Proceedings of the Vertebrate Pest Conference

This paper updates control operations in Modoc County, in northeastern California, for the Oregon or Belding ground squirrel, Spermophilus beldingi oregonus. With the increase of sprinkler irrigation and continual improvement in farming methods, we are giving the ground squirrel a better environment: the squirrels have more food and moisture, and their juvenile survival rate appears to have continued to increase. As in earlier years, we still have problems with bait-shyness or poor bait acceptance. It is now virtually impossible to obtain adequate acceptance of grain baits, forcing us to use “green” baits. Dandelion is the bait that is best accepted by the squirrel, but it is hard to obtain at the right time and in sufficient quantities. Cabbage is the next best green bait, and it is practical and economical to use. In 1972, we started treating fields using 1080-treated cabbage, and treatments resulted in 95% to 99% squirrel control. For efficiency, aircraft broadcasting has become the common method of application. This baiting program is quite effective, but it is not the cure-all. We still have several unresolved problems. We have fields in which squirrel control is so effective we can skip two or three years before retreating; however, other fields must be treated annually. In some cases, squirrels move in from nearby areas. Some problems with bait acceptance continue.