News about poles (shelf redux?)

The shelf may be gone but the pole remains. I found a blue and red ribbon and an orchid (a real one) on the pole a couple days ago. On Monday evening, while walking Smitty, we saw our neighbors, Jan and Ray, and they told us about something curious on a pole a block further. We walked together and there was a little note, the letters were curiously like worms and there were little birds heads, we looked up and there was a BIRD HOUSE!! Wild! A bit later, on our homeward bound walk, we saw our neighbor, Richard, and he said that there was a birdhouse on every pole, on both sides of the street, for a couple blocks. Now that is really wild! Did the shelf encourage this? I wonder about that, and I wonder, how long will these bird houses stay up on the poles?