Hit him with as much water as you can all at once. He is heavy from not having exercise, and the water throws him off enough to ground him for a bit. Do not drench just before dark unless you are sure you can get him. If possible contact organizations 50 miles away. Sometimes people find them while traveling and go home with them.
Many birds can also get that far just flying.
Give all the children in the neighborhood a buck and tell them there is more if they can locate your bird. Kids tell on people that are hiding them also. Police will not help you retrieve a bird from someone else's home. You have to plan that one very carefully if they decide they want to keep your bird. There are no questions then about ownership.