Crows Prove Their Smarts With Twig Tools

A captive Hawaiian crow ('Alalā) using a stick tool to extract food from a wooden log.

Hawaiian crows are among the top tool users in the animal kingdom, according to a new study that also suggests life on remote tropical islands promotes particularly industrious birds.

The critically endangered Hawaiian crow, called 'Alalā by Hawaiians, is now the second island bird found to be clever at crafting and using tools, according to the study, which is published in the journal Nature. The other is the New Caledonia crow, which also hails from a remote, tropical island.

At first researchers thought the New Caledonia crow's tool skills were a fluke of nature, but now they suspect otherwise.

The new discovery "raises the intriguing possibility that there are some undiscovered (bird) tool users out there," project leader Christian Rutz from the University of St. Andrews said in a press release. "We had previously noticed that New Caledonian crows have unusually straight bills, and wondered whether this may be an adaptation for holding tools, similar to humans' opposable thumb."

There are only just over 100 Hawaiian crows left in the world, and all are in captivity via the San Diego Zoo Global's Hawai'i Endangered Bird Conservation Program. They were taken from the wild and brought to San Diego as a last ditch effort to preserve the species through a captive breeding program.

Later this year, some of the birds will be released on the big island of Hawaii to re-establish a wild population, according to Bryce Masuda, who co-led the new research and is conservation program manager of the San Diego program.

Rutz contacted Masuda about analyzing the crows' the tool use before the birds head back to Hawaii.

"We had occasionally seen birds using stick tools at our two breeding facilities, but hadn't thought much of it," Masuda said. "We tested 104 of the 109 'Alalā alive at the time, and found that the vast majority of them spontaneously used tools."

The below unedited scene shows an adult male Hawaiian crow presented with a tool challenge:

Masuda and the other researchers believe that the tool use is part of the species' natural behavioral repertoire, rather than being a quirk that arose in captivity.

During the study, the skill even revealed a bit of drama, showing how the very social birds interact with each other, and perhaps get on each other's nerves from time to time. The following video begins with several scenes of captive Hawaiian crows ('Alalā) using stick tools to extract food from a wooden log. In the second scene, a pair can be seen interacting during the task. The female (on the right-hand side) picks up a stick to use as a tool, but the male (on the left) steals it. The male then uses the tool to extract food, which the female steals!

"Using tools comes naturally to 'Alalā," Rutz explained. "These birds had no specific training prior to our study, yet most of them were incredibly skilled at handling stick tools, and even swiftly extracted bait from demanding tasks."

The birds don't just use the tools; they essentially make them through modifications. The birds were seen breaking twigs to just the right size, sharpening the tips and altering them in other ways to their advantage.

When many of us think of Hawaii, coveted vacations come to mind. Before humans came to dominate the islands and other problems arose (such as climate change, pollution, loss of habitat and introduction of other predatory animals) Hawaii, like New Caledonia, was a paradise for its native birds.

Tool selectivity, modification and manufacture by Hawaiian crows can be seen in this clip:

Rutz said, "It is striking that both (crow) species evolved on remote tropical islands in the Pacific Ocean that lack woodpeckers and ferocious bird predators -- perfect conditions, apparently, for smart crows to become accomplished tool users!"

Even very young birds have tool-using abilities:

World-renowned primatologist Jane Goodall is interested in the new study, as she was the first to document tool use in the wild. Before she and her team determined that wild chimps regularly craft and use tools, it was widely believed that only humans could do such things.

Humans, of course, have taken tool use to a whole other level of complexity, but the essential skills -- ability to manipulate objects to meet the needs of a task and then to share that wisdom with others -- are present in dolphins, wild chimps and other animals.

Read more at Discovery News