BATTLING rising mouse populations is difficult because there is still much to be understood about the rodents' behaviour.
Over 500 people tuned into a recent GRDC-run mouse management online seminar, highlighting the mounting concern, especially down the east coast, at rising mouse populations.
However, while there are still unknowns, researchers said the core principles of reducing feed stock and targeted baiting remained the cornerstones of an effective mouse minimisation strategy.
Main speaker at the event, CSIRO mouse management specialist Steve Henry said predicting mouse behaviour was not straight forward.
"There are plenty of times I have an idea and I'm proved to be wrong. It is the difficulty in working with animals that have a brain and can behave unpredictably," Mr Henry said.
He reaffirmed the first thing growers needed to do was get out in the paddock and assess numbers.
However, he cautioned growers that it was not as simple as doing a quick check for burrows.
"On vertisol soils with big cracks you might not always get visible burrows. If that is the case you may need to use chew cards to get an accurate number," he said.
Mr Henry said farmers also had to be accurate when making burrow counts.
"An extra burrow you count as in your square metre is an extra thousand a hectare, it adds up."
On the baiting front, Mr Henry said while it could be tempting to combine mouse bait with other products, such as slug or snail bait, or even urea fertiliser, it was a definite no-no.
"If you were to put it into urea, as it is agitated with the urea in the spreader the zinc phosphide is being scraped off the surface of the grain," he said.
"Because you are scraping zinc phosphide off the grain you are increasing the chance of the mice getting a sublethal dose, causing aversion.
"The second problem is you are putting it out with urea, so there are two new things going into the paddock. If the urea tastes bad for mice they will not eat the new bait either but will go back to what they were eating before.
"Sheep are a great tool for this and if you've been lucky enough to get summer rain some of the seed from last year's crop should have germinated and you can spray it out," he said.
However, he said the issue was more difficult in summer cropping where the mice have the option of feed in the sorghum head.
"The best thing to do, although not perfect, is to continue baiting as generally the mice will prefer to feed along the ground where there is less danger," he said.