Sheep flock because they're selfish not stupid, scientists report. A study of how a flock of sheep moves to avoid a sheepdog has found the cloven hoofed animals head to safety in the centre of the flock, rather than scatter randomly.
The finding dispels the myth that sheep follow each other blindly when threatened.
Instead, the research supports the idea that an animal targeted as prey will band with its kind in the hope others will be eaten, a theory known as "selfish herd theory".
A team of British scientists attached GPS devices to the backs of 46 sheep and an Australian kelpie working dog on a South Australian farm and recorded the animal's movements every second over three herding sessions.
They found the sheep began to converge when the dog was 70 metres away.
Even as the flock as a whole moved, each sheep continuously competed to be as near the middle as possible.
The research leader and biologist, Andrew King, from the Royal Veterinary College of the University of London, said running towards the centre of the flock reduced a sheep's chances of being on the edge and picked off by a predator.
"Our experiments show that the sheep appear to be considering the position of multiple neighbours in order to move towards the [centre of the flock]," says King.
Many scientists support the "selfish herd theory", first proposed by the British evolutionary biologist Bill Hamilton, for why animals such as seals, crabs, and pigeons group together, but gathering data on the phenomena has been difficult.
A biologist from the University of Massachusetts, Theodore Stankowich, said it was difficult to measure 2D spatial information on large animals in the wild.
"They've taken advantage of a unique opportunity to work with the sheep to answer these types of questions in a controlled environment," Dr Stankowich, who was not involved in the study, said.
While the study used a sheepdog as the predator, sheep may have a different response to other animals, Dr King, whose findings are published in the journal Current Biology,said.
"[Dogs] could be a downgraded level of threat, because it's something the sheep have experienced before."
with ScienceNOW
