A vole in a garden container. Photograph by Gilles Gonthier. Some rights reserved (view image details).

Voles: Adorable, or the enemy?

That cute little animal is a vole — the bane of every seedling tree’s existence. This small mammal, which is sometimes referred to as a meadow mouse or field mouse, is a relative of the mouse and thrives on small plants, including seedling trees.

Voles will often girdle young trees, or cut a ring around the bark, resulting in significant health impacts and eventual seedling death. They also eat succulent root systems and burrow underground, continuing to consume until the plant is dead. As if that isn’t bad enough (at least to seedling nurseries like ourselves), due to their excellent burrowing skills, the presence of voles can only be identified after a large number of plants have been killed.

So, why talk about voles? Because it was these animals that wiped out many trees that could have been in your hands this sales season. This year, the Colorado State Forest Service (CSFS) Nursery was victim to a major vole infestation that killed an appreciable number of trees of popular species.

If you’ve recently tried to order Colorado blue spruce from us, you may have already heard a shorter version of this story. This species got hit the hardest, with an estimated 7,000 seedlings killed before we realized what was happening. We were left with a mere 46 percent of our original estimated blue spruce inventory. Other species that were affected include:

  • Voles damaged a large number of seedlings at the CSFS Nursery.

    Engelmann spruce

  • Limber pine
  • Ponderosa pine
  • Austrian pine
  • Douglas-fir

Given their potential for destruction, we had to take preventive measures against these voles. We have leveraged poison blocks, sprayed the trees with a concentrated capsaicin mixture, and brought in feral cats to control the vole population. So far, the use of capsaicin has been the most effective and we hope the cats will prove helpful when released.

As of now, we have good crops of the aforementioned species coming in for the next season. We move forward with optimism and many lessons learned about the cute tricks nature has up its sleeve for seedling tree nurseries.

Notes from the Nursery is the Colorado State Forest Service Nursery’s quarterly newsletter

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