Just picked up on this and having the same issue. I use a small seed songbird mix and they threw everything out. I then mixed in a quantity of black sunflower seeds. They ate those and threw the rest out. I'm thinking of using another feeder with just sunflower seeds in to see if they prefer that. Anyone with any experience of doing this or other thoughts. I live near a stream and I'm now inviting the rats in which I'm keen to put a stop to.
Hi Gordon, absolutely recommend feeding ‘straights’ ie. just sunflower hearts instead of mixes, as otherwise each bird sifts through the mix to find what they like, chucking the rest on the ground. Even with this, goldfinches and sparrows still tend to be messy and so I’ve attached trays just an inch below the caged feeder (the same width as the cage so big birds can’t perch), and then the robins and tits jump in the tray. I occasionally scoop some of the food back into the tube if it’s clean (which it always has been so far) but if it was wet/pooey I’d chuck it of course. Very very little ends up on the ground with this set-up, just about enough for my two dunnocks.
Finches are notoriously picky. I live in Quebec, Canada and it's no different with the finches here. Don't know if it's available in the UK but I use a blend of finely graded (chopped) sunflower chips and nyjer seed in a tube finch feeder.The feeder has has ports with 3 tear-drop shaped holes that allow the fine chips to pass freely without spilling out. My experience is that American Goldfinches tend to lose their taste for nyjer seed in the winter months (when temperatures here can go down below -30°C) and they prefer the chips. The House Finches, Purple Finches and Pine Siskins are less fussy. Having some nyjer seed in the mix also helps to prevent the chips from clumping and maintain flow. Some nyjer seed gets wasted but the chips are consumed efficiently. - the only thing discarded is what what remains of the flaky pellicle attached to the chips. Actually I posted a review of the tube feeder I use on YouTube. I'm unable to post the link here (gets rejected) but a search for "Wilderness Fred's 15" Finch Feeder : In-use Evaluation" will find it on my channel (NowThen Media). It's an unbiased review - I have no affiliation with the seller. Just to add, using a food processor or spice/nut grinder to break sunflower hearts/kernels into smaller fragments will not produce the desired results. I've tried it. you'll end up with mostly powder. Hope that helps.