Call your local city or district court and ask what needs to be done to get a restraining order.
I've had to get them twice before and in my area, there were forms online I could fill out.
Putting a RO in place BEFORE he files a law suit is your best protection, especially if his son is a...
Maybe build a potato canon to control the pigeons?
Just kidding, sort of.
If the real problem is the pigeons, does the city/county/DNR have a program for trapping and relocating them?
Sadly, people can sue you with no basis. Been on the receiving end of that one. Whether can win anything by...