-- First, isn't this the most disgusting habit you've ever seen?
OK, let me clarify the difference between vomiting and regurgitation, which is really a pretty big difference:
A bird that bobs its head up and down in a sort of pumping motion, beak open and then a purposeful delivery of partially digested food is regurgitating. This is something they would do to feed offspring or a mate. It’s done by some birds to objects they are particularly fond of, especially if they’re in a breeding season. It might also be done when the bird is nervous or trying to ‘please’ you.
Regurgitating can be a symptom of crop infection or other problems, but generally it’s a threat because it can lead to malnourishment. If your bird is giving up too much of the food they should be digesting for their own nutrition, the result can be pretty serious.
Vomiting is more of a head ‘flicking’ event. The bird will often seem uneasy, pacing or uncomfortable and although the head bobbing might be similar to the regurgitation action, it’s usually more of a shaking and the end result is a very splattered, sticky substance that may or may not include food.
If possible, collect a sample of this substance to bring to the vet with you.
When there’s a blood showing in the vomitus it may indicate esophageal or proventricular ulcers (http://www.multiscope.com/hotspot/pdd.htm) .
The vet will take a look into your bird’s mouth for other symptoms and I’d ask for a swab culture if the vet isn’t going to do one anyway. A good exam will also check for any growths or tumors.
Vomiting is a more serious symptom and seeing a vet as soon as possible is important. There are far too many possible diseases to outline here, but as in any case of illness, getting it evaluated, diagnosed and treated right away is often the best outcome at the lowest cost.
The top causes of vomiting in domestic birds are (gram-negative) bacteria, something that may increase to a troublesome point after the bird is stressed somehow. Stress can involve changes in their environment, being frightened, having their sleep hours reduced or other changes in schedules or even a difference in food.
The other possible causes are contamination of food or water by fecal matter. Be sure there are no perches above food/water bowls which could allow this to happen without you noticing until after the bird has ingested it.
Candida (also increased after a stressor) infection or Trichomonas are also causes that should be explored by your vet. When these are all ruled out, the search for a cause can get pretty complicated.
If you’re dealing with regurgitation, as hard as it might be for you to do, remove the object of your bird’s affection and begin to modify the bird’s light and dark hours to help curb this behavior.
By changing the cage around, switching up the food and water dishes, taking out familiar toys and adding new ones, you alter the possible triggers. Change the location of perches, or the types, but always keep in mind that the highest perch where the bird will spend most of their standing time should never be a coarse or grooming perch which can cause foot and leg problems. Those perches are excellent options in a cage, just not for long time standing or sleeping.
Take a look here for more about sleep, sleep cages, open perches and lots more www.4AnimalCare.org/birds
While I've never been 100% successful at stopping the regurgitation, in most of the birds that came to me doing it regularly I've gotten it reduced to isolated incidents, usually done when the bird is unsure of a particular situation or trying too hard to impress someone new or different in their vicinity.
Just never yell at him for doing something perfectly natural; however, the moment you see it beginning, calmly walk over and quietly remove the object he's aiming for with the explaination "That's not necessary" (I'll use anything except the word "no" which I think too many birds hear too often)