I have quite a few magpies and other corvids around my home which Im unable to shoot due to location. So over the last few years Ive monitered the song bird population and it is thriving. I have many song birds nesting succesfully in my garden. I think a major problem is places suitable for nests. If you research various species and look at there nesting requirements you will reaslise the are few places they can nest. Some birds won't nest above 4 ft above ground and so its not trees they require. Some trees such as hazle dont provide much oportunity for nesting.
I know we all like to shoot but sometimes I feel people create an argument for shooting to justify the sport. There are times I,d love to shoot but know the prey is far from a pest in that environment, and may be helping the local ecosystem. eg There are few rabbits around me, and I leave them for the birds of prey who are doing great in the area. Although Id love top be shooting them, I know there is a very sparse number around here.
I your really concerned about song birds etc. plant a few buxxus and let it grow naturally. You will have lots of small birds nesting there. Ive got some plants here I'm happy to give to anyone who can collect them.
BTW I find I can't watch anything with Kate Humble in it, every word seems to annoy me :o