Sexual dimorphism in the cane toad Bufo marinus : a quantitative comparison of visual inspection methods for sexing individuals

A study was conducted to determine whether simple morphological characteristics could be used to rapidly determine the sex of cane toads. We found that four characteristics reliably allowed rapid assessment of sex: skin texture on the dorsal surface, skin colour on the dorsal surface, the presence of a creamy-coloured stripe along the dorsal margin and the presence of vocal sac openings. These criteria were tested by an assessment of use by both experienced and novice operators and were shown to be reliable for sexing cane toads that were large enough to assess morphological characteristics reliably (individuals with a snout-vent length exceeding 50 mm). Of the four techniques, the presence of vocal sac openings proved to be the most reliable. Such techniques may be used for a number of purposes, and are particularly useful during conservation projects that attempt to eradicate or reduce the effects of this invasive alien species on local ecosystems.