However, changes to farming operations could mean mouse number are higher more often, than they were decades ago.

CSIRO researcher Steve Henry monitors mouse numbers across Victoria and South Australia.

He will do in-paddock surveys for mice in Horsham next week and expects numbers will be low.

"In the Adelaide Plains this week we caught one mouse from 102 traps, which was very low," he said.

"So we are not expecting much in the Wimmera."

Mr Henry said mouse numbers fluctuated depending on seasonal conditions.

"We look at rainfall from late winter into spring, which provides a surrogate for food," he said.

"If we get good rainfall, we grow decent crops meaning that there is a lot of food in the system for mice.

"If we have a better than average crop this year, with some follow up rain in autumn and spring, then numbers will build up again.

"It's a double-edged sword - the factors that are good for crops are good for pests."

CSIRO researchers, in conjunction with the Grains Research and Development Corporation, have been looking into how mice adapt to changes in farming technology.

"All our understanding of mice has been based on conventional tillage systems," Mr Henry said.

"We had a big mouse plague in 2010 and we then received funding to start monitoring mice.

"Last year we got some funding to do more work on the way mice use zero and no-till cropping systems."

Mr Henry said zero and no-till systems might be more favourable to mice.

"The conventional thinking is that mice live on the edge of paddocks and moved into paddocks when conditions were favourable," he said.

"Farmers were often cultivating the ground meaning the conditions were hostile," he said.

"Now, with low levels of disturbance in paddocks, there is more shelter, food and stubble left in the system, so mice are living in paddocks, digging burrows and creating warrens.

"This might be a product of no-till and we need to get a handle on the way we use these systems and find ways to be more strategic."

Mr Henry said because of the change in farming systems, there have been higher numbers of mice in the region over the past few years.

"Better understanding of mouse ecology in zero and no-till cropping systems could lead to more strategic application of bait, potentially reducing the quantity of bait spread or increasing the effectiveness of bait by targeting high activity zones in paddocks," he said.

"The current approach to bait application is to spread bait on a broad scale across entire paddocks."

Researchers are also looking at mice food preferences and aversion to bait.

The Grains Research and Development Corporation's major mouse-related research, development and extension program has shown that mice prefer cereals over lentils.

Research has also found that background food significantly affected consumption of bait and strategic use of bait was more effective than frequent use of bait.

CSIRO researchers have been undertaking bait substrate trials to determine what is driving a perceived reduction in efficacy of zinc phosphide bait and testing potential new bait substrates that might be more attractive to mice.

Researchers are testing the willingness of mice to transition from one food to another and then determining whether mice will continue to eat that alternative food source once zinc phosphide bait has been applied.

Mr Henry said one experiment involved mice being held on a background food type (barley/lentils/wheat) for two weeks and then offered the choice of an alternative grain type for five nights.

"A clear key message from this work is that mice don't like lentils," he said.

"Results from trials have shown that mice have a clear preference for cereals over lentils which indicates lentils wouldn't be a good bait substrate for zinc phosphide."

Another experiment has aimed to determine the acceptance of different toxic bait substrates by mice when challenged against a different background food type.

Mice were kept on a background food type then offered an alternative of the three types of zinc phosphide-coated grain for three consecutive nights, as well as the background diet.

"Mice consumed toxic bait grains regardless of the bait substrate type, however, background food type significantly affected the number of toxic grains consumed," Mr Henry said.

"Mice established on a wheat background consumed fewer toxic bait grains than mice on a lentil or barley background diet. Mice on a barley background diet showed a slight preference for malt barley."

Mr Henry said an interesting outcome of this experiment was in relation to toxic bait aversion.

"Mice that ate a sub-lethal dose of toxin on the first night showed bait aversion - they stopped taking toxic grains on nights two and three.

"In all rodent populations, there will be some animals that are susceptible and some that are less susceptible to bait.

"If those less susceptible individuals consume zinc phosphide and don't die, then we end up with almost instant bait aversion."

The next phase of the research will examine the role of available alternative food on commercial zinc phosphide bait effectiveness.