First, feed rats a varied diet ...

Feeding rats a varied diet early in life could help in implementing effective control programs.

New research from the NSW Department of Primary Industries (DPI) suggests that changing rats' eating habits before introducing food baits could make the baits more effective.

DPI Vertebrate Pest Unit leader, Dr Glen Saunders, said rats are notoriously difficult to control and that much research to date emphasised changing the type or dose of poison or food bait, rathen than altering the rats' behaviour.

A new study, published in the May issue of the journal Applied Animal Behaviour Science, examined the effects of rats' diets on a phenomenon known as conditioned taste aversion.

More commonly known as "bait shyness", conditioned taste aversion occurs when an animal associated the taste of a food with illness, and then chooses to avoid consuming that food.

"All rodents are neophobic, which means they have a dread or hatred of novelty."

Dr Saunders said rats on a single food diet who feel ill after eating one bad experience with a new food, develop a more persistent aversion to that particular food.

"Meanwhile, juvenile wild rats exposed to a variety of novel foods will be less suspicious."

The study compared rats raised on laboratory animal pellets with rats fed a variety of seven foods including raisins, peanuts, maize, quail eggs and maggots.

Dr Saunders said the study suggested that rats that had a varied diet early in life, and for whom new foods had been a positive experience, appear more willing to associate all novel foods with safety.

He said that the finding may be of particular benefit for environmental control programs, for instance in protecting eggs from rat predation.

"The effectiveness of food baits might be increaded if rats are given more different types of food before being baited.

"This opens the door to using alternative or perhaps less poisons", Dr Saunders said.

NSW DPI invests resources into researching practical methods for controlling a range of pest animals and this project was undertaken in collaboration with scientists in the United Kingdom, where a great deal of rodent research is undertaken.

The research was funded by the Pest Animal Cooperative Research Centre (now Invasive Animals CRC).