Community- and landscape-level responses of reptiles and small mammals to feral-horse grazing in the Great Basin
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Authors: E. A. Beever, and P. F. Brussard
Date: 2004
Journal: Journal of Arid Environments
Volume: 59
Number: 2
Pages: 271-297
Summary of Methods: The effects of feral-horse grazing on the species richness and abundance of reptiles were investigated along two elevational strata (high and low-elevation) across nine mountain ranges of the western and central Great Basin. Nineteen sites were selected to fit into two treatments (feral horses present and feral horses removed for 10-14 years). The number of small mammals and squamate reptiles captured were recorded over two years.
Article Summary / Main Points: Sites where feral horses had been removed had a greater number of species present. In the first year, eight of the 21 (including 14 nocturnal rodents) captured species were found exclusively at sites where horses were removed, with no species exclusive to horse occupied sites. During the second year, five of the 20 (including 13 nocturnal rodents) captured species were exclusively located on sites where horses had been removed, while two species were exclusively located on sites with feral horses grazing. Areas where feral horses have been removed have a higher RRR (realized richness of rodents) than occupied feral horse sites. There was no considerable difference between reptiles in these two areas. Sites at high elevations averaged only 1.75 individuals per site and had at most one species.
Vegetation Types: Sagebrush Steppe
MLRA Ecoregions: 24 Humboldt Area 26 Carson Basin and Mountains 27 Fallon-Lovelock Area 28B Central Nevada Basin And Range
Agrovoc Control Words: Horses Herbivory Wildlife
Article Review Type: Peer Reviewed
Article Type: Experimental Research
Keywords: granivorous small mammals, great basin, feral-horse grazing, equus caballus, species pools, reptiles, pocket mouse, peromyscus maniculatus, sagebrush
Annotation: The results from this two year, replicated study are applicable across many rangelands that are grazed by feral-horses. This is a strong study with 19 sites being evaluated from western great basin. The specific results may vary as the Great Basin did not evolve with a population of grazing herbivores. This study suggests that climatic variations did not eclipse effects imposed by horses on semi-arid ecosystems. Based on the experimental design used, the top priority for future studies of synecology of horse grazing should be the incorporation of manipulative experiments of horse density. Feral horses exhibit different watering behavior in arid systems and therefore, more studies at springs and other watering areas may help in understanding the priorities for future protection efforts in riparian areas. Also, the study did not capture and tag reptile individuals. Therefore, studies on the relationship between horse grazing and reptile abundance using field methods focused exclusively on reptiles, is very important.
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