I've mentioned the local rice dryer several times. There are actually several in the area -- this one is called "Midway Rice Dryer". It has a shoot (actually a sort of pipe) that sticks out the side for the "exhaust" which is mostly rice hulls and some broken pieces. The blackbirds, of course, love the broken bits. So do the mice, and we sometimes see Hawks here.
This first picture is interesting. The black birds with the vertical stripes are Red-winged black birds. The black birds with brown heads are Brown-headed Cow Birds. I think the female bird among the RWBB's the other day was a female Brown-headed cow bird.