Every few years perfect conditions emerge for an explosion in mice numbers, and this year is shaping up to be one of them.
In 2016 yields were record-breaking but due to the amount of grain left on the ground, mice are now a real threat to winter cereal crops due to be sown soon, particularly canola.
Agronomist Barry Haskins, AgGrow Agronomy, Yoogali, said mice numbers were significant in the Griffith district and in the western Riverina.
“It’s not a widespread problem but the numbers are significant where we are finding them. Many of my clients sowing canola are baiting for them now,” Mr Haskins said.
Interestingly, producers were seeing more burrows than mice in the paddock.
“In 2011 this was the same case and the mice came up the surface when the weather got colder.”
In his experience, sowing canola at five to seven centimetres deep adequately protected the seed.
Landmark agronomist Mark Golder, Cootamundra, said mice populations were not yet at a problematic level while further north Peter Watt, Elders Cowra, said there no more mice than usual.
CSIRO research officer Steve Henry has been up close and personal with rodents for years. Every year he does three field trips from Colleambally to the Mallee and Wimmera in Victoria, the Adelaide plains and finally the Yorke Peninsula trapping, collecting, recording and re-trapping mice on the same 60 farms.
“Due to the high yielding barley crops in the Mallee and Wimmera in 2016, much of the grain lodged and fell to the ground, providing a smorgasbord for the resident mice,” Mr Henry said.
“Mice are an eruptive species, meaning the population can shift from being a low density population of five per hectare to more than 100/ha in the space of days. It is the speed of population growth that catches people out, but when you understand the life-cycle of mice, rapid action to halt the spread can be very effective.”
Mice start breeding at the age of six weeks, have litters between six and 12 young and are in season the moment they give birth. With an average life span of two years, this equates to a female mouse being capable of producing 300 young in her lifetime.
“Sometimes, we need to think like a mouse to anticipate what they may do next.”
Birchip Copping Group’s communications manager Ciara Cullen said if there are more than 80 mice a hectare farmers should start baiting.
“It is cheaper to put out bait a few times than re-sow,” Ms Cullen said.
- Report any sightings to www.feralscan.org.au/