My inclination is to recommend building some housing for predators like hawks and owls if you're able and have the space. It's a nice way to address the varmint population while also meeting the need of being good for the local ecosystem, though it works slowly.

Ways we have accidentally concentrated our vole population include

• Creating brush piles of wood chips and sticks

• Growing nasturtiums

• Growing Jerusalem artichokes (Helianthus tuberosus)

But doing a combination of all three intentionally seems to have drawn their attention from the majority of the yard that isn't gardens, and by giving open space between the vole magnet area and our gardens it increases the chances for one of their predators to keep their numbers in check.