Overview

• A peer-reviewed paper in Biology Letters examined post-mortem gonads and DNA of 496 wild birds from five common species treated at southeast Queensland wildlife hospitals.
• Researchers identified sex-chromosome and phenotype mismatches in roughly 4.8% of individuals, with 92% of reversals involving ZW females developing male organs and one ZZ kookaburra showing recent egg production.
• Standard DNA-based and visual sexing methods misclassified up to 6% of birds, raising worries over skewed population models and captive-breeding program errors.
• Authors caution that undetected sex-reversed birds could distort sex ratios, disrupt mate pairing and undermine reproductive success in conservation efforts.
• Environmental triggers such as endocrine-disrupting chemicals or stress are proposed causes, but definitive drivers and population-level impacts await controlled, representative follow-up studies.