This morning I found the area around the two red rump pair cages looking like a crime scene. Blood was spattered all over the cage, the nearby walls and ceiling. Apparently something had caused the birds to have a night fright episode and they injured themselves flapping around in the dark despite the night lights. The bloodshed was an indirect result of something that happened a few weeks ago. Then, I just found lots of red rump wing feathers scattered around. The birds managed to drop all of their feathers on one or both wings. It is likely a small earthquake had disturbed them in the middle of the night. So now, instead of having one or two wing feathers growing back in as they should with a normal moult, they have a wingful or two of growing feathers. While they are growing in, these feathers have a blood supply and, if broken, can cause serious blood loss to the bird. The first aid recommendation for broken blood feathers is to pull out the feather in order to stop the bleeding.
I have no idea if the birds managed to do that to themselves or if the feathers just came out as a result of the panic in the cages. The evidence on the floor this morning shows that both of the hens lost at least three blood feathers last night, while the other red rumps lost one each. Meanwhile the other birds housed in adjacent cages showed no signs that they were bothered by the disturbance.