If you have problems with outdoor pests (including feral or neighborhood cats) try these great humane deterrents: ScareCrow works with a jet of water and Pest Repeller Ultimate uses ultrasonic sound waves.
The Scarecrow Sprinkler is a motion-activated sprinkler with an age-old concept. Contech Electronics has taken the scarecrow out of the ground and placed it on top of a sprinkler head. The sprinkler acts as a deterrent in the garden or
Contech Electronics scarecrow motion-activated sprinkler for humane animal deterrence Scarecrow detects and sprays animals in a area day and night Lightweight plastic shaft; metal sprinkler head Includes sprinkler mount and motion detector