I bought one of those Bunnings hawks to scare off Noisy Miners that attacked their own reflections in a glass door from dawn til dusk.
The Bunnings hawk was useless and became more of a launch pad than a deterrent.
We hung some shiny metallic spiral thing that glistens in the sun and twists with the wind. The farking Miners shit themselves and haven't been back.
It doesn't seem to have the same effect on pigeons though.
Worth a try with ducks.