So, which other crows had similar faces? Rutz started casually scanning images and videos, and he quickly homed in on the Hawaiian crow or alalā.

The quest could easily have ended there because the Hawaiian crow went extinct in the wild. Introduced predators, vanishing forests, and emerging diseases all contrived to turn this once-common bird into a memory, and the last wild pair vanished in 2002. Fortunately, some survived in captivity, and conservationists at San Diego Zoo Global have worked tirelessly to raise and breed the animals. As of 2013, 109 crows survived in two centers in Hawaii.

Rutz called them up. “This might sound crazy but I have a hunch that your birds might use tools,” he said. “Yeah, yeah, we’ve seen that,” they told him.

Sometimes the birds would use sticks to grab food that had fallen outside the mesh of their cages. Also, every year, the zoo staff try to weigh the birds by baiting a weighing scale with fruit—and the crows would often foil them by just raking the fruit off with a stick. Ironically, the staff figured that this was standard crow behavior because they had heard about the New Caledonian crows. Rutz, knowing differently, booked the first flight out to Hawaii.

He worked with two of the Hawaiian crows at first. After they quickly proved their proficiency, he tested the entire captive population of 109 birds using baited logs. He found that 93 percent of the adults were “very slick tool users”. They would deftly probe the holes with sticks on their first go, and within minutes of getting access to a log. Sure, some of them had used sticks to drag objects, but they had never had to pry food from holes. And yet, they routinely picked the right stick for the job, and some even modified their tools to improve them.

Many animal species can be trained to use tools in captivity even when they don’t do so naturally. That includes the rook—the Hawaiian crow’s closest relative. It can quickly learn to probe holes with sticks (albeit clumsily), but despite decades of regular bird-watching, no one has ever seen a wild rook use a stick tool.

The same could be said of Hawaiian crows, but Rutz says, “I truly believe that in the past, these birds would have used tools in the wild.” The captive adults all did so spontaneously and exactingly. Rutz even tested seven recently hatched chicks, which had never used sticks before and had no chances to observe tool-proficient adults. Their human keepers had been briefed to never use tools in front of them.

And yet, when confronted with a weekly baited log, all the chicks picked up nearby objects and tried their luck at probing. They were clumsy, but four of them became adept over a few months. “I think the evidence is overwhelmingly in support of this being natural tool-using behavior,” Rutz says.

Ken Bohn / San Diego Zoo Global

“The discovery of another tool-using crow species is exciting, especially the fact that the birds have a disposition to learn to use tools,” says Sabine Tebbich from the University of Vienna. The New Caledonian and Hawaiian crows are not close relatives, which suggests that their skills evolved independently. And that takes scientists closer to figuring out why tool use arises in some of birds and not others.