I have a few stobs sticking above the water that they love to perch on, so I've found wrapping scare tape around it and letting some hang loose is effective. You don't want just to wrap it around the stob, nor have so much tape that it lays flat on the water. You want it to flap in the breeze unrestricted, making noise & flashing in the sunlight.
Tree trunks close to favorite bird spots also work. If birds are really bad, you might hammer in a post where the water turkeys congregate and fly the tape there, too.
The tape doesn't last forever, but we found most of it was ok four to six months. Seemed to work better than the scare eye balloons, at least at our place.
