Hi Amber,
The problem is the Quaker isn’t being bad. The behavior is perfectly normal, but of course as a pet, it is unwanted behavior. The only way you could expect the behavior to change would be to separate the birds. Adult parrots naturally look for a mate, and once they have one, they do not have physical interaction with other birds in the flock. Other birds are rivals and would only be allowed to get so close before being chased away. Your birds might actually be two females. In captivity, same sex birds will bond. You can have more than one pet bird, but once you let your birds share a cage, you risk losing them as pets. I feel like the one that is territorial is probably the one that laid the eggs. If the other one is also female, this would explain why she is still letting you pet her. I think if you had a male, he would be more bonded with the female and neither bird would be tame now. But this is just a guess based on the one bird remaining tame.
You have to decide if you want to let these birds stay together, in which case the biting will only get worse. Or separate them and the one that is biting may eventually return to being tame. You have inadvertently put them in a very confusing situation. The bird that is still tame, is still bonded to you as well as with the other bird. But this means the bird’s affections are torn, and at some point the tame bird will probably choose the other bird over you. I know this all sounds very confusing, but now you can imagine how the birds feel! LOL If you do separate them, when taming or training, keep in mind that parrots do not learn from punishment or negative reinforcement. All bad or unwanted behavior should be ignored and good or desirable behavior should be rewarded with treats and attention. Always remember that their behavior is instinctive, so they have to learn from you what is ok and what isn’t.
As for the egg laying, you don’t want the bird to lay eggs again if you can help it. It’s very hard on a female to form eggs and lay them. It’s something they only do one time a year in the wild. But in captivity, they can get stuck in an egg laying cycle and end up needing hormone treatment from a Vet in order to stop. Unless you plan to give up both birds as pets and breed them, then you can make some changes to discourage egg laying. Separating the birds can help. Limit their light to 8-10 hours per day, by covering the cages early each evening. Do not give either bird a box, nest, bird hut or tent or anything it can use as a nest. When you pet your birds, you should limit contact to the head and neck. When you pet a bird on the body, you are sending the message that you are the mate. It will trigger their hormones and can cause egg laying & aggression in a female and aggression in a male. When the birds are out, don’t let them get in dark, cozy places.
Thank you for asking Lafeber,
Brenda