We had problems with birds in Florida and used CD's hanging off a line. A friend put spikes on the top of his mast which worked well also.

On passage about 50 miles offshore we had a Frigate bird resting on the wind transducer arm bending it to where I was concerned it would break. We tried to encourage it to fly away by banging the mast, shaking the rigging etc. It looked at us but didn't want to leave. Nothing worked although it did show it's distain by crapping more on the deck. The Admiral went below and brought up our 'wrist rocket' (slingshot). I lied on my back on the foredeck, took aim and let off a large steel ball bearing. I saw the shot just miss the bird whizzing by. It turned it's head at the sound probably wondering what the sound was but didn't fly away. Taking aim with the second shot I let go and it hit the bird directly in the breast Feathers ruffeled where the shot hit and the big bird looked at me. After what seemed like 30 seconds of thought and a bit of moving around it decided to leave (taking its time). It flew around our boat for 5 minutes looking to land again before flying away.

Damn big crappy bird.

A wrist rocket slingshot works well when you want a aingle bird to make the decision to move on. I was suprised at how hard the large steel shot hit the bird and how little it seemed to care.