Them Pesky sparrows!

After noticing something had been nibbling at my beetroot and chard leaves I turned to Google for some help to find out what it could be (what did we do before Google?!) With plenty of eggshell around them and no slime trail visible I didn't think it was slugs, so what could it be?...... Sparrows apparently, and with plenty of bird life around the place this does seem likely so project bird scaring has begun....