Endangered Hawaiian crow shows a knack
for tool use
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[September 19, 2016]
By Will Dunham
WASHINGTON (Reuters) - An endangered crow
species from Hawaii that already is extinct in the wild displays
remarkable proficiency in using small sticks and other objects to
wrangle a meal, joining a small and elite group of animals that use
Scientists said on Wednesday that in a series of experiments the crow,
known by its indigenous Hawaiian name 'Alala, used objects as tools with
dexterity to get at hard-to-reach meat, sometimes modifying them by
shortening too-long sticks or making tools from raw plant material.
"Tool use is exceedingly rare in the animal kingdom," evolutionary
ecologist Christian Rutz of the University of St Andrews in Scotland,
who led the study published in the journal Nature, said in an email.
The 'Alala (pronounced ah-la-lah) is the second crow species known to
naturally use tools. The other is the New Caledonian crow on New
Caledonia island in the South Pacific, which uses tools to extract
insects and other prey from deadwood and vegetation.
New Caledonian and Hawaiian crows share a common feature: unusually
straight bills. The researchers wondered whether this trait might be an
evolutionary adaptation for holding tools, akin to people's opposable
Scientists are trying to save the 'Alala from extinction. The remaining
131 birds are kept in two facilities on the Big Island of Hawaii and the
island of Maui.
"A range of factors may have contributed to the species' decline in the
late 20th century, including habitat change and disease," Rutz said.
Scientists have mounted a captive-breeding program and later this year
plan to release captive-reared birds on the Big Island, their former
home in the wild, to try to re-establish a wild population.
Humans are the most adept tool users. But our closest genetic cousins,
chimpanzees, use stick probes to extract ants, termites and honey.
Capuchin monkeys and macaques use stones to hammer open hard-shelled
nuts and shellfish, respectively. Egyptian vultures and black-breasted
buzzards use stone tools to crack open bird eggs for food. Even some
invertebrates, including digger wasps, hermit crabs and some spiders,
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A captive Hawaiian crow using a stick tool to extract food from a
wooden log is shown in this image released on September 14, 2016.
Courtesy Ken Bohn/San Diego Zoo Global/Handout via REUTERS
In experiments using 104 captive birds, the researchers presented
Hawaiian crows with a wooden log with multiple drilled holes and
crevices baited with small pieces of meat. The crows could see the
meat, but not reach it with their bill alone. The vast majority
spontaneously used sticks and other objects to probe for the hidden
food: 93 percent of adults and 47 of younger birds.
Link to research paper in the journal Nature:
(Reporting by Will Dunham; Additional reporting by Ben Gruber in
Miami; editing by Grant McCool)
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