Sex Reversal in Wild Birds Linked to Pollution: What We Know (and Don’t)
A new peer-reviewed study has just documented sex reversal in 3–6% of several common Australian birds , where genetic sex (ZZ/ZW) doesn’t match reproductive anatomy. The mechanism isn’t confirmed, but endocrine-disrupting chemicals (EDCs) and other environmental stressors are prime suspects, consistent with a broader body of work showing pollutants can masculinize/feminize birds, skew sex ratios, alter hormones and behavior, and depress reproduction . Blue-winged kookaburra What “sex reversal” means in birds Birds use genetic sex determination (males ZZ, females ZW). “Sex reversal” here means the phenotypic (gonads, reproductive tract) and genetic sexes don’t match, for example, a genetically female (ZW) bird with testicular tissue, or the reverse. Unlike fish and reptiles (where temperature can switch sex during development), in birds this has been thought rare . The new Australian dataset shows it can occur at non-trivial frequencies in the wild. The new evidence from Austr...