How to keep birds away from terraces?
In the past, the birds were scared away with dry fires from an empty airgun, and it was known to be quite effective. How legitimate such method is today it cannot be said. Besides, it can be quite scary to other people.
This is an example of a remote-control deterrent. It means when birds come, you can scare them off using a remote control.
If there’s enough space, you could set up a bird scarer kite.
A very simple and effective method is to use bird tape. You can hang fluttering ribbons everywhere.
There’s also a manually-operated sonic bird scare, which you can use to keep away jackdaws or crows.