Sheepdogs use simple rules to herd sheep
27 August 2014
Sheepdogs use just two simple rules to round up large herds of sheep, scientists have discovered.
The findings could lead to the development of robots that can gather and herd livestock, crowd control techniques, or new methods to clean up the environment.
For the first time, scientists used GPS technology to understand how sheepdogs do their jobs so well. Until now, they had no idea how the dogs manage to get so many unwilling sheep to move in the same direction.
NERC fellow Dr Andrew King of Swansea University fitted a flock of sheep and a sheepdog with backpacks containing extremely accurate GPS devices designed by colleagues at the Royal Veterinary College, London.
Daniel Strömbom of Uppsala University and colleagues then used data from these devices, together with computer simulations, to develop a mathematical shepherding model.
The team found that sheepdogs likely use just two simple rules: to collect the sheep when they're dispersed and drive them forward when they're aggregated. In the model, a single shepherd could herd a flock of more than 100 individuals using these two simple rules.
The research is published in the Journal of the Royal Society, Interface.
Andrew King explained:
"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. 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."
Daniel Strömbom said:
"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. Other models don't appear to be able to herd really big groups - as soon as the number of individuals gets above 50 you start needing multiple shepherds or sheepdogs."
Andrew King said:
"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."
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1. The research paper - external link - 'Solving the shepherding problem: heuristics for herding autonomous, interacting agents' by Daniel Strömbom, Richard P Mann, Alan M Wilson, Stephen Hailes, A Jennifer Morton, David JT Sumpter and Andrew J King is published in the Journal of the Royal Society, Interface, on 27 August 2014. Images of the sheep, backpacks and sheepdogs are available via Dropbox.
2. Andrew King's research project 'Does diversity deliver? How variation in individual knowledge and behavioural traits impact on the performance of animal groups' is available on NERC's Grants on the Web - external link -.
Press release: 20/14