When I've started looking for information about the voles, I've found mostly the sites and Youtube videos about their extermination as an annoying pest. Well, I guess it depends on where you live, and what kind of voles and plants you have.
For all I can tell, the voles I have living in my yard are Townsend's voles (at least to my best interpretation of the information from the internets), and for all I can tell, they like eating grass. And in the Seattle area the grass is always green. Even if it snows, the grass is still green under the snow. It might not grow much in the Winter but it stays green. They don't seem to be over-eating the grass either. None of those runways chewed in the grass that I've seen in the videos from England. I haven't seen them eating the bark or tulip bulbs. I've seen a rabbit eat leaves off a young grape plant but not voles.
They do make a lot of holes and runways under the grass but these have no mole-hills, and aren't really visible (though in the areas of open dirt you can see the raised sections). Pretty much the only time I notice them is when I step on them and they collapse with that squishy feeling.
I actually see the voles as my allies against the moles. The moles are real annoying with their hills that kill the grass under them, and I try to poison them. I hope that if the area is taken by voles, the moles won't be able to claim it. This seems to work, not perfectly but work. After I've poisoned the moles, that area had gained a lot of vole holes, and the moles don't seem to spread so fast. They still try to expand from the neighboring areas but at a slower rate.
I guess the only way the voles get annoying is by digging their holes under the concrete. And then the rainwater gets in there and can eventually cause the concrete to shift. When I've bought the house, the steps slab at the front door was tilted, and it took the pumping of the polymer foam to straighten it. I've tried plugging some holes with gravel (and here "gravel" consists for some reason of pretty sizable roundy pebbles) and they would just dig it out.
The first owners of my property really liked the artsy gardening, so they've had a lot of concrete tiles spread around, I guess for some sculptures of flower pots. Then it all got overgrown under the next owners, and I've been finding those tiles as I was cleaning it up. Every time I'd lift a tile there would be the vole burrows under it (nothing fancy like nests, just some paths for running through).
If you see this kind of voles as pests, I think your only option would be some kind of mechanical traps without bait. I've tried giving different kinds of fruit to the voles I've caught, and basically they don't like it, they prefer grass. I've seen videos with voles eating an apple but our voles just poop on it at best. They do seem to eat nuts (so far I've tried pistachios and cashews) but not very enthusiastically, so a nut might or might not work as a bait. A different way to approach it would be to cut the grass short and to avoid planting trees and bushes close to the buildings, to make hiding from the predators more difficult.
If you want to catch a vole for fun, like I did, then letting your grass grow longer once in a while does help. More on this later.
