When seedlings begin to emerge lightly sprinkle them with white flour... I use a kitchen sifter. The stark white of the flour, an uncommon sight in nature, startles the birds and rabbits. So much so that they will avoid the seedlings, giving them a chance to grow up with their heads intact. Reapply as necessary.
This theory was tested here using my darling Peacock, Rajah, who is the worst offender since garden snacking is his favorite hobby. He was surprised, cocked his head to the side and one-eyed the white dusting.... then he slowly moved along, disallowing he was nervous. It works!
* Rajah showing off~