Use a drill or screwdriver to pierce four holes in the top of the plastic jug. Place the holes an inch from the top of the jug, with one hole on each side of the jug.
Cut two pieces of thick wire to be 6 feet long each. Fold each piece of wire in half.
Run one doubled piece of wire through one of the holes and out of the opposite hole. String the wire through until the ends poking out of each side of the jug are equal in length.
Run the second piece of wire through one of the other open holes and out through its opposite hole. Pull it through the second hole until both ends are equal in length. You should have one piece of wire coming out of each side of the jug.
Gather all four wire ends over the top of the jug. Twist them around one another four or five times, until you have a secure wire handle.
Use a sharp knife or box cutter to cut an opening out of one side of the jug. The opening should be large enough for birds to fit through, or about 3 inches square. Use the knife to cut a few 1/2-inch long slits in the bottom of the jug to allow rainwater to escape. Pour birdseed into the jug so it covers the bottom inch of the jug.
Hang the wire hanger over a tree branch. Every few days, empty the feeder, wash it out with soapy water and refill it with new seed.