The Australian magpie is helping biologists understand the evolution of intelligence, with a new study finding that birds which live in large groups are smarter than those who live in small ones.
The magpie (Cracticus tibicen), closely related to crows and ravens, is an iconic bird in the Australian landscape, loved and feared in equal measure.
The fear arises from the fact that nesting females aggressively swoop at animals – including, or perhaps especially, humans – often making contact and drawing blood. (During nesting season, legions of Australian children walk to school wearing ice-cream containers on their heads in a bid to thwart the attacks.)
The love comes from the fact that they are ubiquitous, readily identifiable, and possessed of a warbling song that has come to typify the sound of nature. In 2017, they were announced as Australia’s favourite bird, following a newspaper poll.
Also, of course, like most corvids, they seem rather clever. Now, research by zoologists at the University of Western Australia and the University of Exeter, UK, has confirmed that this is so – but their levels of intelligence are dependent on the size of the group they belong to.
To reach this conclusion, the Australian and English scientists examined 56 birds from 14 groups of wild magpies living in the suburbs of Western Australia’s capital city, Perth. The groups ranged between 12 and three individuals.
Each magpie – tested in isolation to avoid the risk of it getting help from its mates – was put through four tasks that taxed its cognitive abilities. These included finding food hidden in a transparent container, finding food hidden in different coloured containers, and a memory test involving finding hidden food.
Adult and juvenile birds were tested repeatedly and the results were clear. The birds that lived in larger groups were quicker to master the tasks than those that lived in smaller ones. The difference between quick-witted big group members and slower-witted little group members emerged very early in the birds’ lives.
In a paper published in the journal Nature, lead author Benjamin Ashton and his colleagues report that birds living in large groups “show increased cognitive performance”. Furthermore, this “general intelligence factor” is strongly linked to reproductive success in females.
Ashton suggests that the findings indicate the evolution of intelligence is influenced by pressures present in complex social groups.
“Our results suggest that the social environment plays a key role in the development of cognition,” he says.
“They also suggest a positive relationship between female cognitive performance and reproductive success indicating there is the potential for natural selection to act on cognition. Together, these results support the idea that the social environment plays an important role in cognitive evolution.”