Feeding garden birds

I just want to say that I followed your advice, Paul, and bought 20kg of sunflower hearts off eBay. The birds absolutely love them!! I can't believe the number of goldfinches that have been on the feeder since I put those in - we have a flock around pretty much all day now, all trying to get on the sunflower hearts and only going back to the njyer seeds if there isn't enough room for them to get on the sunflower hearts! Bluetits and great tits are loving them, too. I had always bought the normal sort of mixed seeds before, and the only birds that really liked those were the sparrows. I was wondering how I would ever get through 20kg of these sunflower hearts, but the rate they are eating them now I think it won't be a problem. Should still last the winter though I hope.