Scientists discover how to put elephants off their favourite foods

Elephants can be tricked into avoiding their favourite meals by making them smell like a dish they find distasteful.

University of Sydney researchers have shown it is possible to shield plants from hungry mammals using the technique - which could prove a boon for farmers looking to keep hungry beasts away from their crops without harming them.

Findings from the study in Nature Ecology & Evolution show tree seedlings planted next to a solution mimicking the smell of avoided plants were 20 times less likely to be eaten by animals.

"This is equivalent to the seedlings being surrounded by actual plants that are unpalatable to the herbivore; tricking the animals so they take much longer to find and feed on them," said PhD student Patrick Finnerty, the study's lead author from the School of Life and Environmental Sciences Behavioural Ecology and Conservation Lab.

"Herbivores cause significant damage to valuable plants in ecological and economically sensitive areas worldwide, but killing the animals to protect the plants can be unethical," he said. "So, we created artificial odours that mimicked the smell of plant species they naturally avoid, and this gently nudged problematic herbivores away from areas we didn't want them to be."

The experiment was initially conducted on a swamp wallaby in Ku-ring-gai Chase National Park in Sydney. The researchers selected an unpalatable shrub in the citrus family, Boronia pinnata, and a palatable canopy species, Eucalyptus punctata, to test the concept.

As part of his doctoral research, Finnerty then tested the method successfully with African elephants, but that fieldwork does not form part of this research paper.

Previous attempts to use repellent substances, such as chilli oil or motor oil, to control animal consumption of plants have inherent limitations, Mr Finnerty added.

"By contrast, by mimicking the smell of plants herbivore naturally encounter, and avoid in day-to-day foraging, our approach works with the natural motivators of these animals, with herbivores less likely to habituate to these smells."