Depending on the environment there is a more or less clear defined breeding season. Eggs are normally of white color. Outside the breeding season parrots in general are very social birds which gather in flocks from small parties to thousands in number. This instinctive socialization soon made them pets in human history. Kept in captivity parrots are forced to take man as flock-social partner by instinct if there is no natural partner availibale.
Pair bonding is very strong.
Young parrots may choose their lifetime partners before maturity. In some of the species it is even possible that a bird will die after the loss of it's mate. The oldest fossile parrot has been found in Great Britain and is dated from the early Eocene - more than 60 million years ago. In human history we know of the first parrots brought to the ancient Greece. At the court of Artaxerxes II, the pysician Ctesias gave a description of the Plum-headed Parakeet and noticed it's ability to speak.