Response of brown-headed cowbirds and three host species to thinning treatments in low-elevation ponderosa pine forests along the northern Colorado Front Range

Forest Ecology and Management
By: , and 

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Abstract

Thinning ponderosa pine (Pinus ponderosa) forests to achieve desired ecological conditions remains a priority in the North American west. In addition to reducing the risk of high-severity wildfires in unwanted areas, stand thinning may increase wildlife and plant diversity and provide increased opportunity for seedling recruitment. We initiated conservative (i.e. minimal removal of trees) ponderosa stand thinning treatments with the goals of reducing fire risk and improving habitat conditions for native wildlife and flora. We then compared site occupancy of brown-headed cowbirds (Molothrus ater), chipping sparrows (Spizella passerina), plumbeous vireos (Vireo plumbeus), and western wood-pewees (Contopus sordidulus) in thinned and unthinned (i.e., control) forest stands from 2007 to 2009. Survey stations located in thinned stands had 64% fewer trees/ha, 25% less canopy cover, and 23% less basal area than stations in control stands. Occupancy by all three host species was negatively associated with tree density, suggesting that these species respond favorably to forest thinning treatments in ponderosa pine forests. We also encountered plumbeous vireos more frequently in plots closer to an ecotonal (forest/grassland) edge, an association that may increase their susceptibility to edge-specialist, brood parasites like brown-headed cowbirds. Occupancy of brown-headed cowbirds was not related to forest metrics but was related to occupancy by plumbeous vireos and the other host species in aggregate, supporting previous reports on the affiliation between these species. Forest management practices that promote heterogeneity in forest stand structure may benefit songbird populations in our area, but these treatments may also confer costs associated with increased cowbird occupancy. Further research is required to understand more on the complex relationships between occupancy of cowbirds and host species, and between cowbird occupancy and realized rates of nest parasitism.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Response of brown-headed cowbirds and three host species to thinning treatments in low-elevation ponderosa pine forests along the northern Colorado Front Range
Series title Forest Ecology and Management
DOI 10.1016/j.foreco.2013.06.037
Volume 306
Year Published 2013
Language English
Publisher Elsevier
Publisher location New York, NY
Contributing office(s) Fort Collins Science Center
Description 8 p.
First page 226
Last page 233
Country United States
State Colorado
County Boulder County
Online Only (Y/N) N
Additional Online Files (Y/N) N