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Bird--Habitat Relationships in Interior Columbia Basin Shrubsteepe

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Title Bird--Habitat Relationships in Interior Columbia Basin Shrubsteepe
Names Earnst, Susan L. (creator)
Holmes, Aaron L. (creator)
Date Issued 2012-02 (iso8601)
Note To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.
This is the publisher’s final pdf. The published article is copyrighted by Cooper Ornithological Society and can be found at: http://www.cooper.org/.
Abstract Vegetation structure is important in structuring avian communities. In the sagebrush biome, where
continued habitat loss is thought to threaten shrusteppe-obligate birds, both remotely sensed and field-acquired
measures of big sagebrush (Artemisia tridentata) cover have proven valuable in understanding avian abundance.
Differences in structure between the exotic annual cheatgrass (Bromus tectorum) and native bunchgrasses are
also expected to be important. We used abundance from 318 point-count locations, coupled with field vegetation
measurements and a detailed vegetation map, to model abundance of four shrub- and four grassland-associated
avian species in southeastern Washington. Specifically, we ask whether species’ abundances in bunchgrass and
cheatgrass differ and whether mapped categories of cover adequately explain species’ abundances or whether finegrained,
field-measured differences in vegetation are also important in explaining abundance. We found that the
abundance of shrub associates did not differ in sagebrush with a cheatgrass vs. bunchgrass understory, but grassland
associates tended to use bunchgrass more than cheatgrass grasslands (Horned Lark, Eremophila alpestris;
Grasshopper Sparrow, Ammodramus savannarum), or, in one case, cheatgrass more than bunchgrass (Long-billed
Curlew, Numenius americanus). In the comparison of map- and field-based models, mapped cover types alone
were sufficient for predicting abundance of five species studied, but models containing field-measured sagebrush
cover outperformed models based on maps only for three species, the Sage Sparrow (Amphispiza belli) (+), Horned
Lark (–), and Grasshopper Sparrow (–). We conclude that cover-type maps that consider understory composition
and sagebrush density can predict avian distribution and abundance in the sagebrush biome efficiently.
Genre Article
Topic Artemisia
Identifier Earnst, S. L., & Holmes, A. L. (1900). Bird-habitat relationships in interior columbia basin shrubsteppe. The Condor, 114(1), 15-29. doi: 10.1525/cond.2012.100176

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