all you can do is use some form of bird scarer. cds on strings flashing in the breeze will work.

but why do you want to discourage the birds? They will repay you by eating lots of caterpillars etc throughtout the year.

If there is damage to the grass they may be eating leatherjacket grubs. A good thing too as they eat and kill the grass. I know Starlings do a lot of damage digging up these grubs.

All birds having a wonderful time digging on my lawn since scarifying it last week. I don't care what they do as I love watching them.