When my neighbours' cat got in my yard, I just yelled at it and whacked the side of my house with a broom to scare it away. Mom used to let my sister and I pour salt on the slugs in her garden when we were kids.
It took me less than five minutes to find
the David Suzuki Foundation's list of eco-friendly ways to keep cats out of your yard.As for coyotes, not only would messing with them probably be a bad idea even if you didn't have any housepets with you, but I think they keep the local rabbit population down in my part of St. Albert.