Zebras bob their heads to attract attention and initiate social interactions such as grooming or moving together. This may be one of the few documented examples of signals that animals use to coordinate their behaviour.
The capacity for multiple animals to focus on shared goals or objects in their environment, known as joint attention, is key to cooperation in humans, but it has rarely been investigated in wild animals.
at Princeton University noticed some plains zebras (Equus quagga) making repeated up-and-down motions of the head and neck, and wondered if it was a signal to other zebras.
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To investigate further, Hex and her colleague studied a herd of 112 zebras at Ol Pejeta Conservancy in Kenya from July to September 2021. They noted each time one bobbed its head and how the others reacted. They also noted whenever one or more zebras began to move, as head-bobs often occurred in these situations.
In total, they spotted 164 head-bobs in 290 hours of observations. Statistical analysis of the data strongly suggested that zebras bobbed their heads intentionally when other zebras were around. The gesture elicited a response around 70 per cent of the time, and all the responses were friendly. The receiver would often head-bob back, almost as though giving an answer.
鈥淚f the signaller head-bobbed and travelled, the recipient would also travel with them. Or they would both end up grazing in close proximity or grooming each other,鈥� says Hex. Whenever head-bobs were ignored, on a third of occasions the zebra involved would make the same movement again within the next 30 minutes.
鈥淭he importance of finding this signal is that until now, we have mainly looked for joint attention in primates and domestic animals. But now we are finding suggestions that the ability to use signals to coordinate joint behaviour may be more widely spread than originally thought,鈥� says Hex. 鈥淭his has great implications for the evolution of complex social cognition, and highlights the importance of investigating diverse species.鈥�
at the University of Pisa in Italy says a similar head-bobbing signal is seen in spotted hyenas, which cubs use to initiate playful interactions with the members of the clan. It is also reminiscent of yawning in lions, which leads to more yawning in observers, she says.
Animal Behaviour
