Hi,
The culprit is surley the dreaded Wood Pigeon.
I have had the problem from these little critters for a long time.
Best and only thing to do is cover with fleece or netting to stop the loss of valuable veggies from your plot.
The war on bugs and birds has started and there is not surrender by these specialists whoes only mission is to annoy the victim in this campaign,
:-X :-X :-X The plot owner.