now that my large bag of niger seed is nearly done, I intend to start feeding sunflower hearts, but do I need a special feeder or will the old niger seed feeder do for sunflower hearts as well?
I mix sunflower hearts and niger seed together but you'd better check the size of the holes in your feeder. You will have a heck of a lot of frustrated birds if they can't get the hearts out of the holes:-)
I feed the niger seed for our variety of finches in the summer months here in the western U.S., however I feed sunflower hearts in the winter for the chickadees and nuthatches (and others). The niger feeder won't work for the sunflower seeds... in fact the best feeder I've found for the sunflowers is a chalet looking device (like this: http://www.birdfeeders.com/store/wild-bird-feeders/50153?utm_source=google&utm_medium=cse&CAWELAID=1564985120&cagpspn=pla&gclid=COy8-InI3LQCFQioPAodbzsASg ... about 12 inches long, 10 inches wide and maybe 8 inches tall... it has a removable lid that makes filling it easy.
I mix the sunflower hearts about 3:1 with regular black oil sunflower seeds. The black seeds are often kicked overboard by the birds and they make good feed for the ground feeding Slate Races and Redpolls plus a variety of ground feeding woodpeckers (plus all the sparrows)... Besides the sunflower hearts are more expensive.
I would advise using purpose built feeders for different seed types, especially where the seed drops down into a hopper
Of course you could always scatter some loose seed, if you have a surplus, for ground feeders and those that don't take to feeders
Please bare in mind that it may take some while for birds to adapt to a new food offered