The research offers a new way to control the impact of predators such as rats, foxes and cats without employing lethal force; a method that is considered to be a ‘blunt tool’ when it comes to reducing predator numbers.
“Predators, like all foragers, must make constant decisions about what information to pursue and what information to ignore in their search for food,” said the paper’s co-authors, Professor Peter Banks and Dr Catherine Price from the School of Life and Environmental Sciences.
Making good decisions requires animals to have accurate information about food, which means they are vulnerable to ‘fake news’.
Based on the principles of decision-making theory, the ‘fake news’ solution – developed by Professor Banks and Dr Price – works by assuming predators will give up or move on from areas that offer little reward. It also predicts they will stop searching for prey that are too hard to find when other food is available.
Working in the riverbeds of the Mackenzie Basin on New Zealand’s South Island, scientists tested the response of cats, ferrets and hedgehogs to false odour cues at nesting sites for three endangered shorebird species.
“To undermine the predators’ tactics, we put out ‘fake news’ about birds’ nests before the birds arrived to lay their eggs. This was of a mix of bird odours typical of a nest, designed to trick predators into thinking the scent would not lead to food,” Professor Banks said.
“Predators were initially attracted to the odours, but within days they lost interest in the odour and stopped visiting it,” Dr Price said. “When the birds arrived to nest, the predators weren’t interested in them.”
The nest survival statistics were striking for all the nesting bird species. Compared with sites where the ‘fake news’ hadn’t been deployed, odour treatments resulted in a 1.7-fold increase in chick production over 25-35 days – and doubled or tripled the odds of successful hatching.
The scientists predict that for certain species, such as the banded dotterel, this intervention could result in a 127 percent increase in population size in 25 years of annual odour treatment.
“The experiment shows we could significantly reduce predation rates and produce population-level benefits for vulnerable prey species, without directly interfering with animals,” Dr Grant Norbury, lead researcher from Manaaki Whenua – Landcare Research, said.
“Our approach cost no more to run than a traditional lethal control program, and delivered comparable conservation benefits,” Dr Banks and Dr Price said.
We hope this work will encourage others to consider this approach to reduce impacts where lethal control options are too difficult or ineffective.