Capsicum-laden soils decrease contact time by northern pocket gophers

Fossorial rodents damage lawns/water impoundments/crops. We conducted a two-choice, parametric-type study to determine the effects of capsicum-oleoresin/soil mixtures (0.00, 0.75, 1.50, and 2.25%) upon soil-contact, soil-digging, and pelage-grooming behaviors in northern pocket gophers (Thomomys talpoides). In 3 alternate-day (1-h/day) exposures to > or = 1.50% capsicum-oleoresin soil mixtures, gophers decreased mean soil contact time by 46% relative to placebo-exposed animals. Grooming time yielded a concentration x trial interaction that showed intense grooming by capsicum-exposed animals during trial 1, with "convergence" of times to near those of the "placebos" (0.00% capsicum oleoresin) by trial 3. The significant decrease in grooming activity was attributed to the gophers' reduced contact with capsicum soil across repeated exposures, rather than to chemical habituation. Soil-digging behaviors were minimally affected. Results demonstrate the feasibility of deterring gopher habitation by mixing chemical irritants in soil.