Keep in mind that large birds are typically long-lived species. Parrots can actually live in excess of fifty years if they are well cared for. Do not let the pet store clerk talk you into a large species of bird if you are not prepared to provide decades of care to it, no matter how much fun it might sound to own one.
It is possible to tell the sex of a parakeet from the band of flesh that grows across its nostrils, called a cere. A male parakeet will have a smooth bluish or purple cere, while the cere on a female will be tan or brown and will be rough in appearance. Only parakeets at or approaching physical maturity will be differentiated in this manner.