Microtus spp.
Small rodents that create surface runways and tunnel systems. Damage roots, bulbs, and bark. Often confused with moles but are herbivores.
Small mouse-like rodents, 4-8 inches including tail. Brown or gray fur, small ears, short tail. Surface runways 1-2 inches wide in grass. Small burrow holes.
Girdled bark at base of trees and shrubs (especially under snow). Damaged bulbs and root vegetables. Surface runways in lawn. Eaten roots and tubers.
Breed year-round, peak in spring and fall. Litters of 3-6 young every 21 days. Populations can explode rapidly. Active day and night.
Keep grass mowed short. Remove mulch from tree bases. Install hardware cloth guards on trees. Reduce ground cover near valuable plants.