Voles are small, stocky rodents with short tails and inconspicuous ears, often mistaken for mice or moles. These herbivorous mammals are native to North America and Eurasia, primarily feeding on grasses, roots, and bulbs. Voles remain active throughout the entire year, unlike rodents that hibernate, necessitating constant foraging. Understanding their activity patterns is key to recognizing their presence.
Understanding Vole Daily Rhythms
Voles exhibit a polyphasic activity pattern, meaning they are active in multiple short bursts throughout the 24-hour cycle. This pattern is linked to their high metabolic rate, which demands a nearly continuous intake of food. Activity often follows ultradian rhythms, with cycles of activity and rest occurring every one to six hours.
While voles can be observed at any time, their activity typically peaks during the crepuscular hours around dawn and dusk. This preference offers protection from predators that hunt during full daylight or deep darkness. However, finding voles foraging during the middle of the day is common, especially in areas with dense vegetation that provides cover. The need to constantly graze overrides a strict adherence to a nocturnal schedule.
Seasonal Behavioral Shifts
Vole activity levels change significantly with the seasons, driven primarily by temperature and food availability. During the warmer spring and summer months, voles spend more time above ground, creating a visible network of surface runways in the grass. Their diet focuses on fresh green vegetation, forbs, and seeds.
Winter activity centers on the subnivean zone, the insulated space between the ground and the snow layer. Snowpack acts as a thermal blanket, keeping this zone consistently near 32°F (0°C), allowing voles to forage safely. This hidden activity involves tunneling to reach food sources like bark and stored roots, which is why damage often only becomes visible after the spring snowmelt.
Peak Activity and Population Increase
Vole presence and resulting damage are strongly influenced by their reproductive capacity and subsequent population density. Voles can breed year-round, but the main reproductive season begins in late winter or early spring and continues through the fall. The gestation period is short (about 21 days), and females can reach sexual maturity in just over a month.
This rapid breeding leads to multiple litters per year, causing populations to increase exponentially under favorable conditions. The highest density of voles, and the most visible damage, usually occurs in the late summer and fall after several generations have matured. The annual peak of activity is directly tied to the abundance of young voles during the later part of the growing season.
Recognizing Evidence of Recent Activity
Even when not directly observed, several signs indicate ongoing vole activity in a yard or garden. The most distinctive evidence is the presence of narrow, well-worn surface runways, paths about one to two inches wide through the grass. These pathways are kept clear of obstructions and often contain small, rice-like droppings.
Voles also create small, golf-ball-sized burrow entrances near these runways, which lack the soil mounds associated with moles. Evidence of feeding includes small, irregularly spaced gnaw marks on the bark of young trees and shrubs near the base. When this gnawing completely encircles the trunk, it is called girdling, which can be fatal to the plant.