There is only one type of leg band for imported parrots, which were issued by the USDA. All importation of wild caught parrots ended in the US in 1992. A legband on an imported bird is a rounded, steel open band. It will either have three letters and three numbers, or it will say USDA with three numbers. If your bird’s leg band only has the number 83 on it, then this was put on by a breeder. It is probably a flat metal band. The 83 could indicate the year, although a lot of breeders use leg bands until they run out, instead of buying new ones each year. While most breeders do use closed leg bands, not all of them do. Some put the band on too late, in which case they have to use an open band. Some breeders use the USDA style rounded leg bands for large birds like cockatoos, because cockatoos have been known to crush the other type of leg band. Open bands should be removed by an avian vet when possible because they pose a risk to the bird by getting caught on a toy or cage bars.
Depending on the species of cockatoo, you may be able to determine the gender visually. Otherwise, and inexpensive DNA test is the way to go. Many of the white species of cockatoo can be visually sexed. The female will have red eyes when she is mature and the male will have very dark brown eyes. However this is not 100% accurate.
Both a male or female cockatoo will adopt a substitute for an egg. Regardless of sex, this should not be encouraged and the object of their affection need to be removed when the bird is distracted. Otherwise it may trigger unwanted hormonal behavior such as aggression from a male or Chronic egg laying for a female.
There is no such thing as egg bonding but you are probably referring to egg binding. Egg binding can happen to a female bird when she is trying to lay eggs. Many things can cause her to not be able to pass the egg and the bird will die without veterinary help.
Thank you for asking Lafeber,