Brad, when we bought Dulcamara, she was shrouded with netting, as Greg suggests. What I found was that whilst it worked, it was a real pain in the behind to put up and down each time we went sailing, so when we moved to Pittwater, we decided to use something else.
For a while, we used nothing, that worked and we only got an occasional drop from a wayward cormorant on the spreaders. Then, by father in law bought us an owl. This had the effect of being. A threat during the nesting season and all the local birds spent many fun hours dive bombing the owl, their preferred weapon was their own poo, which meant that the owl caused more poo than we had previously expended.
We then went to plastic shopping bags. They worked a treat, they were noisy enough to keep the boat bird and poo free, however they did break down and occasionally broke free, which is bad for the fishies. They took no time to tie on and off when going out. I was then advised that a rubber snake was the go, and so far I've had two. They used to live on the forward section of the cabin in front of the mast step. One was lost at sea on my trip to Lake Macquarie last year, the other was purloined by the local lads of Careel Bay, probably because it was a 6 foot green python and would have been really fun to throw at their teacher or little sister.
Since the last snake was nicked, I've not bothered with any preventative, and the boat is still poo free, so I'm not even sure if the snake was doing the job, or whether the birds just don't like our boat?
One thing is certain, the less you need to do to either get to the point of dropping your mooring to sail off, or pack your boat down to come home, the more pleasant your boat ownership and sailing experience will be. There is nothing worse than sitting at home thinking that it's too hard to go out sailing......
Now you get to choose who says too much on the forum, Mr Greg or me.... But wait until Bear gets going!