I have found a way of saving most of the mice that our cat brings into the house.
She normally brings them into the hall and puts them down by the front door during the night , then of course if we wake up we have to come to the rescue which can take ages especially when you've been asleep.
When we bought some new kitchen blinds that came in a long cardboard tube I cut it into lengths and laid it along the skirting board near the front door.
The mice immediately take shelter in a tube and the cat makes such a noise scrabbling about trying to reach them that we are woken quite quickly. Its then easy to pick up the tube covering the ends and slide the mouse gently out onto the lawn. (Having locked the cat in another room).
Fortunately the cat is too stupid to have realised what is going on and its quite funny to watch her peering down the tubes hopefully.
I wish I could find a better way of protecting them in the garden, any ideas would be welcome. Other than killing the cat of course!