Those are some nasty animals spoiling your crops! It's sometimes hard to find a friendly way of removing them.

As an amateur gardener that just started a small vegetable garden in his own backyard I also have small problems.
I had planted broccoli and the leaves were showing holes after a few weeks.
I suspected snails to nibble on the leaves, so I put pieces of broken egg shell and residu from grinded coffee beans around them....
Until I found out that the culprit was even smaller than I suspected:

I found this little guy on one of the leaves one day. Very tiny, but since it was just another shade of green than the leaves, I managed to spot him.

Maybe you could send me some of your birds @riverflows so they can remove all my caterpillars :D