New Study: Crows More Upbeat After Using Tools

Written by Mike Mcpherson
Published: October 16, 2021
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You know that glow of pride and satisfaction after completing a puzzle? That mood booster when you conquer a difficult brain teaser by appealing to your intelligence and creativity to problem solve? That lingering joy, it turns out, isn’t singularly human. A new study concludes crows using tools also experience an upbeat buzz.

Harvard graduate student Dakota McCoy co-authored the study after conducting a series of experiments using crows in the lab of Biology Professor David Haig. She discovered crows became more optimistic following the completion of a tricky task rather than a simple or physically intensive one.

How To Test Crows For Optimism?

The experiment worked like this: First, McCoy captured 15 wild crows on the island of New Caledonia off the eastern coast of Australia. Then, the birds were presented regularly with little boxes of food. Whenever a box was placed on the right side of the room, it contained a greater amount of meat than when placed on the left side. The subjects quickly determined the pattern, indicated by a certain degree of hesitancy when presented with a box on the left side.

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After establishing the pattern, boxes were placed in the center of the space, where they had not been placed previously. Given the behavioral difference between interactions with left and right side boxes, researchers determined the speed with which a bird approached the box indicated its level of optimism. The faster they removed the top to peek inside, the more optimistic they were about finding treats.

Prior to the introduction of a centrally placed mystery box, some subjects completed tasks to retrieve meat morsels with the use of tools. Crows strip twigs of leaves to use them as sticks in the retrieval of difficult to reach food. In the experiment, food was placed down a narrow tube while twigs were provided for crows to reach it.

The difference of reactions between the control group and the tool users revealed an uptick in optimism when presented with the mystery box. Birds that completed the task immediately before ventured to open the box on average nearly twice as fast as those that didn’t.

But to make sure it wasn’t the effort that made them hungrier, McCoy included other tasks that required effort rather than creativity. By placing meat in boxes mounted to the upper corners of the room, he tested whether simply working impacted their optimism. Those birds also waited longer than those that completed the twig task before checking out the mystery box.

“[T]he surprise was that, clearly, they don’t just like tool use because it’s difficult,” said McCoy. “We controlled for difficulty and that wasn’t what was motivating their interest—there is something specific about tool use they’re enjoying.”

Improving Conditions For Animals In Captivity

McCoy stated the research indicates a potential method of improving the lives of animals in captivity. While enlarging their living space has been shown to benefit their well-being, so, too, she argues, could introducing intellectually challenging activity. “Our findings suggest that one way to improve the welfare of captive animals is to give them complex, species-specific enrichment where they’re using skills they have,” she said.

A variety of animals employ tools to gather food. Bottlenose dolphins living in Shark Bay, Australia, for example, use sponges to disturb the ocean floor in search of prey. Sea otters bludgeon abalone shells with stones to open them. Gorillas press walking sticks into water to determine its depth. By providing animals in captivity, such as zoos, research facilities, and veterinarian hospitals, with fun puzzles that replicate skills observed in the wild, their handlers can offer a more satisfying existence.

Crows Using Tools In Complex Ways

This isn’t the first study to put New Caledonian crows to the test. A previous experiment sought to uncover just how far ahead these birds projected. To test their intelligence, researchers at the University of Auckland in New Zealand created a multi-level puzzle. It required the birds to first retrieve a stick from one module, then use it to gather a stone from a second module, which they then dropped into a third to dispense a bit of meat. Just to make this trickier, they also included a superfluous tool unnecessary to the completion of the puzzle.

The clever crows managed to successfully obtain the meat at the end of the test. Even after subtle changes, they adapted to updates and completed the puzzle again. They observed the test crows using tools in increasingly creative ways that indicated forethought. In speaking with National Geographic, a researcher not involved in the study spoke to its findings, saying, “It really goes to show how wrong we have been in using the term ‘bird brain’ as an insult.”

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FAQs (Frequently Asked Questions) 

How many animals use tools?

It’s a common misconception that very few, highly intelligent species use tools. In fact, a wide and varied array of creatures manipulate objects for personal gain. For example, wasps use pebbles to dig a hole in which to lay eggs. This sort of ingenuity pervades the whole of the animal kingdom, from tiny-brained insects to elephants that have used step stools in nursing. They use tools to reach into small spaces, to burrow, and as weapons to hunt.

Are crows the smartest bird species?

Species belonging to the corvid family, including crows, ravens, magpies, and jays, are generally considered the most intelligent among birds. Observed behavior in natural habitats and lab studies indicate a highly capable intelligence. Stacked up against contenders like different parrot species don’t measure up against the sheer problem solving exhibited by corvid family bird species.

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  2. Live Science, Available here:
  3. National Geographic, Available here:
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  5. CNET, Available here: