I used to tie those throw away aluminum pie pans to a tall stake in my vegetable gardens at the farm. When the sun reflects off the pie pans, it scares the birds away.
I also had a giant 6' long blow-up snake I put in the garden...and a bunch of those big rubber snakes (they cost about a buck each). Sometimes I'd be in the garden and see one of my fake snakes and it would freak me out for just a second...especially when I stepped on one.
But, it did help keep the birds from eating stuff.