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Blue tits and great tits can learn to avoid unpleasant foods without even tasting them. Seeing another bird’s disgusted response, even if it’s just on video, helps them avoid unpleasant prey by recognising their markings.
Liisa Hämäläinen at the University of Cambridge, and her colleagues studied this type of social learning in blue tits (Cyanistes caeruleus) and great tits (Parus major), which forage together.
Two groups of 24 birds, 12 blue tits and 12 great tits, were shown a video of either a blue tit or a great tit eating unpleasant “prey” – food soaked in a bitter solution and marked with a black square. The filmed birds reacted with disgust by wiping their beaks and shaking their heads.
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The birds who watched the videos were then introduced to unpleasant food and their normal, unaltered food to see if they had learned from the filmed birds. Another set of 12 blue tits and 12 great tits were presented with these food options without having watched the videos.
For both species, the birds who watched the video ate fewer unpleasant prey items than those who didn’t. Blue tits learned best by watching their own kind, but great tits learned equally well from observing either species.
While several birds have been shown to avoid certain prey by observing their own species, this has only been seen across species once before – between red-winged blackbirds (Agelaius phoeniceus) and common grackles (Quiscalus quiscula).
This is the first time blue tits have been shown to use social information to the same, and an even greater, extent as great tits. The researchers believe this could be because this study focused on risky food choices.
“The two species differ in size, and it is possible that great tits can cope better with chemical defences because they are larger than blue tits. The costs to consume potentially toxic food might therefore be higher for blue tits,” says Hämäläinen.
Predators learning from each other in this way could explain why certain prey animals develop conspicuous markings, despite these markings attracting attention. In places where multiple predators can learn from a single predation, this could make more conspicuous warning signals worth it.
Journal reference: Journal of Animal Ecology, DOI: 10.1111/1365-2656.13180
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