PNAS
When we hear a sound associated with a particular object, we are primed to see that object too. The ability to visualise something in this way was once thought to be unique to humans. But some birds seem to have that ability as well, a study has found.
When the Japanese tit hears a rattling alarm call like that of a snake, it responds as if a snake was nearby and reacts to objects that might be moving like a snake.
Scientists used a wooden stick to demonstrate the same talent in the Japanese tit, a songbird that produces particular alarm calls only when it encounters dangerous snakes.
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In a series of experiments, recordings of snake-specific calls were played while the birds approached a stick being moved in a serpentine fashion up a tree trunk or along the ground.
The birds responded as if threatened, but ignored the stick if other non-snake alarm calls were played or the stick’s movement was not snake-like enough.
On the lookout
“These birds do not respond to the calls in a uniform way, but appear to retrieve a snake image and then decide how to deal with the predator according to the circumstance,” says team leader Toshitaka Suzuki, from the Centre for Ecological Research at Kyoto University, Japan.
“With a snake’s image in mind, tits can efficiently search out a snake regardless of its spatial position.”
When they meet a real snake, Japanese tits typically go on the offensive, hovering over the reptile while spreading their wings and tail to deter it from attacking.
Faced with a snake-like moving stick, the birds reacted in the same way but their distraction behaviour was more limited.
“They may have realised that the stick was not a real snake once they got close enough,” says Suzuki.
Many animals, including monkeys and meerkats, have been shown to produce calls that warn of specific predators or share the discovery of particular kinds of food.
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Journal reference: PNAS, DOI: 10.1073/pnas.1718884115