I've got three cockatiels and one of them, Hershey 12-13 years old, started vomiting. The first time it happened was last November. We took her to a vet and they said it was hormonal and gave some suggestions on how to get her to stop. The behavior decreased but never went away. We took her to a different vet in January who said basically the same thing. Sometimes I think I've got it fixed and she'll go a couple weeks to a month without doing it. Yet she always ends up doing it again. The most effective thing so far has been limiting her seed input (but the other birds aren't huge fans of this as it means they get less too) but nothing has worked 100 percent. This is the only hormonal behavior she does and everything else is fairly normal. Also, any suggestions on how to clean her when she does? It gets all over her face and I always end up taking a couple feathers too when I wipe it off.