Sheepdogs use just two simple rules to round up large herds of sheep, according to scientists, a finding that could aid the development of herding robots.
Researchers led by Dr Andrew King, of Swansea University, fitted a flock of sheep and a sheepdog with backpacks containing highly accurate GPS devices designed by colleagues at the Royal Veterinary College in London.
Daniel Strömbom of Uppsala University and colleagues then used data from these devices, together with computer simulations, to develop a mathematical shepherding model built on the two simple rules that seemed to guide the sheep dogs behaviour: collect the sheep when they are dispersed and drive them forward when they are aggregated.
“At every time step in the model, the dog decides if the herd is cohesive enough or not. If not cohesive, it will make it cohesive, but if it’s already cohesive the dog will push the herd towards the target,” said Strömbom.
According to Strömbom other models struggle as soon as the number of individuals gets above 50 and they start to need multiple shepherds or sheepdogs, but the model devised by his team could herd a flock of more than 100 individuals using these two simple rules during computer simulations.
The research, published in the Journal of the Royal Society Interface, is the first time scientists have used GPS technology to understand the tactics of sheepdogs.
“If you watch sheepdogs rounding up sheep, the dog weaves back and forth behind the flock in exactly the way that we see in the model,” said King, who is a fellow of the Natural Environment Research Council.
“We had to think about what the dog could see to develop our model. It basically sees white, fluffy things in front of it. If the dog sees gaps between the sheep, or the gaps are getting bigger, the dog needs to bring them together.”
The findings could have applications in host of technological fields, according to King.
“There are numerous applications for this knowledge, such as crowd control, cleaning up the environment, herding of livestock, keeping animals away from sensitive areas, and collecting or guiding groups of exploring robots,” he said.