How's this for a nifty idea, passed on to my mother by an acquaintance who has to travel away a lot. She couldn't bear the idea of her garden birds going hungry, and didn't have anyone else that she could rely on, so she bought a downpipe (the sort that comes from guttering -hope I got the technical term right), and two of the curly bits that come at each end. She fills this up with bird food. One of the curly bits goes on the top to keep the rain out, the other curly bit goes on the bottom with the food spilling out. She then props the whole thing up at a slight angle. Must take an enormous amount of food, but it keeps her birds happy while she's away.