I feed a small flock of Jackdaws on my front lawn (about a dozen), the numbers have not varied much over the years which is something I find surprising when I take into account the food availability, so just what is the limiting factor, i'm not sure but could it be nest sites or territorial disputes. I don't think trapping or shooting is a factor although it's quite possible larsen trapping is carried out in the wider countryside. I seem to remember Lew mentioning he had made a study of Jackdaws in his youth (many years past) and I will ask him about his conclusions. A few woodies and a couple of rooks also put in an occassional appearance but once again not excessive numbers. Many folk take exception to feeding these type of birds but I love their company and as long as I make sure my small bird feeding requirements are protected i'm happy to share my food store with them , after all Jackdaws feel hunger too.
They are often rather greedy and quarrelsome individuals, and they remind me of another species - oh yes! it's mankind.