Something eating the cauli leaves?

Is it on the leaf edges or more internal ?? Slugs ?? Caterpillars already on plants before netted ?? Mice ?? hedgehogs or pideons/pheasants??
R

Check all the leaves for caterpillars. The first year I covered mine with mesh but the transplants must have already had eggs on 'cos a few weeks later...there they were munching away under the netting when I had a look

Or slugs as already said........