Budgies are a highly gregarious species, and breed best when you have three or more pairs within sight and sound of one another. I personally recommend colony breeding these guys. They are usually not aggressive and will coexist peacefully with similar species, particularly other Aussie keets. Some people even keep them with zebra and society finches. Not only will colony breeding increase your chances for success with budgies, but it will allow you to observe them as a flock, a key to learning about bird behavior.