California Vole Extravaganza


A very common yet seldom seen animal of Little Lake Valley is a small rodent called the California vole (Microtus californicus). They are often mistaken for mice and are commonly referred to as ‘meadow mice.’ California voles are overall brown in color with a lighter gray underside. Its tail is also bicolored, brown on top and light gray on the bottom.

While walking through the tall grass meadows on the Willits Mitigation Project, I catch glimpses of small brown flashes darting across the narrow alleyways that create an extensive network that crisscross throughout the fields of matted down grass and vegetation. These ‘vole highways’ connect to underground burrows, where they spend most of their time. California voles dig burrows that range from 5 – 40 feet in length. Voles will also sometimes utilize abandoned gopher burrows. They have a very small home range, or territory, averaging around 1000 square feet. Males roam further from their burrows than the females do and will defend their territories from other males but will not act aggressively toward other females their territories overlap with.

Voles use the above ground runways to find food and will stand on their hind legs to clip grass stems with their teeth to access the seeds at the top. They eat a variety of vegetation depending on the season. During the summer California voles will forage for grasses, sedges, seeds, and forbs. Over winter, voles will switch to roots and tubers. The quick flashes of brown I’ve been seeing are foraging voles that I have surprised as they furiously try to make it back to their burrows!

Breeding occurs throughout the year, but it ceases in periods of drought. In our Mediterranean-type climate, reproduction is typically restricted to the wet season between mid-September and early June (Cudworth and Koprowski 2010). Nests are constructed with dried grass in the burrows. Females have multiple litters (an average of six) in a year and gestation lasts for twenty-one days. The litter consists of 3 – 6 altricial young that are blind and hairless at birth. Their growth is rapid. After two weeks their eyes are open and then weaning follows soon after. Females reach sexual maturity within a month and then begin having their own litters. The lifespan of a vole is very short, on average one year.

The California vole is common and widespread so therefore has many predators it must avoid. Hawks, Barn Owls, egrets, coyotes, skunks, and garter snakes to name a few all prey on the small mammal. Although they are rarely seen, voles are an integral part of a functioning ecosystem. They help to recycle nutrients back into the ground and increase interactions between plants and soil bacteria. Additionally, voles provide a solid food base for the myriad of wildlife higher in the food chain.

Next time you find yourself in the middle of an open grassland, don’t forget to look down and attempt to have a vole sighting!