered wood-warbler in an urbanizing landscape

Landscape Ecology
By: , and 

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Abstract

Context

Golden-cheeked warblers (Setophaga chrysoparia), an endangered wood-warbler, breed exclusively in woodlands co-dominated by Ashe juniper (Juniperus ashei) in central Texas. Their breeding range is becoming increasingly urbanized and habitat loss and fragmentation are a main threat to the species’ viability.

Objectives

We investigated the effects of remotely sensed local habitat and landscape attributes on point occupancy and density of warblers in an urban preserve and produced a spatially explicit density map for the preserve using model-supported relationships.

Methods

We conducted 1507 point-count surveys during spring 2011–2014 across Balcones Canyonlands Preserve (BCP) to evaluate warbler habitat associations and predict density of males. We used hierarchical Bayesian models to estimate multiple components of detection probability and evaluate covariate effects on detection probability, point occupancy, and density.

Results

Point occupancy was positively related to landscape forest cover and local canopy cover; mean occupancy was 0.83. Density was influenced more by local than landscape factors. Density increased with greater amounts of juniper and mixed forest and decreased with more open edge. There was a weak negative relationship between density and landscape urban land cover.

Conclusions

Landscape composition and habitat structure were important determinants of warbler occupancy and density, and the large intact patches of juniper and mixed forest on BCP (>2100 ha) supported a high density of warblers. Increasing urbanization and fragmentation in the surrounding landscape will likely result in lower breeding density due to loss of juniper and mixed forest and increasing urban land cover and edge.

Study Area

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Landscape and local effects on occupancy and densities of an endangered wood-warbler in an urbanizing landscape
Series title Landscape Ecology
DOI 10.1007/s10980-015-0250-0
Volume 31
Issue 2
Year Published 2015
Language English
Publisher Springer
Contributing office(s) Alaska Science Center Biology WTEB
Description 18 p.
First page 365
Last page 382
Country United States
State Texas
County Travis County
Other Geospatial Balcones Canyonlands Preserve
Online Only (Y/N) N
Additional Online Files (Y/N) N