Feeding critters from home

I learned something this weekend... back up a bit here. For starters, I like birds, though contrary to what my lovely wife might say, I am not a "birder". Anyhow... I put up birdfeeders on my front porch and have had managed to attract over a dozen species of birds including a chicken hawk who had a finch-feast last season. Recently, the finches and sparrows have been swarming my porch. At any one time, there may have been 50+ easily there.

Over the last year or so, I have been battling squirrels and solved my squirrel problem by trapping and relocating them. If I don't trap them, they gorge on the birdseed, get fat and sow and get killed on 15th street. So, by relocating them, I'm doing them a favor.

What I hadn't anticipated were mice. I saw a couple of them on the porch eating the dropped birdseed and decided to investigate further. What I found was a mouse mini-colony living in my planter boxed also on the porch. It's a short trip from the porch into my house. Squirrels torque me off but I'm somewhat nice to them; mice, on the other hand don't get any mercy. After savagely catching and killing 9 (at least 3 escaped). Methinks the vermin have won. The birdfeeders have been moved to the backyard. No more birds on my porch for a while.

So, any suggestions on how to keep the mice away?