How can I tell the sex of my cockatiel it is all yellow with orange cheeks and red eyes?

The sex of your cockatiel cannot be accurately determined based solely on its coloration. While certain mutations can provide clues, sex determination in birds is usually done through genetic testing or observing the bird's behavior and physical characteristics. Male and female cockatiels can share similar color variations and markings. To accurately determine the sex of your cockatiel, it is best to consult with an experienced avian veterinarian or breeder who can physically examine the bird and perform appropriate tests.