Hello - My is Chris Jenkins, and I am one of the Supervisors with Steve Martin’s Natural Encounters, Inc. I’d be happy to offer some advice that I hope can be helpful to you regarding this challenge you’re experiencing with your bird.
Any time a new human enters the life of a companion parrot, it is not at all unusual to see a change in the bird’s behavior as a result. What you are referring to as jealousy are a series of behaviors that are your bird’s way of reacting to a new form of stimuli in her environment. If we strip away the “jealous” label and instead look just at specific, observable behaviors that reliably occur under specific circumstances, we can begin to look at specific strategies that we can employ to help make life a little easier and more positive for you, your family, and your bird.
Let’s look at the behavior of biting. All behaviors are driven by their consequences; if your bird is biting, it is doing so either to get something that it wants or to get away from something that it finds aversive. I’d look at the specific situations under which you see this biting/lunging occurring. Is she physically near the baby at the time? Are you bringing her close to the baby at the time, or vice versa? In either of these situations, if your bird is uncomfortable, she may have learned that biting is the only way to get the situation to stop.
What I think you should focus on is looking at how you can set the stage for and reinforce the specific behaviors that you want to see more of. Paint a picture of what you want the situation to look like; if you can clearly describe what you want to see your bird do in the presence of the baby, then you can form a plan for how to go about training that. Start with small steps if that is what the bird is comfortable with, and make sure to find ways to back up the bird’s good behavior with things that she finds reinforcing (treats, attention, toys, etc). With time and repetition, your bird will begin to associate the presence of your child with these positive experiences, and very likely will even look forward to being able to spend time around the baby.
I hope some of these suggestions are helpful to you. Best of luck to you and your bird!