I would like to develop a motion activated sprinkler to deter birds (cranes and other smaller birds) and small animals from eating the fish in my pond. I am using the approach of controlling a solenoid valve via a PIR motion sensor. However, this means the thing will activate even if humans walk past it.
Is there any method to trigger it only for motion by small animals (say less than 2.5 ft height)? I'm open to suggestions on entirely different sensors/methods.
Based on some pet friendly intrusion alarm websites, it looks like there may be PIR sensors that can be tuned to differentiate between animals less than 50 pounds vs more. I just can't seem to find the existence of such sensors.