One minute, a herd of goats is wandering around casually through the thicket of grass. Next time, their long ears quiver and their large golden eyes stare as they turn purposefully away, picking up speed when they appear to be running intently toward a specific destination. They exhibit a behavior that scientists have long monitored in herding, gathering, and schooling of animals from baboons to fish.
It almost looks like the goats have cast their votes and decided together which way to go.
How creatures in the animal kingdom come to decisions together is a topic of perpetual importance. In some species individuals do weigh in. Members of meerkat troops call and sneeze African wild dogs before the group moves, and they don’t hit the road until enough individuals have had their say.
It has even been said that African buffaloes vote with their movements, with animals pointing themselves in the direction they want to go and the herd choosing the average of all their directions.
However, it is difficult for a human observer to distinguish between forays guided by silent voices and forays where animals copy whatever their closest fellow countrymen do, as schooling fish do. Using collars equipped with GPS and other sensors, biologists looked at a small herd of Namibian goats to see if their behavior suggested one tactic or the other. In an article published Wednesday in the journal Royal Society Open Science, they report that the goats don’t seem to vote.
If animals decide in advance which way to go, there must be a delay between when the majority orient themselves in the direction of travel and when they leave, said Andrew King, who studies animal behavior at Swansea University in Wales and an author. is. of the new paper. But it can be difficult for researchers to pinpoint the moments that matter.
“If you just sat in the field with a notebook, you couldn’t do it because you don’t know when they are leaving,” he said.
He and his colleagues have developed collars with GPS devices, as well as accelerometers and magnetometers that track which way animals are facing, when they start to move together and where they eventually end up. They put the collars on 16 domesticated goats in the Tsaobis Nature Park in Namibia and collected data as they roamed for 10 days. With this information, they could go back to just before the group left a particular location and determine when they turned to their destination.
If there was a vote, the goats would orient themselves before the movement began. A majority can look at the direction they are ultimately going, or the direction can be an average of their positions. In any situation, there would be a delay before the goats acted on the decision.
Instead, the researchers saw that the goats did not start looking at their destination until they left. That meant a goat would start moving, the nearest neighbors would turn to follow it, and their closest neighbors would do the same, a behavior the researchers call copying. That meant that the orientation of the goats for an outing did not predict which way they would go.
The researchers also built a computer model to simulate what the goat movement would look like if they voted instead of copying. Some virtual herds of goats were programmed to copy their neighbors, while others voted with their views. The researchers found that what the goats were doing in real life was much more like the copycat herds, suggesting that the animals don’t have to do anything other than mimic their companions to move around as a group.
Behavior that stems from very simple rules can be surprisingly complex. Goats may not have discussions – at least not what scientists saw in this study – but that doesn’t mean their ways of moving together aren’t flexible or helpful. If more research confirms that they move by copying, it could indicate that mimicking neighbors can improve herd survival and other good outcomes more often than not.
Dr. King said that if many unrelated species use this decision-making process instead of voting, “it probably means that this is a useful, adaptive way to make collective decisions.”