Refining the control of northern pocket gophers (Thomomys talpoides) in agro-Manitoba

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Dubois-Claussen, Melanie
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The northern pocket gopher is a serious pest in Manitoba forage fields. It is estimated that damages to forage crops and harvesting machinery exceeds $15 million annually (estimated in 1996). The objectives of this study were to (1) develop an accurate census method for northern pocket gophers; (2) to study burrow ranges and movements of the northern pocket gopher; (3) to evaluate the efficacy of a zinc phosphide rodenticide on northern pocket gophers; (4) to compare the performance of two artificial burrow building machines; and (5) to provide management recommendations for forage producers. A census method with a time period of three days was the most efficient, with an acceptable level of accuracy of 92.3%. Burrow ranges of Manitoba northern pocket gophers were found to be similar to those described in the literature. A male that was radio-collared had a range double the size of the collared female. The zinc phosphide rodenticide (B.O.B$\sp\circler),$ reduced mounding activity by 38%-61%, and B.O.B$\sp\circler$ is recommended for application in the spring at a rate of 6.6 kg/2.5 ha with the Gofer$\sp\circler$ burrow builder. A management decision worksheet was developed and is outlined in a user-friendly format, designed for forage producers. This worksheet allows for quick determination of the most cost-effective method of controlling northern pocket gophers.