This is perhaps the most common and certainly the safest method. Basically, it requires that an owner slowly wean their bird off of seed and on to pellets and other "stuff." The process usually followed is that an owner offer a bowl mixed initially with 3/4 seeds and 1/4 pellets. This is just so the bird gets used to seeing the new food and associating it with something to eat in the food bowl. Some birds may even pick at the pellets (although some may throw them out of the bowl, as well). This mixture should go for about 1 week. Next, you should mix the seeds and new foods half and half. Again, maintain this ratio for about 1 week. Next, give your bird 3/4 pellets and 1/4 seeds for about 1 week. Finally, fill your bird's dish with entirely pellets. Over the month of the conversion, give your bird a second food bowl full of dark green fruits and veggies, beans, cooked brown rice, pasta, grains, etc. You bird may not touch these foods for a long time. Eventually, however, most birds become curious and may start to "play" with the new soft foods. This play often leads to eating when the bird learns how good the strange-looking new foods taste.
Advantages to this Method: The slow conversion method is very safe. It offers your bird time to get accustomed to seeing the new foods before it is required to eat it. We need to remember that birds are prey animals. As such, they are very suspicious of unfamiliar things. Parrots may need to observe things like toys and foods before they actually use them. This method allows for this. Also, since foods like processed pellet squares and macaroni pasta are not something birds instinctively see as food, this method allows them time to visualize these things with a food that they know, seed. Hopefully, they will start to associate the new foods with the joy of eating they derive from seeds. Also, with a slow conversion method there is little chance of rapid weight loss if your bird refuses to eat anything but seed, because seed is always available, although in slowly decreasing quantities.
The Problem: This method is not perfect. If it were, it would be the only one we needed to know. First off, it takes a very long time. Second, because birds are very smart, they can also be very stubborn. There are those birds, especially cockatiels and parakeets, that will eat around all the new foods, picking out only the seeds. Expecting that more seeds will be forthcoming, they will eat only seeds even as the stock dwindles day by day. It is almost as if they expect that if there are any seeds at all, it is not even worth trying to find sustenance in any other food. For bird such as these, the key truly is, again patience. Most birds can be converted, it is usually simply a matter of whose will is stronger, the bird or the owner.