Voles are a small mammal mentioned briefly in the How to Train Your Dragon Book series.
Voles are a very small rodent related to mice, and sometimes even referred to as "field mice". They are, however, classed in the Subfamily Arvicolinae along with lemmings and muskrats. Physically they do greatly resemble mice, as well as some moles and have similar behaviors such as making burrows. Voles can give birth 5-10 times a year, balancing out their low position on the food chain. They are prey for a great many carnivorous species.
In the Book series, voles are prey for smaller dragon species.
|“||Toothless stopped trying to catch voles and leaped into the mud||”|
|— Book 1|
Though not mentioned in the actual story itself in this book, voles are mentioned in the dragon informational page for the Shortwing Squirrelserpent, as part of its diet.