Cockatiels birds which are also known as a weird bird, or quarrion and they are both cuddly and bright. If you have a cockatiel in your home, then you can hear their chirps and whistles. Cockatiel birds are generally available in grey color, but they are available in various colors like pearl, white-faced, pearl, lutino, variegated and many other color varieties. An average Cockatiel's size is 11 to 14 inches long, and a well-cared cockatiel can live up to 25 years.