Irene Shonle, CSU Extension, Gilpin County.  At this time of year, there is a great flurry of activity in many people’s yards. There are chipmunks scurrying to stash enough food for winter, juvenile birds still trying to cadge a meal off their parents, bears sniffing around for any kind of food they can find, and strange mounds and holes appearing in the ground at the same time that plants disappear.

I get a lot of questions about this damage, and what to do about it. The first step is to figure out which animal is causing the damage. The main two types of burrowing animals up here are voles (5 species) and pocket gophers (1 species). Contrary to popular belief, moles do not live up here – they barely come in to Colorado at all, and only then in the very eastern plains.

Voles

While this year has been a very bad year for voles, they are often blamed unfairly for the damage that pocket gophers have caused. People will often have both voles and pocket gophers on their property. However, since the voles are above ground and can therefore be seen, and pocket gophers spend 99% of their time underground, pocket gophers somehow fly under the radar.

Voles cause several types of damage. As they dig burrows, they create small, open holes 1-2 inches wide, and there is usually a “pathway” coming from it. They will clip off the tops of perennials, and wreak havoc in the vegetable garden. They can also gnaw on the bark of trees and shrubs, sometimes girdling them entirely and causing their death. Shrub and tree damage occurs in the winter when voles move through their runways under the protection of snow. The damage consists of irregular patterns of gnaw marks about 1/16 to 1/8-inch wide. They don’t typically eat the roots of plants.

Pocket gophers

Pocket gophers are much more destructive than voles. They create large mounds of soil on the ground and eat the roots of plants. Since the young are being kicked out of their mamma’s burrows right now, there are lots of new mounds appearing. Some people are seeing pocket gophers invade their yards for the first time!

The mounds that pocket gophers create are fan-shaped to round and usually have closed entrances.

The main signs of damage from pocket gophers include the soil mounds, eskers (solid tubes of soil) above ground when the snow melts in the spring, and suddenly wilting plants (due to root damage). If you walk across an area inhabited by pocket gophers, your foot will frequently break through into their tunnels.  The tunnels are usually 2.5-3.5 inches  in diameter, and are usually found in the top 4-18 inches of soil.

The CSU Gilpin County Extension Office is located at the Exhibit Barn, 230 Norton Drive, Black Hawk, CO 80422, 303-582-9106, www.extension.colostate.edu/gilpin. Colorado State University Extension provides unbiased, research-based information about, horticulture, natural resources, and 4-H youth development. Colorado State University Extension is dedicated to serving all people on an equal and nondiscriminatory basis.