This birdbath "fountain" is sure to be a hit with the flocks on your block.
Choose a level spot beneath a tree branch or some other overhanging structure. Arrange the rocks in the lid and fill with about 2 inches of water. Set the bath securely on a tree stump, rock or pedestal of cinder blocks.
Using a pushpin, poke a hole or two in the bottom of the bottle and, using the string, suspend the bottle a few feet over the bath. The water should drip steadily but not flow out of the hole, since birds are attracted to the sound of gentle dripping.