- Sep 28
- 3 min read

Taste Aversion to Save Crocodiles

By Eleanor Gil Sep 25 2024

If someone has ever had food poisoning or rotten food and never again went near that certain food, they have experienced taste aversion—a learned response, usually long-term repulsion, after encountering toxic food. Scientists have poisoned crocodiles by purposefully inducing this same phenomenon in them, all because of one tiny creature twice the size of a teacup. The cane toad—a slimy creature with dark, brown warts running across its skin—has become one of the worst invasive species in the world, according to the Global Invasive Species Database, with the potential to kill any animal it comes into contact with. Cane toads are native to South and Central America, but have had an especially devastating impact after being introduced to other parts of the world, such as in Australia. They were initially brought to Australia by the government in 1935 at the request of sugar cane plantation owners to control pest beetles. Now, these creatures have turned into pests themselves, spreading uncontrolled in the millions across the country as well as in other affected areas, such as Florida, Hawaii, the Philippines and the Caribbean Islands.

The Australian crocodile has become one of the most vulnerable native species because their natural prey includes native frogs, which they confuse with the non-native cane toad. The cane toad secretes a highly toxic, milky-white venom called bufotoxin through their skin when they sense a threat. However, unaware crocodiles consume them whole, promptly after which the crocodile may experience lethal symptoms such as rapid heartbeat, seizures and paralysis which often lead to death through massive cardiac arrest.

Freshwater crocodiles populations have been severely affected in northern Australia; some populations have plummeted by 70%. This threatens local ecosystems: the crocodile is a keystone species, as it is the apex predator that keeps the growth of all other species below in check. According to the scientific journal Nature, when such a crucial species becomes weak, the rest of the food web may crumble in a ripple effect, leading to a decrease in biodiversity.

Australian scientists are working with Indigenous rangers and wildlife management to develop a previously known but relatively recent solution to save crocodiles: taste aversion. Scientists are attempting to induce anti-frog eating behavior and repulsion through food poisoning. They condition the crocodiles by feeding them dead cane toads that have been modified to induce food poisoning instead of death. The dead cane toads still exude the same smell and taste of their live counterparts, but with most of the lethal toxins removed by the scientists and replaced with a nausea-eliciting compound. They want the crocodiles to irreversibly associate the nausea with cane toads and learn to avoid real ones in the future. According to NPR, two years later, when the scientists returned, they discovered that they had managed to cut down mortality rates by 95% when they compared the region they intervened in with a control area.

“It is crucial to support the ecosystem and ensure it doesn’t collapse, and scientists may have to intervene when necessary. Conditioning through taste aversion is non-invasive and has the potential to solve the problem without impacting other species,” Senior Vira Patil said.

This taste aversion strategy is not new—for example, it had been used two decades ago to condition black bears to stop eating military rations. However, after a year, the association with the black bears decreased, and they returned to eating the rations, which may imply that the association may also decrease with the crocodiles and cane toads. Therefore, according to NPR, it is likely that scientists will need to continue these trials every few years. Taste aversion is currently the only reliable method of intervention and thus the only viable option for conservation, and trying to eliminate all toads has been impossible so far, as reported by The Guardian.

“Taste aversion as a strategy demonstrates the ability of humans to intervene in a poDDsitive manner and protect the environment they had initially threatened. Also, taste aversion is scarily effective—I remember eating a spoiled mango when I was a kid and throwing up, and from then on, I never dared touch mangoes or any other fruit again,” Junior Chris Chen said.

From a conservational lens, this intervention may be applied to save other crucial species across the world in similar situations. As the intervention has the power to leave a direct impact within the brain, the results are quick, and quick is what is needed right now to help save the natural world.

About the Contributors

Eleanor Gil is a junior at Leland High and the page editor for School News and Feature School for The Charger Account. She loves to cultivate a quiet, eclectic joy derived from various interests and hobbies and above all, learning.