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The researchers have established that chickens – just like people – have colour constancy. For birds, this means that they, in different environments and under different lighting conditions, recognise the colour of, for instance, berries and can thereby distinguish those that are ripe from those that are not. Without colour constancy, they would not be able to rely on their colour vision – they would simply see the berries in different colours as the light changed. They would certainly also not be able to recognise their own kind of species.