A study of wild Australian birds found that an invidiual's gonads and appearance may not align with its genetic or chromosonal sex determination. The phenomenon is more common than expected and "may challenge the reliability of traditional sexing methods" reliant on morphology.

The ability to unequivocally identify the sex and reproductive status of individuals is crucial across many fields of study. Recent evidence indicates that avian sex determination is more flexible than once believed, with sex-reversed individuals identified in domestic bird populations—that is, individuals exhibiting gonadal and morphological traits of one sex while possessing the chromosomal make-up of the opposite sex. The presence of these individuals can challenge the reliability of traditional sexing methods t

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