How monitor lizards are being trained to avoid toxic toads

Australian scientists have devised an “innovative method of conservation” through feeding giant monitor lizards small cane toads so they won’t be killed by larger-sized amphibians. Researchers from the University of Sydney said they were able to teach free-ranging goannas in the Kimberley wilderness in north-western Australia to avoid eating the toxic toads about to invade the remote floodplain. The scientists offered small, non-lethal cane toads to the wild yellow-spotted monitors – which have experienced a 90 per cent plunge in population following toad invasions – with further trials confirming “just one or two toad meals were enough to convince a goanna not to eat another toad”.

After training, giant monitor lizards, known as goannas, survived when the toads arrived, whereas untrained lizards were immediately killed.

Lead researcher Georgia Ward-Fear

The goannas quickly learnt to avoid the adult cane toads in the wild after being exposed to the younger, smaller toads. Cane toads, an invasive species from Central and South America that were introduced to Australia in 1935, are so toxic they can kill predators that try to eat them and are continuing to spread across northern Australia at an estimated 40-60km (25-37 miles) a year. Scientists have said the spread of the cane toads – which an Australian university study showed numbered about 200 million on the island continent – was causing catastrophic population declines in predators.

Science goannas