Apparently the woman who made it was just trying to find something to do with the metal bottlecaps she had from juice (or tea) bottles. She cut the triangle from a piece of scrap wood, nailed the caps to it and added a few dowels for perches. A quick paint job, a piece of string, and voila! I love it when people use scraps and create something totally useful!
I put this out for the first time this morning. I haven't had anything to put on the caps for food, but yesterday I purchased some peanut butter spread:
Normally I don't promote these things because they are pretty expensive. One could easily make up a batch for a fraction of the cost (it's just rendered beef suet, peanut butter, and I think cornmeal), but I was feeling lazy and just bought the tub. It's pretty soft (like peanut butter - imagine that) and spreads easily.
None of the birds flocked to it this morning before I left for work. I'll check it out when I get home tonight (it'll still be light!) and see if anyone was brave enough to approach this new and strange thing hanging in the tree.