Bad guys

I've been away from the PC all week and, despite the rain, trying to get out and about.
A couple of times, while birding, I've heard people talking about the decline of various songbirds, and blaming it on the crow family, and Magpies in particular.
It worries me, because all the recent research points to the fact that where Magpie numbers are high, so are songbird numbers, and vice versa. But, according to some (and these people all seemed to be pretty keen birdwatchers), the fact that corvids take eggs and young is wiping out some of our best-loved species.
Well, it's true that Magpies, Carrion and Hooded Crows and Jays do take eggs and nestlings at times, but because they are all native species, and have lived side by side with the songbirds since the year dot, such losses are effectively 'factored into' Nature's calculations. Large numbers of eggs and young do fall prey to predators, accidents, and so on, which is why most songbirds have two to three large broods a year. The Magpies, for their part, are highly omnivorous, so have no need to concentrate on a single food source.
The bit that worries me is that again it seems to be an example of humans trying to brush the damage that we do under the carpet. Pesticides, herbicides, and the rise of gardens consisting mainly of decking and gravel are far bigger reasons for the decline of songbirds, because they remove their main food sources - insects, seeds, and worms.
I'm also not so sure about the decline of all songbirds, anyway. Blackbirds seem to be doing phenomenally well (despite the fact that it's their nests you often see Magpies picking on). Even in a very small garden like mine, it's not uncommon to see three or four yanking worms out of the patchy lawn.