MISUNDERSTANDING the movement of snails is costing farmers time and money in the paddock.
Northern & Yorke NRM regional landcare facilitator Michael Richards has been studying its activity on the southern Yorke Peninsula since February 2013, in conjunction with SARDI and federal government funding.
It is one of the few research projects to monitor snails this close.
At the recent SPAA precision ag expo at Wallaroo, Mr Richards said there were many misconceptions about snail behaviour and triggers that influenced such behaviour.
"Many farmers question: I've done such a good kill, why have I still got snails in my crop?" he said.
"We knew they moved at night when it was cooler, but we didn't really know the extent of what was happening between daylight and dusk.
"There was also much conjecture about how early snails became active and the level of activity over the autumn period, so we decided to start a trial."
Mr Richards said they also began the study to gain more region-specific and snail-type data.
The technology used comprised two time-lapse cameras in a paddock.
One camera was placed on the edge of the paddock with the second about 60 metres in-crop.
Mr Richards said some farmers did not understand the need for the second camera as many believed snails, particularly conicals, did not migrate far from the edge.
"But that was one thing we noticed in the trial - from early March up until June, there were minimal snails observed by the second camera, only on the first camera on the edge of the paddock," he said.
"Come June 1, the camera showed both conical and round snails had moved inwards into the crop."
Snails had reinfested a clean paddock to a distance of 70m from the edge by early June in 2014.
Previous studies had looked into triggers for directional movement, such as weather, wind and cover height, but none were conclusive.
Mr Richards said they were yet to pinpoint reasons for the migration as feed sources were plentiful on the edge.
"I think it's (migration) just a survival thing - it happens every year, and in many species," he said.
He said the study also highlighted that snail movement was dictated by humidity.
"They don't move much in the day, but at 3am it's a different story," Mr Richards said.
"We initially thought it to be at least 90 per cent relatively humidity before the snails would become active.
"However, by the end of March, snails were active at about 80pc to 85pc humidity."
Mr Richards said they then came up with the idea of comparing observations of snail activity with Bureau of Meteorology weather forecasters to see if they could identify a correlation.
"What we found was the snails became active at lower humidity when there were jumps in barometric pressure in the mid-March period," he said.
"They were anticipating cooler nights with moisture for breeding and survival of juveniles. It was almost like they were predicting the weather!"
High barometric pressure in mid to late March also coincided with the start of mating.
Mr Richards said the study also looked into different starts to the season at mating time, with February 2013 on the YP extremely dry and February 2014 extremely wet.
But the timing was relatively similar despite the dramatic difference in climate - March 27 in 2013 and March 18 in 2014.
"Egg laying can begin as early as 14 days after mating, but egg laying is dependent on greater than 12 millimetres of rainfall wetting the soil to a depth of about 30-40mm," he said.