I thought it was illegal, well here in Andalusia, it is common place and the locals do not seem to be the slightest bit concerned who sees them.
Today is our first full day in Zahora on the Spanish coast, it is south of Cadiz and is where the Battle of Trafalgar took place. Not in Zahora but out to sea from Zahora, the coast juts out and there is a light house called Faro Trafalgar.
They have decoys which seem to be Goldfinches in little cages, they set about 6 of these out and then put up some nets. When some birds are decoyed into the area they pull a string and the nets fall down and catch the birds.
The men then run to the nets and check what they have caught. I did see some fly up and away, whether these were not wanted or whether they escaped I do not know. I also saw one chap stamping on something, whether that was a bird or maybe he was securing the pegs that hold the nets I do not know.
What I do know is that they were very busy and did not seem at all concerned about me or my camera. It would be so easy to restrict this, all the local police would need to do is drive past every so often and when they found any one doing this to just confiscate their nets and cages. No need to prosecute, simply by removing their equipment it would make it very difficult to replace as I am sure the cost would be quite substantial.
I was directed to a good article about this practice and it is worth a read. Click http://www.birdguides.com/webzine/article.asp?a=1542