In the wild birds stay in touch with each other over long distances using what's known as a contact call. When a bird owner first gets their bird and gives it a name, they normally spend a great portion of the first few days and weeks with their new pet repeating the name over and over. As time goes by, the bird comes to recognize this name as their contact call to their person -- and they respond quite readily upon hearing it! Before making the decision to change your bird's name, ask yourself if the change is really worth it. Realize that it is likely to take weeks or even months for your bird to recognize this new "contact call." In the meantime, it may be difficult for you to get your bird's attention!
If you decide that you absolutely cannot live with your bird's current name, then you should spend a fair amount of time choosing the best name for your bird and making sure that it is a name that will "stick." Avoid names that you could possibly lose interest in over time, such as those associated with fads and trends. Parrots and other pet birds can live for a very long time, and it will not be fair to your feathered friend if you continue making him re-learn new contact calls over and over again. Once you have decided on a name and you are absolutely positive that it's the right one for your bird, then you can begin the process of teaching your pet his new name and contact call.
To begin, you will need to approach every interaction with your bird as a training session. Have a few tasty treats on hand, and work with your bird in short but frequent intervals, being careful to keep each session fun and positive. Call your bird's new name, and the immediately follow with your bird's old name. For example, if your bird's first name was "Sparky" and you are wanting to rename him "Sunny", then you will want too refer to him as "Sunny-Sparky." Upon hearing his first name, (Sparky, in this example) your bird will likely look toward you or respond in some other manner. As soon as he or she does this, present the bird with a treat. Repeat this process every time you call your bird by name, until you notice your feathered friend responding to you as the "new" name leaves your lips, and before you get a chance to say the old name. When you notice this happening, you can be assured that your bird is beginning to grasp his or her new name and contact call.
Since this is something that you'll need to practice quite frequently at first, it is a good idea to employ clicker training in your sessions, so that you don't have to give your bird so many treats. This is especially helpful for bird species that are prone to weight gain, or for individual birds with special dietary restrictions.