Horses have mobile ears, which help them to communicate in ways that humans can't, a new study says.
According to researchers at the University of Sussex, horses are sensitive to not only facial expressions of other horses, but also to their eye and ear movements. This keen sense of observation helps these animals remain cautious of predators.
The study also challenges the idea that animals with eyes on the side of their faces can't keep a track of other animals' eye movements.
"Our study is the first to examine a potential cue to attention that humans do not have: the ears," Jennifer Wathan of the University of Sussex said in a news release. "Previous work investigating communication of attention in animals has focused on cues that humans use: body orientation, head orientation, and eye gaze; no one else had gone beyond that."
"However, we found that in horses their ear position was also a crucial visual signal that other horses respond to. In fact, horses need to see the detailed facial features of both eyes and ears before they use another horse's head direction to guide them," she explained.
For the study, researchers set up a behavioral experiment, described in the journal Current Biology. During the tests, life-size images of horses were used to manipulate behavior of test horses. The study team found that horses would follow the gaze of the horse in the image to locate a food source. When the team covered a specific part of the horses, say eyes or ears, the test animals could not follow the directions and chose a random food source.
Horses, like many other animals, can rotate their ears through 180 degrees. The researchers said that humans have used a limited perspective while studying communication in horses and so have missed out on an important factor that determines social behavior in these animals, according to BBC.
"It seems there's something in the visual cues - from both the eyes and the ears - that are really important," Wathan told BBC News. "Horses have quite rich social lives and relationships with other horses, so they're a good species to look at this in."