London: The same colour vision that allows us to distinguish between a ripe and unripe fruit or recognise our own species is also found in chickens, new research has found. Just like humans, birds also have colour constancy which helps them in recognising different colours under different light conditions, the study said. 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. To test if birds have similar colour constancy, researchers from Lund University kept chickens in an environment with white light and were given access to containers marked in three different colours - red, yellow and orange. Only by selecting the orange container would the birds receive food. The researchers then studied which container the chickens selected when the light in the room was switched to different shades of red. The results showed that the chickens continued to select the orange container. The research was published in the scientific journal Proceedings of the Royal Society B. "We studied many different lighting conditions to find out how big the changes in light could be without the chickens losing their colour constancy,” said Peter Olsson from Lund University in Sweden. The researchers also calculated how big the changes in light are inside the chicken's eyes using a mathematical model.