The Trouble with Voles

Meadow Vole, side view. Image Credit: Japanese Tea, Wikimedia Commons

These wee, furry beasties are cute enough to look at. Voles belong to the order Rodentia and are similar in appearance to a short-tailed version of their relative the mouse. Some species, including the prairie vole, mate for life. With an average length of 5-6 inches, they are just about the right size to fit in the palm of an adult's hand--not that handling a wild rodent is ever recommended. Five different species of vole can be found in the Roaring Fork Valley alone (Huggins, 2004). They feed on seeds; grasses; forbs; fungi; and, apparently, wires.

Thus we come to the trouble with voles. They are not friends to long-term monitoring, at least not to the sensors that gather data. We suspected a threat might be crouching on the horizon last August when we noticed numerous holes dotting the ground during a siting visit for one our soil moisture and climate monitoring stations. During the installation of the site, suspicions were confirmed when I saw a small, brown shape shoot from one hole to another. It was a vole.  I did not get a clear enough view to say which of the Roaring Fork's five species graced our site with its presence, but I did see enough to know that rodent presence in the area might be a challenge to our data collection.

Right from installation, any exposed wire at the site was wrapped in reflective tape, a common method for deterring rodents. After the one sensor became damaged at the start of winter, I secured the remaining sensors in an additional 5 five layers of the aluminum tape.  The resulting bundle was as wide around as the pvc pipe used to protect the wires stretching from the tower to their monitoring location location. This measure was only sufficient until the end of winter. Last week, we made a repair visit to the site and found a pile of small rolls of aluminum tape  that had been plucked from the wires and flung about a 2-foot diameter radius in little, chewed-upon balls. In addition to removing the protective tape from the exposed section of wire, the voles had pulled a greater length of wire out of the PVC pipe to access further surfaces for chewing. The wires themselves had been completely chewed through. It was both distressing and impressive.

Science loves nothing like a challenge, however, and we were game for this one. Having preemptively armed ourselves with piping elbows, lengths of unused pipe, duct tape, and reflective tape, we removed the damaged soil sensors and replaced them with new equipment--now protected by an elaborate system of piping that descends underground to a depth of over 6 inches. 

By the end of the afternoon, storm clouds were beginning to scud in, bringing with them a biting wind. But before the rain and chill drove us out, we were able to burry new sensors (now successfully gathering data) and collect the damaged sensors for later repair. Previous splicing experience will soon be put to the test as we attempt to salvage our vole-ravaged wires.

Stringing the wires from the hole to the logger tower. Image Credit: AGCI, 2015

Sometimes research looks like a calm lab technician in a white coat surrounded by spotless beakers, sometimes it looks like someone intent on a computer screen running data through a newly designed modeling system, and sometimes it looks like a person lying on her stomach in the soil and spikey grass, taping wires with muddy fingers. All of these scenarios represent the earnest endeavor to better understand how this world works and the ways it may be changing over time. The one scenario we hope science does not look like any time soon is a charming little rodent with its mouth full of wire.

Reference:

Huggins, Jain Lindsey. 2004. Wild at Heart. WHO Press. Basalt, CO.