Get a statue of a big owl like this one and put it on a post in your yard... that'll keep them away.
No clue if it would work, but they may be afraid of owls or hawks. Can always try something like this: https://www.amazon.com/Gardeneer-Dalen-Natural-Scarecrow-Horned/dp/B00002N8HZ/ref=sr_1_4?ie=UTF8&qid=1472505694&sr=8-4&keywords=fake+owl+for+garden
It's similar to this
Keeps birds from building nests up there.
this is the answer.
http://www.amazon.com/Gardeneer-Dalen-Natural-Scarecrow-Horned/dp/B00002N8HZ
http://www.amazon.com/Gardeneer-Dalen-Natural-Scarecrow-Horned/dp/B00002N8HZ
something like this, the shop I work at put these up near our bay doors no more birds crapping on trucks.
Put up an owl decoy nearby. It will scare away the birds without harming them.