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CAN TOWNSEND'S GROUND SQUIRRELS SURVIVE ON A DIET OF EXOTIC ANNUALS?

Eric Yensen and Dana L. Quinney
The Great Basin Naturalist
Vol. 52, No. 3 (SEPTEMBER 1992), pp. 269-277
Stable URL: http://www.jstor.org/stable/41712727
Page Count: 9
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
CAN TOWNSEND'S GROUND SQUIRRELS SURVIVE ON A DIET OF EXOTIC ANNUALS?
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Abstract

Southwestern Idaho desert shrub-bunchgrass rangeland is being invaded by fire-prone exotic annuals that permanently dominate the landscape following wildfires. This study was undertaken to describe diets of Townsends ground squirrels (Spermophilus townsendii idahoensis) at four study sites with varying degrees of exotic annual invasion to determine if the squirrels could utilize high proportions of exotic annuals in their diets. Townsends ground squirrels were collected in March and May of 1987 and 1988, and stomach contents were analyzed using a microhistological technique. Grasses comprised 37-87% of Townsends ground squirrel diets at the four sites. Native species, especially Sandbergs bluegrass (Poa secunda), winterfat (Ceratoides hnata), big sagebrush (Artemisia tridentata) and six-weeks fescue (Vulpia octqflora) constituted 7-96% $\left( {\bar x = 47.2\% } \right)$ of the diet, whereas exotic species, especially cheatgrass (Bromus tectorum), tumbleweed (Salsola iberica), and tansymustards (Descurainia spp.) made up 4-68% $\left( {\bar x = 48.0\% } \right)$ of the diet. At each site 2-4 species comprised > 90% of the diet. There was no apparent correlation between the importance values of exotic species at a site and their importance in Townsends ground squirrel diets.

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