Anyone who has ever been around the critically endangered Hawaiian crow, or alala, knows how smart they are.
Turns out the native birds are even more astute than previously believed.
A study published Thursday in the journal Nature reveals that the alala is a “remarkable” and “dexterous” user of tools — an ability found in only a handful of other bird species and in less than 1 percent of all animals.
“They are extremely intelligent,” said Bryce Masuda, manager of the Hawaii Endangered Bird Conservation Program, which oversees the captive alala propagation project for the Institute for Conservation Research, with facilities on Hawaii island and Maui.
Masuda and five other Institute for Conservation Research scientists on Hawaii island, on Maui and in San Diego joined six researchers from the University of St. Andrews in the United Kingdom and one from the University of Bath in the U.K. in conducting the tool-use experiments.
The results come two months before the planned release of alala into the wild for the first time in more than two decades.
A successful release of a dozen of the birds at Puu Makaala Natural Area Reserve on Hawaii island will mean it will be the first time the Hawaiian crow will exist in a Big Island forest since the last pair vanished in South Kona in 2002.
In the previous decade the alala was down to only 20 individuals and on the cusp of extinction, the victim of habitat loss and predators such as rats and mongoose.
Today the world’s population of alala numbers 131, all of which are housed in two facilities on Hawaii island and Maui.
Masuda said his team, having observed the birds for years in captivity, already knew they could use tools, or sticks, when Christian Rutz of St. Andrews called him in 2013. Rutz told him he strongly suspected Hawaiian crows use tools when they forage for food.
What the Hawaii team didn’t know, Masuda said, was just how adept the crows were at handling tools.
In experiments involving all of the alala population at the time, researchers found that 93 percent of the adult birds could use sticks to extract food from holes and crevasses in logs.
“They could do it in less than a minute,” he said.
Although the youngest birds could not do it, they could once they matured enough to figure it out at about the age of 3, Masuda said.
According to the study, at least two lines of evidence suggest that tool use is part of the species’ natural range of behavior: the capacity for proficient tool use species-wide and the fact juveniles learn to use tools without training or input from adults.
Rutz, the lead author, whose academic group studies the ecology and evolution of tool use in animals, for years had been studying the New Caledonian crow, the only other member of the genus Corvus known for using tools. (New Caledonia is a French territory comprising a group of South Pacific islands.)
Reports of New Caledonian crows using foraging tools were published in 1928 and 1972.
“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,” Rutz said in a news release issued by St. Andrews.
He decided to search for other straight-billed corvid species and eventually zeroed in on the Hawaiian crow for further investigation.
Rutz’s hunch was confirmed by the study accomplished in collaboration with the Hawaii researchers.
The study, published as the cover story in Nature on Thursday, says the alala and the New Caledonian crows, while only distantly related, both evolved independently in similar environments on remote tropical islands, where conditions may have allowed for the development of tool use.
The scientists eventually want to learn how humans evolved to exhibit superior tool-using skills. But to achieve this, they say, other tool-using species are needed for comparison, which is why the discovery of a second tool-using crow species is so important.
Beyond the greater implications for the study of tool-use evolution, Masuda said the study is important for the alala as a species.
“It shows that we’re still learning so much about the alala,” he said. “It adds to our knowledge and gives us a greater appreciation of how unique and significant it is.”
Masuda said researchers already knew the alala is smarter than the average bird. For example, the alala uses a vast number of calls and vocalizations, more than any other raven or crow — a family of birds with an established reputation for being intelligent.
“That’s a huge language,” he said.
The alala is also known for being able to store away food under a rock, for example, and then retrieve it at a later time, Masuda said.
The Hawaii Endangered Bird Conservation Program is a field program of the San Diego Zoo’s Institute for Conservation Research, in partnership with the state Division of Forestry and Wildlife and the U.S. Fish and Wildlife Service, with additional funding from the Moore Family Foundation, Marisla Foundation, several anonymous donors and San Diego Zoo Global.
In addition to Masuda, the Hawaii researchers who contributed to the study were Lisa Komarczyk and Rosanna Leighton of the Keauhou Endangered Bird Conservation Center in Volcano and Joshua Kramer from the Maui Endangered Bird Conservation Center in Olinda.
The St. Andrews release quoted primatologist Jane Goodall, who studied tool use in primates. She said she’s exited about the alala study.
“I love learning about the discovery of tool-use behaviours in other species of animals. This latest finding is especially wonderful. With two tool-using corvids, the well-known Galapagos finches, and one vulture in the list of tool using birds, we can now make comparisons with avian and primate tool using. Each of these discoveries shows how much there is still to learn about animal behavior, and it makes me re-think about the evolution of tool use in our own earliest ancestors.”
