What a great idea! Scrap Yarn Bird Feeder is an easy way to use up your scraps and help the birds build their nests after winter. When yarn is just too small to use for a knit or crochet project, don't throw it away; let the birds use the yarn instead.
Great idea for a unique bird feeder: Use a old bundt pan. How to hang it you ask? Just get some twine and wrap around a tennis ball, put underneath pan and bring two ends of twine up through top and tie around tree or whatever place you find to hang it.
Log Bird Feeder - 23 DIY Birdfeeders That Will Fill Your Garden With Birds (my note: I haven't looked at all of these, but at least one is a terrible idea. The window birdfeeder -- birds could fly into the glass and hurt themselves.