It holds peanut-size things, in particular those pink gubbins sold at my local flower shop. Starlings are big on them of course but also gold finches and so on. However, despite two robins being in our garden, I don't see them get the hang of it. They kind of hover sometimes around it but have trouble docking, or don't attempt it. Why is that?
They seem to shy away from the other birds which I find odd because they are the ones that come out and keep me company on a winter dig or leaf raking. I know that's said to be not out of affection but because they are bullies marking their territory but it seems odd they are like that with a human when other birds scatter at the sight of one, but they don't stomp around marking their territory when other, even fairly small birds, are out and about.
I do scatter seed on the ground so robins can get to it but I don't see them taking full advantage of that, either.