The list of animals intelligent enough to use tools is a short one, but it’s recently gotten one species longer: the Hawaiian crow has been added to its ranks.
A new study has shown the Hawaiian crow using sticks and twigs as foraging tools, prodding the landscape around them in search of food in hard-to-reach places. The Hawaiian crow is also extinct in the wild, with only 130 of these birds in existence today – all of them in highly-protected captivity.
There’s another crow on the “tool-users” list, known as the New Caledonian crow, which Dr. Christian Rutz of Scotland’s University of St. Andrews has studied extensively.
“I’ve been studying New Caledonian crows for over 10 years now,” Dr. Rutz told BBC News. “There are more than 40 species of crows and ravens around the world and many of them are poorly studied. So I wondered if there were hitherto undiscovered tool users among them.”
Rutz (who gets bonus points for using the word “hitherto” in a sentence) and his team note that New Caledonian crows have straight bills and forward-facing eyes – features which might be adaptations for using tools. The Hawaiian crow has similar features, says Rutz, which made the species a perfect candidate for further study.
And speaking of studying a species, Dr. Rutz and his team had a unique opportunity in studying the Hawaiian Crow.
“We effectively tested the entire species,” Dr. Rutz said. “At the time, there were 109 crows in captivity – we tested all of them, presenting them with a foraging task.”
Rutz and his team surrounded the birds with porous logs, baited the logs with food, and ensured the bait was just out of the bird’s natural reach.
“They were able to pick up sticks from the aviary,” said Dr. Rutz, “and of all the birds we tested, 93% used [the sticks as] tools. This suggests this is a species-wide skill.”
And it gets even more remarkable, as Dr. Rutz continues: “[The Hawaiian crows] were incredibly dexterous in the way that they handled the sticks – shortened them when they were too long, and discarded them if they were not happy with them.”
One might assume that a bird of such intelligence might thrive in the wild, but the Hawaiian crow has not; instead, the species has suffered from habitat destruction and disease, among other factors. The last remaining 130 specimens are protected in captivity by San Diego Zoo Global, an organization which helps stave-off animal extinction through breeding programs and other protective measures. San Diego Zoo Global hopes to release all 130 of them back into the wild later in 2016.