December 5, 2021

I, Science

The science magazine of Imperial College

There's growing evidence that some could be much cleverer than previously thought ...


If we call somebody a birdbrain, we’re normally implying they’re a little lacking in the old grey matter. But scientists are discovering that our feathered friends aren’t quite as dim as the old adage might suggest.

A study published in PLOS this year claims that crows have reasoning ability to rival a 7-year-old. The researchers, led by Sarah Jelbert from the University of Auckland, used the Aesop’s Fable paradigm to test New Caledonian crows’ understanding of causal relations. In this test, scientists observed as the crows dropped stones into a water-filled tube to raise the water level, thus bringing an out-of-reach reward up to an obtainable height. The crows did fail two of the harder tasks presented to them, but still demonstrated an understanding of water displacement that is only usually observed in people once they reach the age of five to seven.

But this isn’t the first time that birds have shown themselves to be brainier than once suspected.

For years the urban carrion crows of Japan were teased by their walnut-rich surroundings – a nutritious food supply tantalizingly protected by a hard, impenetrable shell. That was until passers-by noticed that the crows seemed to be purposefully dropping the nuts into the path of passing automobiles. Once the nuts had cracked beneath the cars’ tyres, the crows would dive down to collect their spoils. They even learned to selectively drop the nuts onto pedestrian crossings, so they could safely collect their cracked snack while the traffic paused. The BBC captured this smart behavior on film in their Life of Birds series (watch here). The direct scientific study of this behavior is, however, a little lacking; one study found no significant evidence for the crows’ selective road-dropping, claiming birds were just as likely to drop their nuts on the road as anywhere else. However, a 2001 study by Nihei & Higuchi published in Psychologica Folia found that crows did demonstrate a significant preference for roads as their selected nut-dropping site.

Clever crows aren’t the only brainy birds though. In 2010 Tom Flowers published a study in the Proceedings of the Royal Society showing that the mischievous South African fork-tailed drongo bird uses deceptive mimic calls to steal food from troops of meerkats. First, the sneaky drongo gains the meerkats’ trust by emitting an alarm call when a dangerous eagle flies by. Once the danger has passed, the meerkats reemerge from their burrows and continue feeding. The drongo then sounds a second warning, sending the meerkats scurrying off again to safety. Only this time, there is no eagle. This leaves the drongo free to scavenge the meerkats’ abandoned food in safety. The drongo maintains this working trust by only practicing his deceitful behaviour in the winter months, when food is scarce, providing honest protection for the rest of the year.

And those are not the only tales of avian intelligence. According to Nathan Emery’s summary of cognitive ornithology, birds are “exceptionally skilled at discriminating between visual images”. In fact, one study showed that pigeons can differentiate between paintings by different artists. Different avian species also exhibit tool-use, complex verbal mimicry, social learning and even numerical competence. Emery does point out, however, that there appears to be a significant gulf in intelligence between corvids and parrots and the rest of the avian world.

Nevertheless, science seems to show that there is a lot more going on in the brains of our feathered friends than we give them credit for. Perhaps being called a birdbrain isn’t such an insult after all.


IMAGE: Wikicommons