Invited reply: Rates of avian sex reversal: a response to Balogh <i>et al.</i>

We thank Balogh et al. for their comments on our recent article on sex reversal in free-living birds.Rigorous scrutiny is essential when reporting phenomena that challenge established assumptions, and we welcome the opportunity to clarify our approach and interpretation.They rightly highlight the critical importance of rigorous methodology when identifying rare phenomena like sex reversal, where the potential for misclassification must be carefully considered.The alternative explanations they propose, such as genotyping errors, sample contamination or ambiguous gonad morphology, are indeed possible sources of discordance in any study of this nature.The central question, however, is not whether these errors can occur, but whether they provide the most plausible explanation for the consistent pattern of discordances we observed across multiple species.While independent validation of discordant individuals would strengthen inference, the scope and resources of the present study limited additional analyses.We therefore interpret our findings as preliminary evidence warranting targeted follow-up rather than definitive confirmation of sex reversal in individual cases.Our study aimed to address a significant knowledge gap: the occurrence of sex reversal in wild birds.While sex reversal is well documented in other vertebrate taxa [1], its prevalence in birds has remained largely unexplored.We explicitly framed our conclusions as preliminary in order to stimulate further research rather than assert universality.Our intention was not to claim that sex reversal is common across all avian species, but to report observed mismatches and highlight the need for deeper investigation.To do this, our study employed the widely accepted and practical standard for large-scale genotypic sexing in birds: PCR amplification of a single sex-linked marker.This method, while not infallible, is the foundation upon which thousands of ecological and evolutionary studies rely.Balogh et al. correctly note that single-marker PCR assays can misclassify genotypic sex under certain conditions [2].Indeed, we acknowledge this limitation and stated it in our original paper [3].Balogh et al. suggest that every discordant case requires validation with additional sex-linked markers or cytogenetic tests.While theoretically ideal, this is often logistically and financially prohibitive.Worldwide, single-locus PCR remains the standard method for avian sexing in field-based studies due to its reliability, cost-effectiveness and logistical feasibility [4].Importantly, the markers we used have been shown repeatedly to work well across species, including those in our study (e.g.[5]).Although new techniques are being described, their use has not yet been validated across bird families globally (including specifically in Australia), something we encourage as a next step [6].Our replication of PCR from the same DNA