what about a sprinkler set on a motion sensor? You can put them on a timer so that they are only on at night or have a manual shut off so that if you know you don't want it on for a while you can turn it off.

We are installing one to hopefully keep the elk out of our garden until we can get our fence up. The elk were terrible on our garden last year. But we have two kids so we have to be able to turn it off when we know the kids are in the backyard.

I really don't know anything about where to buy them or what brand name. But I do know they exist and are supposed to be easy to install.

i hope you find some solution. Good luck.

Kristie