I have a plague of voles, hundreds of holes. Many of them are in rings around trees and I'm concerned because I know that in winter they will eat the bark and probably kill the trees. I've had my local pest control chap in and he'd never seen anything like it. He's put poison in some, but can't do several hundred. He said it would take several visits but how he'll know where he put the poison goodness knows. I cut the grass today and there are loads more holes
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I have a plague of voles, hundreds of holes. Many of them are in rings around trees and I'm concerned because I know that in winter they will eat the bark and probably kill the trees. I've had my local pest control chap in and he'd never seen anything like it. He's put poison in some, but can't do several hundred. He said it would take several visits but how he'll know where he put the poison goodness knows. I cut the grass today and there are loads more holes
We need more barn owls, they will eat the voles
but if they eat poisoned voles they too will die 
There's a shortage of barn owls - they tell us it's because of a shortage of bank voles due to the floods last year.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.