I keep a little, undyed cusspot at my desk at the office and stuff every tiny shred of thread in it. After several months it was pretty packed so I took it out onto the grounds and left little bits here and there on the shrubs.
Last evening this was the only one I could find. The birds nests in the vicinity all have Art!
There is Art for us too, sadly unattributed and one or two woodpeckers have had at it.