Critically endangered crow shown to be a skilled tool user

Hawaiian Crow is a skilled tool user.
A captive Hawaiian Crow (‘Alala) uses a stick tool to extract food from a wooden log. Photo by Ken Bohn/San Diego Zoo Global.

New Caledonian Crow is not the only member of the crow family that’s a skilled tool user.

An international team of scientists and conservation experts has discovered a similar astonishing degree of dexterity in the critically endangered Hawaiian Crow, or ‘Alala.

The discovery was announced on September 14 in the journal Nature. Team members include researchers from the School of Biology at the University of St. Andrews, Scotland; the Institute for Conservation Research of San Diego Zoo Global; and the Department of Physics and Centre for Networks and Collective Behaviour at the University of Bath, England.

The ‘Alala was listed as an endangered species in 1967 and has been extinct in the wild since the early 2000s. The world population totals only 131 birds, all of which are kept in two facilities on the Big Island of Hawaii and Maui.

The crows in captivity are the subjects of a last-ditch breeding program that conservationists hope will preserve the species — and soon. Captive-reared ‘Alala are scheduled to be released on Hawaii Island later this year, re-establishing a wild population.

New Caledonian Crows live only on an island located northeast of Australia, in the South Pacific. The first detailed description of their remarkable tool-using habits was published in Nature 20 years ago (abstract). The crows use tools to extract insects and other prey from deadwood and vegetation.

“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,” says the new study’s lead scientist, Christian Rutz, of the University of St. Andrews.

By searching for the tell-tale characteristic among some of the lesser-known corvid species, Rutz quickly homed in on a particularly promising candidate for further investigation — the ‘Alala.

He contacted San Diego Zoo Global’s Hawaii Endangered Bird Conservation Program, and the two teams quickly agreed to conduct a collaborative project, to examine the tool-using skills of ‘Alala under controlled conditions.

“We tested 104 of the 109 ‘Alala alive at the time and found that the vast majority of them spontaneously used tools,” says Bryce Masuda, co-leader of the study and conservation program manager for San Diego Zoo Global. Workers at the Keauhou and Maui captive-breeding facilities had previously seen birds using stick tools but hadn’t thought much of it.

“Using tools comes naturally to ‘Alala,” says Rutz. “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. In many regards, the ‘Alala is very similar to the New Caledonian Crow, which my team has been studying for over 10 years.”

As crow species go, the ‘Alala and New Caledonian Crow are only very distantly related, he explains. “With their last common ancestor living around 11 million years ago, it seems safe to assume that their tool-using skills arose independently.”

“It is striking that both 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!”

Tool use is extremely rare in the animal kingdom. According to estimates, the behavior has been documented in less than one percent of all known genera, and in an even smaller percentage of species.

Read the paper

Christian Rutz, Barbara C. Klump, Lisa Komarczyk, Rosanna Leighton, Joshua Kramer, Saskia Wischnewski, Shoko Sugasawa, Michael B. Morrissey, Richard James, James J. H. St. Clair, Richard A. Switzer, and Bryce M. Masuda (2016). Discovery of Species-wide Tool Use in the Hawaiian Crow. Nature 537, 403–407.

Read about the ‘Alala program of the San Diego Zoo Institute for Conservation Research.

Hawaiian honeycreeper populations are collapsing on Kauai (9/7/2016).

Study: Climate change and avian malaria are shrinking the ranges of Hawaii’s native birds (12/8/2015).

Hawaii’s new birding trail and festival (5/9/2016).

 

New to birdwatching?

Sign up for our free e-newsletter to receive news, photos of birds, attracting and ID tips, descriptions of birding hotspots, and more delivered to your inbox every other week. Sign up now.

See the contents of our current issue.

How to subscribe to BirdWatching.

 

Read our newsletter!

Sign up for our free e-newsletter to receive news, photos of birds, attracting and ID tips, and more delivered to your inbox.

Sign Up for Free