The video clips don’t last long, but there’s enough time to see the neurons firing.
The bird, an ‘alala (Hawaiian crow) wearing leg band No. 121, picks up a straight stick in its bill and pokes the stick into a log, probing until it maneuvers a piece of food close enough to be grabbed outright.
In another clip, a female bird snaps off a piece of branch to make a stick that’s the proper size for reaching food. A different clip shows two ‘alala tussling over a stick: one gets the stick and probes for the food, only to have the now-accessible morsel stolen away by its companion.
The videos are part of a study published today in the scientific journal Nature documenting tool use by the ‘alala — a milestone in animal behavior research.
“They do it completely on their own, spontaneously,” said Bryce Masuda, conservation program manager of the Keauhou Bird Conservation Center, one of two Hawaii breeding facilities for ‘alala.
The bird is extinct in the wild, but a cohort of juveniles will be released on Hawaii Island this fall in hope of re-establishing an ‘alala population.
Animal tool use is extremely rare. According to a release from the University of St. Andrews in Scotland, which led the ‘alala study, it has been reported in less than 1 percent of all species. Until 1964, when Jane Goodall published a paper documenting wild chimpanzees using twigs to “fish” for termites, it was widely thought only humans could use tools.
St. Andrews lead scientist Christian Rutz became interested in the crows’ tool use after noticing a sizable gap in avian research.
Tool use in the New Caledonian crow, a bird that lives only on the South Pacific island of New Caledonia, has been documented for decades, but the topic was not widely studied in other corvids (a family that also includes ravens, rooks, magpies and jays).
Biologists previously noted the “unusually straight” bills of New Caledonian crows, Rutz said in a statement, and “wondered whether this may be an adaptation for holding tools, similar to humans’ opposable thumbs.”
In searching for other corvid species with this feature, Rutz decided to investigate the ‘alala. He contacted Masuda and the Keauhou Bird Conservation Center.
The center’s researchers occasionally saw the birds using sticks to access food. They jumped at the chance to collaborate.
Under controlled conditions, more than 90 percent of the 104 adult birds tested displayed the tool-using behavior.
“These birds had no specific training prior to our study, yet most of them were incredibly skilled at handling stick tools,” Rutz said.
Study co-author Richard James of the University of Bath used computer simulations to demonstrate the unlikelihood of the behavior spreading through social learning, which can sometimes happen in captive populations.
“We keep them as wild as we can because we want to release them,” Masuda said.
The study also found differences in behavior among juvenile and adult crows.
“The young birds don’t use tools. They’ll pick up sticks, but they won’t use them,” Masuda said. “Not until they’re 2 or 3 years old, and then all of a sudden, they all do.”
“It’s just one more layer to the story of how amazing they are,” he said.
The ‘alala and New Caledonian crow are distantly related — their last common ancestor lived 11 million years ago. That gap makes it safe to assume their tool-using skills arose independently, Rutz said.
Through the University of St. Andrews, Goodall issued a statement of her own regarding the discovery, calling the finding “especially wonderful.”
“Each of these discoveries shows how much there is still to learn about animal behaviour, and it makes me rethink about the evolution of tool use in our own earliest ancestors,” she said.
The Keauhou Bird Conservation Center is part of the San Diego Zoo Institute for Conservation Research.
To read the Nature study, visit www.nature.com/nature/journal/v537/n7620/full/nature19103.html.
Email Ivy Ashe at iashe@hawaiitribune-herald.com.
