In a moment, a herd of goats romps about and casually rummages in the shaggy grass. The next time her long ears twitch and her large golden eyes stare as they purposefully run away. They pick up speed while seemingly attentive to a specific destination. They exhibit behavior that scientists have long observed in herding, herding, and training animals from baboons to fish.
It almost looks as if the goats have cast their votes and decided together which way to go.
How creatures in the animal kingdom come together to a decision is a subject of constant interest. In some species, individuals weigh themselves. Meerkat troop members call and African wild dogs sneeze before the group moves and they will not leave until enough individuals have spoken.
It has even been suggested that African buffaloes vote in concert with their movements, with animals pointing out the path they want to go and the herd choosing the intersection of all their directions.
However, it is difficult for a human observer to tell the difference between forays through silent voting and those in which animals copy whatever their closest compatriots do, as school fish do. With collars fitted with GPS and other sensors, biologists observed a small herd of Namibian goats to see if their behavior suggested one tactic or another. In an article published Wednesday in the Royal Society Open Science magazine, they report that the goats don’t seem to be voting.
If animals decide in advance which route to take, there should be a delay in when the majority will orient themselves in the direction of travel and when to head out, said Andrew King, who studies animal behavior at Swansea University in Wales and the author is the new paper. However, it can be difficult for researchers to pinpoint the crucial moments.
“If you were just sitting in the field with a notebook, you couldn’t do it because you didn’t know when to go,” he said.
He and his colleagues have developed collars that contain GPS devices as well as accelerometers and magnetometers that track which direction animals are moving, when they are moving together, and where they will eventually land. They put the collars on 16 domesticated goats in the Tsaobis Nature Park in Namibia and collected data while traveling for 10 days. With this information, they could trace back to just before the group left a certain location and determine when they turned towards their destination.
If there were to be a vote, the goats would orientate themselves before starting the movement. A majority could face the direction they are ultimately moving, or the direction could be an average of their positions. In any situation, there would be a delay before the goats responded to the decision.
Instead, the researchers saw that the goats did not face their destination until the moment they left. That meant that a goat would start moving, its closest neighbors would turn to follow, and their closest neighbors would do the same, behavior the researchers call copying. This meant that the orientation of the goats before a foray did not predict which direction they were going.
The researchers also built a computer model to simulate what the movement of the goats would look like if they were to vote or just copy. Some virtual herds of goats were programmed to copy their neighbors, while others voted with their positions. The researchers found that what the goats did in real life looked a lot more like the copycat herds, suggesting that the animals didn’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 way of moving together isn’t flexible or useful. If more research confirms that copying makes them move, it could suggest that mimicking neighbors can often improve herd survival, as well as other good outcomes.
Dr. King said that if many unrelated species use this decision-making process instead of voting, “it likely means that it is a useful, adaptable method for making collective decisions.”