Management strategies for the control of northern pocket gophers, Thomomys talpoides, in agro-Manitoba
Damages due to the activities of the northern pocket gopher (Thomomys talpoides) are estimated to cost Manitoba forage producers over $15 million annually, with similar losses estimated in Saskatchewan and Alberta. Losses across North America likely total several hundred million dollars annually. Pocket gophers consume forage plants below and above ground, and excavate subterranean tunnel systems, bringing excess soil to the surface, producing mounds. These mounds suffocate crops, damage machinery and cause immeasurable frustration for prairie forage producers. Objectives of this study were to (1)~determine loss in alfalfa yield due to pocket gopher consumption and damage, and whether this loss is economically significant; (2)~analyse the effectiveness of grass cultivated and treated buffer zones of varying widths on the control of pocket gopher invasion; and (3)~provide a method to determine the most cost-effective option(s) to farmers to control pocket gopher damage. Decreases in harvestable yield on plots occupied by pocket gophers were significant, with average losses of 22.9\%. Effectiveness of buffer zones varied between treatments; however, their use as configured in this study cannot be recommended at this time. A management strategy is outlined, incorporating the average yield loss of 22.9% and the cumulative costs of three control options; leaving the stand untreated, applying a rodenticide and re-establishing the stand every three years, over a period of 5 harvest years. When compared to the costs of no treatment, applying a rodenticide proved to be an economically viable option on the study site, whereas the costs of re-establishing the stand every three years was economically inefficient.