Investigations of methods to reduce damage by voles

Voles (Microtus spp.), small burrowing rodents, range over much of North America. Populations cycle and achieve peak densities every 3-5 years. This can result in severe damage to various resources: orchards, forest plantings, alfalfa and other crops, ornamentals, lawns, and gardens. A variety of methods are used to reduce vole damage, but there is still a need for new, cost-effective, and environmentally benign approaches. We investigated numerous candidate repellents and barriers with indoor vole colonies in soil-filled tanks. Several compounds (blood meal, capsaicin, castor oil, coyote urine, quebracho, and thiram) showed promise as repellents, but only at high concentrations. Many other compounds were completely ineffective. Voles breached short physical barriers, either by climbing or burrowing. Taller barriers were less often breached by voles. Adding a repellent, coyote urine, inside the barrier increased barrier effectiveness. A tactile barrier, sand in acrylic paint, did not reduce vole gnawing hybrid poplar sticks. While some of these approaches appeared promising, field testing will be needed to determine the cost, effectiveness, and duration of protection under more natural conditions. Our findings are discussed within the context of an integrated pest management strategy to reduce damage by voles more effectively