'Honeytrap' rats prove conservation solution

A Massey University researcher has a novel pest eradication suggestion, backed up by research: use rats to catch rats on conservation land. Photo / Thinkstock

Rats could be used to rid conservation land of rats, following novel pest eradication research by a Massey University biologist.

Researcher Idan Shapira, based at the Institute of Natural Sciences at Albany, has used live caged lab rats to attract and trap other wild Norway rats (Rattus norvegicus).

Mr Shapira said the rats cannot resist the power of same-species attraction, with the promise of sex or social interaction, rather than food as a lure.

Both the Department of Conservation and Auckland Council have already shown interest in using this method on protected conservation islands and reserves, as well as Auckland Zoo.

Mr Shapira has spent three years trialling the method for his doctoral study on the role of olfactory attraction in invasive rodents as a tool for conservation.

He believed the trapping technique could be well suited in conservation areas, where food often fails as bait due to the abundance of food available to pests in the habitat.

"A single rat can cause a lot of damage. If it's a pregnant female it's going to be even more of a concern," he said. "This is a practical tool for conservation management in situations where you have a few rats to get rid of in protected wilderness areas."

The trap has two compartments - one for the lure the rat and a separate one to trap the wild rat.

In field experiments in the Shakespear Regional Park north of Auckland, Matuku Reserve in the Waitakere Ranges and private land, Mr Shapiro caught eight rats using food bait and more than 50 using rats as a lure.

Auckland Zoo pest control coordinator Craig Knapp said the method has been a great success at the zoo, where rats were rejecting conventional baited traps because they find other food in the zoo. During a trial at the zoo, 11 rats were trapped using the lure rat.

"That's 11 rats we wouldn't have caught using traditional traps," he said.

Mr Knapp said rats can be a threat to smaller animals and birds and the zoo, and poison is inappropriate due to the risk of it being eaten by a zoo animal.

Mr Shapiro said he is in talks with Hamilton Zoo to use the method there.

He said it could also be potentially used to trap other pests such as stoats.