London, Feb 8 : Living in a large social group makes magpies more intelligent, finds a new study emphasising that social environment plays an important role in cognitive evolution.
Magpies are considered as one of the most intelligent animals in the world, and one of the only non-mammal species who are able to recognise themselves in a mirror test.
The findings revealed that wild Australian magpies from larger groups showed an "elevated cognitive performance", when tested for their memory, problem-solving and ability to control behaviour.
Females who are more intelligent are likely to have more offspring, indicating there is the potential for natural selection to act on cognition.
The demands of living in complex social groups may have played a role in the evolution of intelligence, the researchers suggested.
"We showed that individuals living in larger groups in the wild show elevated cognitive performance, which in turn is linked to increased reproductive success," said Alex Thornton, of the Centre for Ecology and Conservation from the University of Exeter in Cornwall.
For the study, reported in the journal Nature, the team tested 14 wild groups of Australian magpies' cognitive ability using four tasks, including one in which they had to learn to associate a particular colour with the presence of food, and a memory task where food was hidden in the same place many times.
There was also a test of self-control, in which magpies had to stop themselves from pecking directly at the food through the transparent barrier and instead had to go round to the sides of the tube to get the food.
"The challenges of living in complex social groups have long been thought to drive cognitive evolution," said Ben Ashton, from the University of Western Australia.
"However, our results suggest that the social environment plays a key role in the development of cognition," he added.