Efficient sexing of the globally vulnerable Saunders’s Gull (Saundersilarus saundersi) is urgently needed in the conservation research and practical management. The universal P2/P8 molecular sexing method has been proved to be invalid for this gull. Here, the improved molecular sexing procedure of Saunders’s Gull is described. The gene sequences of chromo-helicase-DNA binding protein (CHD)-Z and CHD-W were first obtained. Based on conserved regions inside the CHD-Z and CHD-W sequences, a sex-specific primer was designed. PCR products exhibited two bands (about 260 bp derived from CHD-ZW and 150 bp from CHD-W) for female gulls, while males exhibited only the 260 bp band. These findings suggest that the procedure represents a reliable method for sex identification of Saunders’s Gull. The shorter target fragments imply that non-destructive genetic samples might be used with our approach, which will facilitate further researches on the sex of this vulnerable species.

全球脆弱的桑德斯海鸥（Saundersilarus saundersi）的有效性别鉴定在自然保护研究和实际管理中迫切需要。通用的P2 / P8分子性别鉴定方法已被证明对该海鸥无效。在此，描述了桑德斯海鸥改进的分子性别鉴定方法。首先获得了染色体解旋酶-DNA结合蛋白（CHD）-Z和CHD-W的基因序列。基于CHD-Z和CHD-W序列内部的保守区，设计了性别特异性引物。对于雌性鸥，PCR产物显示两个条带（从CHD-ZW衍生出约260 bp，从CHD-W衍生出150 bp），而雄性仅展示260 bp。这些发现表明该程序代表了一种可靠的桑德斯海鸥性别鉴定方法。目标片段较短，意味着我们的方法可以使用非破坏性的遗传样本，