Vesper Sparrows and Western Meadowlarks Show a Mixed Response to Cattle Grazing in the Intermountain Region of British Columbia

Avian Conservation and Ecology

Nancy A Mahony,¹  David J Green,²  AliciaNewbury,²  Megan L. Harrison,²  PatRobinson,³ 

[1] Wildlife Research Division Science and Technology Branch Environment Canada;Centre for Wildlife Ecology Department of Biological Sciences Simon Fraser University;Wildlife Research Division Science and Technology Branch Environment Canada

关键词: grassl;    birds;    grazing effects;    Pooecetes gramineus;    Sturnella neglecta;    Vesper Sparrow;    Western Meadowlark;   

DOI  :  10.5751/ACE-00358-050101

学科分类：社会科学、人文和艺术（综合）

来源: Resilience Alliance Publications

【 摘 要 】

Livestock grazing in the shortgrass steppe of the Intermountain region of British Columbia is predicted to have significant effects on grassland habitats and their associated ground-nesting bird communities.We tested whether grazed and ungrazed sites could be discriminated on the basis of their vegetation communities, whether the abundance of two ground-nesting bird species, Vesper Sparrow (Pooecetes gramineus) and Western Meadowlark (Sturnella neglecta), differed between grazed and ungrazed sites, and whether vegetation variables found to differ between grazed and ungrazed plots could be used to predict the abundance of the two bird species at a fine scale.Grazed sites were easily distinguishable from a site that had been ungrazed for >30 years based on the structure and composition of their vegetation communities.However, more detailed grazing categories could not be distinguished on the basis of vegetation characteristics.Despite the existence of grazing effects on vegetation structure and composition, we found no consistent differences in abundance of Vesper Sparrows and Western Meadowlarks between the grazed and ungrazed sites.However, there was weak evidence that the abundance of both species was higher at fine-scale plots (100 m radius point count station) with less bare ground and taller vegetation.Bare ground cover was lower on grazed plots, but vegetation was taller on ungrazed plots. Combined, our results suggest that low intensity grazing leads to grassland habitat change with both negative and positive effects on Vesper Sparrows and Western Meadowlarks, resulting in no net change in their broad-scale abundance.

【 授权许可】

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