Here's something interesting (well I think it's interesting):
The Crows that visit my garden mostly come for the nuts in shells, but they take the odd scrap of bread occasionally. Their behaviour is fairly predictable. Some pick out 2 or 3 nuts in shells that fit nicely in their beaks, others break the shells and take the nuts (thus getting more nuts per visit). All of them fly onto the fence to check the nuts are secure in their beak, then they fly off.
For the last week a couple of Crows have favoured bread, in fact they've taken every available piece. I've taken the time to break the bread into small pieces, only for the Crows to collect it all together in a big lump and wedge it in their beaks and fly off with it. I assume that the bread (which is wholemeal) is for their chicks; I'm pretty sure they are feeding young.
The really interesting behaviour was this morning:
One of the Crows broke open a few nuts in shells, took the whole nuts out, broke some into small pieces, and flew onto the fence ready to fly off with the nuts in it's crop/beak. At that moment I threw bread out. The Crow (which is used to me, so didn't fly off) spat out all of the nuts, flew down and collected all the bread I just threw out, and flew off with it stuffed in it's beak. So the Crow could have flown off with, or eaten, the nuts, but instead wasted them in favour of the bread. I assume that the bread was preferred because of the bulk, and a thick slice of bread will keep a chick happier for longer than a couple of nuts. Whatever the reason, I think this is a good example of how intelligent Corvids are. I would imagine quite a lot of thought must have gone into the simple act of spitting out a few nuts and taking the bread instead.