Maybe find a feeder with flexible perches that tip the bigger birds (and squirrels) off when they raid.

hi i have the circular type feeder balls the ones with a wire mesh circle around them large birds squirrels etc cannot get the food cheers

I suffered with crows, pigeons and magpies and was told to hang moth balls nearby. I was very sceptical but thought it worth a try and it worked for me. I thought the whole garden would reek of mothballs but I put them away from the path and eveything was fine. I also changed bird food and bought one with no corn in it.

Thanks all, I will certainly try the mothballs and see if they work. We have ordered some of the above feeders but they feed off the spilled seed on the ground as well (buggers)