Sorry to hear about the failed crop. Are the flowers getting pollinated by bees? Some raspberry plant varieties only bear fruit on last year's canes so too much pruning is not good. If the new growth is too lush and green, the balance of nutrient could be off with too much nitrogen. It seams that they thrive on neglect. I like to mulch them with wood chips. There is something about rotting wood that they really like. I don't seem to have much of a bird problem. My problem is when the hornets find them they will pick them clean in short order.