Female-female Amplexus and Extremely Female-skewed Operational Sex Ratio in the Toad Duttaphrynus cyphosus During Breeding Seasons

We report four cases of female–female amplexus in Duttaphrynus cyphosus observed over a five-year period (2019–2025) in Xiaayu Town, Chayu County, Tibet, China. The phenomenon occurred under conditions of an extremely female-biased operational sex ratio (OSR, 15–20 females per male), largely caused by local harvesting of males for consumption and trade. While female–female amplexus was rare compared to typical male–female pairs, its occurrence under such skewed demographic conditions suggests a potential link between sex ratio imbalance and atypical reproductive behaviors. These findings contribute to the limited literature on same-sex amplexus in amphibians.