Watch for sparrows, they ate my beetroot, peas and spinach, but seem to have moved on now.

I lost all my first lot of beetroot and as there was no sign at all of slugs I assumed the birds did it.
But M. G. Suggested slugs were the problem so the next lot I set I put slug pellets round and for several mornings after there were lots of slug trails and dead slugs.

More likely to be slugs and snails than sparrows...