The voles won't move on. They'll keep eating now and be back for seconds next year unless you take some control measures. I'd be out there with a shovel removing the snow around the other trees. Then I'd be looking for poison. Next year I'd be poisoning in fall. But I've never had voles so you may need other measures. Maybe some hardware cloth around the base of the trees.

This post was edited by fruitnut on Sat, Feb 22, 14 at 22:47

Spiral tree wraps, [tight] will do or paint.
Walk around an push snow down around trunk, Voles usually travel under the snow, [soft] until they found a meal.

I protect my new trees with 1/4" hardware cloth. I bury the bottom in the soil so they don"t go under it. If you live in a high snowfall area you would want the cloth to go above the snow line. Here in Missouri we don't usually get deep snows so mine is only a foot high.

Voles usually prefer a meadow like unmowed or disked place to have their underground homes. If this is what you have near your trees you will need to protect them.

If you choose to use poisoned bait for them. I've found it most effective to find their hole and put the bait near the entrance. They usually clean all of the grasses or plants in a line straight out of the main entrance so you have a good line to see to help find their holes.

Most of my experience dealing with them was in the central valley of California as a landscaper. No snow to deal with there so I don't know how winter long snow cover will change your experience.

I found that as the trees matured and put on bark they became protected from voles.

Good Luck.

We have both gophers and voles! We plant every plant in a gopher wire basket (a real pain), and surround each trunk 1-2' high with gopher wire. We haven't lost a tree yet!

36 in metal window screen the easiest and cheapest way to protect your trees

It is important, also, to maintain a weed-free area around tree. A hungry cat also helps.