It is actually heat that sets them off not motion. Thats why your not supposed to point them towards the rising or setting sun. I believe that grasses and leaves set them off because they are reflecting the sun's heat.
No, they have a motion sensor that triggers the camera. Maybe you're thinking of the cameras that are equipped with infrared lights and those are infrared LIGHTS not infrared SENSORS.
What type do you have?I have 3 Moultrie cams.Two are 4.0,the other is a 5.0 camo.I also have 2 Wildview 1.3 mp cameras.The Wildviews are terrible for limbs setting them off.A grouse won't set off my Moultries,but raccoons and larger will.
Bluejays set mine off all the time. Even chipmunks set mine off.



























