Pearling in cockatiels is linked to gender-- after maturity, 99% of male pearl cockatiels will lose their beautiful speckles. If this bird is over a year old, it's a 99% sure a hen!
Most cockatiels are sexually dimorphic once they are mature. With so many mutations these days, 'bright cheeks and face' is NOT a reliable way to sex them, however other clues are! Spots under the primary feathers (the flight feathers on the wing-- only visible when the wing is open), and barring on the vent feathers (feathers that cover the vent-- barring, not spotting) are two great clues to a hen, as well.
Most cockatiels are sexually dimorphic once they are mature. With so many mutations these days, 'bright cheeks and face' is NOT a reliable way to sex them, however other clues are! Spots under the primary feathers (the flight feathers on the wing-- only visible when the wing is open), and barring on the vent feathers (feathers that cover the vent-- barring, not spotting) are two great clues to a hen, as well.