• Robb G. Best

Something to Crow About

For decades, we've heard anecdotal evidence of the unnerving intelligence of birds in the corvid family: crows, ravens, jackdaws, and so on. If a raven notices another raven watching it hide its food, the raven will pretend to hide the food elsewhere. Wild jackdaws can recognize individual human faces. Author Jean Craighead George once had a family pet crow that figured out how to take a ride down the backyard slide by using a coffee can lid as a sled.

Now, new research suggests that crows are aware of what they know and can ponder their own thoughts. This was previously thought to be a distinction between humans and other animals, much like how we used to classify tool use as proof we were more evolved than other creatures. (Interestingly, crows have also been observed using hooked sticks to reach grubs.)

Neurobiologist Andreas Nieder of the University of Tübingen in Germany trained two crows to peck at either a red target or a blue target on a panel when they saw a blinking light. Nieder would periodically change up the rules (whether the flash of dim light should prompt a pecking on the red or the blue) only after the light had already flashed. This required the birds to continue monitoring their brains, with a second or two to figure out what they'd seen and which target they should press to tell Nieder.

Meanwhile, researchers tracked the activity of hundreds of neurons in each crow. (A crow brain has about 1.5 billion neurons; far less than the 86 billion neurons in the average human brain, but about the same as some species of monkey.)

When the crows indicated that they'd seen a light, sensory neurons were active between the blink of the light and the crow's report using the blue or red target. When the crow didn't see a light, those neurons were inactive, and they pecked the appropriate target to say they hadn't seen it. During that space of time before pressing the target, a large number of neurons reacted according to what the crow was about to report, instead of to the brightness of the light.

In other words, the birds had awareness of their own perceptions. “I think it demonstrates convincingly that crows and probably other advanced birds have sensory awareness, in the sense that they have specific subjective experiences that they can communicate,” said Nieder. “Besides crows, this kind of neurobiological evidence for sensory consciousness only exists in humans and macaque monkeys.”

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