I have a lot of voles on my plot. They have been quite a problem this year nibbling the skins of squash, and eating beetroot and chard roots during late autumn. I have been using mypex and silage sheet to enlarge the plat, which they do seem to enjoy to living under. I’ve use traps with peanut butter or nutella but a lot of voles remain.
Perhaps encouraging owls with suitable nest boxes could be a way of reducing the numbers?
The barn owl trust are an interesting group and I think owls like to eat voles.
http://www.barnowltrust.org.uk/content_images/pdf/Nestboxes_for_use_on_Trees1357645529.pdf
Andy