Australian magpies that live in flocks are more intelligent than their more solitary counterparts. We don't want to draw any conclusions from this about urban and rural humans, but the findings support ideas about how we got so smart in the first place.
Australian magpies are unrelated to European magpies but do have a similar color scheme. Recently named Australia's bird of the year in a hard-fought contest, the birds are members of the passerine order. They are actually one of the few native Australian birds to flourish since European colonization, coping well with urbanization, even if their relationship with cyclists can get nasty around nesting season. The Western Australian subspecies differs from its relatives over east, however, in that they live in groups of up to 17, rather than in pairs.
Dr Amanda Ridley of the University of Western Australia told IFLScience that magpies represented the perfect bird for testing a long-standing, but still controversial, theory; that living in groups makes animals more intelligent. Known as the “social intelligence hypothesis”, the idea runs that negotiating relationships requires a lot of brain power, and this spills over to other applications. Ridley said; “To test this you need animals with stable territories so you can find them, that spend a lot of time on the ground and that are habituated to humans.” Not only do the Australian magpies do all of these, but their complex songs have long hinted at their intelligence.
Ridley and colleagues gave four intelligence tests to magpies living around Perth in populations that ranged from three to 12 birds, publishing in Nature. "We showed that individuals living in larger groups in the wild show elevated cognitive performance, which in turn is linked to increased reproductive success,” co-author Dr Alex Thornton of the University of Exeter said in a statement. "Repeated testing of juveniles at different ages showed that the link between group size and intelligence emerged in early life." However, when the young birds were first tested group size had no effect, contradicting the theory that birds with genes for higher intelligence form larger flocks.
Ridley said the study also demonstrated the evolutionary benefits of intelligence, with smarter female magpies producing more offspring. She told IFLScience one of the future lines of research the team is interested in is establishing why this is the case. “Are intelligent females better at avoiding predators, do they get better food, or avoid conflict with others in the group?” she said. “Or are they better at seeking help from others in the flock?”
Although magpie fathers do some of the work of raising the young, the researchers were not able to test whether males also gain a benefit from being smart, because of uncertainty about paternity. Ridley told IFLScience Australian magpies have the highest rate of extra-pair mating of any known species where pair bonds are formed. Only with extensive genetic testing of all the magpies within a wide vicinity, not just in the flocks the team studied, will it be possible to see whether smarter males get a similar benefit.
Eventually, such further research could put a lot of detail into the social intelligence hypothesis. The proponents of this theory think it explains how humans achieved brain development to the extent that we have. Ridley told IFLScience most attempts to confirm the hypothesis have involved comparing the brain size of social species with close solitary relatives. However, she noted, brain size does not correlate perfectly with intelligence, and can also be affected by other ecological influences.
Within-species studies have usually been done in captivity, with all the problems that involves, so this paper breaks new ground.
To measure magpie intelligence the authors had them learn to associate a particular color with food, and remember where food had been hidden. Hardest of all was when food was placed inside a transparent cylinder with open ends. Birds needed to show self-discipline to use the openings, rather than repeatedly trying to peck at the sides, a test many humans we know would fail.
Given the additional offspring that intelligent female magpies produce, it might be expected that magpies will simply keep on getting smarter until only the lack of thumbs prevents them from putting roadsters in space. Ridley said she thinks it is an interesting question whether there is a ceiling on the rise of magpie intelligence, and if not, what is preventing the social birds becoming ever brainer?