These traps are designed for the Richardson ground squirrel( Gopher).They also work well for any ground squirrel that has an external entrance to their burrow,and that feed above ground,and are similar in size.We have great reports back using our traps for control of Belding, Thirteen stripe, Columbian, and North American brown in addition to the Richardson. We have mixed reports for Pocket gophers. Some have reported good results when placing a five gallon bucket upside down over the set to keep the light out.
Also please keep in mind that the Richardson ground squirrel adults hibernate starting with the adult males in July and the females in August. Only the spring born males will be active until freezeup. I trap with 250 traps on tame hay land and trapping success after July 15th dropped to 10% of my normal catch the previous 3.5 months.
The greatest trapping success, and the most damage done (before the young can live on their own) is by far late March, April and May.