Crows were in the news this week after scientists found they make decisions twice as fast as humans. That's only the start — here is what research says about one of the smartest animals on Earth, with every fact checked.
They never forget a face
In 2006, University of Washington researchers wore a "caveman" mask while trapping seven crows. Years later, crows that were never caught — and chicks born after the trapping — still scolded anyone wearing that mask, while ignoring a neutral one. More than ten years on, over half the campus crows still raised the alarm.
Some make hooks — like tiny engineers
New Caledonian crows shape twigs and leaf edges into hooked tools to fish insects out of wood. Hooked tools get them food 2 to 10 times faster than straight sticks. In a lab, one crow named Mango built a longer tool by joining three and even four separate pieces.
They solved Aesop's famous fable
In the old fable, a thirsty crow drops stones into a jug to raise the water. Real New Caledonian crows did this to reach a floating treat — choosing water over sand and sinking objects over floating ones. (They failed harder versions, so scientists call their understanding "sophisticated but incomplete".)
They can count out loud
In a 2024 study in Science, carrion crows learned to make exactly one to four calls when shown a number — and planned how many calls to make before they started.
They understand "nothing" as a number
Carrion crows placed an empty display just below "one" on their mental number line, and their brain cells responded to it like a number — something once thought to need a human-like mind.
They can wait for a better reward
Crows and ravens waited up to about 10 minutes for better food rather than grabbing what was in front of them. New Caledonian crows even picked the right tool for a task they would face 10 minutes later, ignoring a snack offered now.
A dead crow is a danger lesson
When American crows find a dead crow, they gather noisily around it — and then avoid that spot for food. In one study, they scolded a person seen near the dead bird for up to six weeks. Scientists think this teaches the group where danger is.
Their caws carry information
An analysis of 1,674 caws from wild American crows found that pitch and length change with the call's purpose — food, alarm, or telling off a begging youngster. A computer could even guess which bird was calling far better than chance.
Winter roosts can hold two million birds
In winter, American crows gather in huge night-time roosts — from hundreds of birds up to about two million. A single roost in Springfield, Ohio, holds an estimated 150,000 crows.
Grown-up crows help raise their siblings
American crow parents don't push their young away. Some stay five years or more, helping to feed new chicks and guard the territory. In one study of 350 nests, 80% had three or more adults helping.
Their brains are small but packed
Crow-family brains are small, but their neurons are tiny and tightly packed. A raven's 14-gram brain has about 1.2 billion neurons in its forebrain — more than a capuchin monkey's. Rooks, also members of the crow family, have about 918 million in an 8.4-gram brain.
They decide in a quarter of a second
In a study published in Science on 22 October 2026, carrion crows judged which way a cloud of dots was moving in an average of 235 milliseconds — about twice as fast as humans and monkeys in similar tests. Read the study explained → · Can you beat a crow? Try our reaction time test →
Crows hold funerals to mourn their dead.
Myth. Research shows the gatherings are about learning where danger is — there's no evidence crows grieve.
Crows can deliberately make an exact number of calls, up to four.
Fact. Carrion crows did exactly this in a 2024 study in Science.
Crows are as smart as a seven-year-old child.
Myth. The claim comes from one water puzzle, where crows matched young children on some versions and failed others — it's not a measure of overall intelligence.
Scientists have proved that crows drop nuts in traffic so cars will crack them.
Myth. It's not proven: in the Californian town where the story began, crows dropped walnuts just as often with no cars around.
Crows can treat "nothing" as a number.
Fact. Carrion crows placed an empty display just below one on their mental number line (Journal of Neuroscience, 2021).
Sources: Marzluff & Pecoraro, Proceedings of the Royal Society B (2012); Audubon; University of Edinburgh; University of Oxford; ScienceDaily; NPR; Kirschhock et al., Journal of Neuroscience (2021); Audubon on self-control; Boeckle et al., Proceedings B (2020); National Geographic; Bioacoustics (2015); Cornell University; Olkowicz et al., PNAS (2016); University of Tübingen; Cristol et al., The Auk (1997).
Which crow fact surprised you most? React below, and share this with someone who still uses "bird brain" as an insult.
