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Open Access Publications from the University of California

Control of the Oregon ground squirrel (Spermophilus beldingi oregonus)


Attempts to reduce populations of Spermophilus beldingi oregonus have centered around the application of Compound 1080 and strychnine baits. Additional population reduction techniques were investigated for possible employment into the squirrel program. Techniques which show much promise are: hand baited chopped green bait (.01% chlorophacinone), broadcast (10 pounds per acre) and hand baited grain bait with .01% chlorophacinone and .05% fumarin, and bait stations using .01%, .05% chlorophacinone grain bait (100 and 200 foot spacing) and .05% fumarin grain bait (100 foot spacing). In addition, the concentration of Compound 1080 on chopped green bait can be reduced to 1/4 oz. of 1080 per 250 pounds of chopped green bait broadcast at 10 pounds per acre. Preliminary investigation in damage assessment using exclusion cylinders resulted in 123 squirrels per acre removing an average of 1,790 pounds (spring growth alfalfa - downy broom) per acre in 44 days. Stomach content weights were determined over a 3½-month period. Feeding behavior and average daily food consumption is greater early in the year (May) than later (July).

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