Take an eye dropper or plastic pipette full of water. Put a drop or two on the top of his beak. It will run down into his mouth and he will swallow it. It takes a minute or two to get him to take the whole dropper full, but it is the safest way to get him to take fluids without it going into his lungs. If he is eating anything, you can take a bit of bread soaked in water. He might eat that on his own, getting some water, too.