Scientists crowing about another
species of bird found to use tools
By Washington Post, adapted by Newsela staff on 09.20.16
Word Count 785
A captive Hawaiian crow carrying a stick tool to a wooden log where food is hidden in drilled holes. The crows have been
observed to modify their tools by shortening, and even to manufacture tools from raw plant materials. Photo: Ken Bohn,
San Diego Zoo Global
Scientists used to think only humans could use tools. Then Jane Goodall saw chimpanzees
using twigs as tools in 1960. She sent her coworker a message.
"Now we must redefine tool, redefine Man, or accept chimpanzees as humans," she said.
Tool Use Is Rare
Most people decided to redefine tool. Fifty years later, scientists now recognize primates,
elephants, dolphins, sea otters, and others as tool users. Tool use among animals is still
rare, though. It is found in less than 1 percent of all species.
This is why the discovery of a new tool user is big news. We now know the Hawaiian crow
holds twigs in its teeth to dig insects and other food out of hard-to-reach spots. It is the
second member of its genus known to do this.
Behavioral ecologist Christian Rutz is the lead author of this new study. He said that finding
a single species doing a behavior is difficult for a scientist. There's not a lot of room to go
from there. Finding a second species is exciting. Two species with similar behaviors could
prove evolutionary. Discoveries like this could eventually connect tool use in animals to tool
use in humans.
Looking For A Rare Bird
For more than 10 years, Rutz has been studying New Caledonian crows. They are the first
member of the genus Corvus known for natural tool use. Chicks from this species naturally
pick up twigs with their beaks. They use the twigs to scrape up food. They break off
branches and turn them into hooks or barbs. They were thought to be the only ones to do
this.
Rutz thought there may be others. He said, "There are over 40 species of crows and
ravens, and so many of them are understudied. I thought, 'OK, maybe one of them.'"
The trouble was figuring out which one. Many members of the genus live in small,
threatened communities on hard-to reach islands. Rutz couldn't fly all over and hope to
happen upon one by chance.
The Eyes Have It (The Beaks Too)
Then he had his moment of discovery. Unlike many other members of the Corvus genus,
New Caledonian crows have straight beaks. Straight beaks make it easier to handle twigs.
The crows also have incredibly big eyes and a large field of depth.
"I figured, if we search for straight bills and large eyes we can find other candidate
species," Rutz said.
The large, all-black Hawaiian crow is known on its home island as 'alala. It has a straight,
flat beak. Its eyes are small but extremely forward-facing, allowing for a good depth of
field. Rutz called the program manager at a center in Hawaii run by the San Diego Zoo.
Hatching A Plan
"I said, 'Look, this may sound a bit crazy but I have a hunch your birds may be tool users.'
And the guy replied, 'Oh yeah, they do all sorts of funny things with sticks.' "
Rutz and his co-workers designed experiments to test whether the crows were natural tool
users. They observed more than 100 adult crows and found that 93 percent spontaneously
picked up sticks to dig for hard-to-reach food. In another test, hatchlings were kept from
adults. Without training or examples, the young crows picked up and played with sticks,
then figured out how to use them.
"That strongly suggests that the species has genetic predispositions that lead to
development of functional tool use," Rutz said.
Curiosity Thrilled The Crow
This doesn't mean the crows have a "tool-use gene" or know from birth how to dig with a
stick.
More likely, birds are born with a curiosity about objects, much like human toddlers.
The Hawaiian and New Caledonian crows live almost 4,000 miles apart. This could be an
example of two species separately evolving the same habit. Both species share similarities
with another well-known natural tool user, the Galapagos woodpecker finch. All three are
tropical species, living on small islands with few predators competing for the insects they
love to eat.
Conservation Is An Important Tool
"Now we can cautiously start constructing evolutionary arguments about the origins of tool
use," Rutz said. "And of course, ultimately this enables much broader comparisons with
non-tool using species, with primates."
We came close to never knowing this discovery. Wild Hawaiian crows have been dying out
since the early 2000s. The only representatives of the species remaining are raised in
confinement by conservationists from the San Diego Zoo. There are 109 known Hawaiian
crows still alive.
"Let this discovery serve to emphasize the importance to conserving these and other
animal species," said Goodall, the mother of animal tool use research. "These discoveries
show how much there is still to learn about animal behavior."
Quiz
1
Which section explains that it is difficult to study the various types of crows?
(A)
“Tool Use Is Rare”
(B)
“Looking For A Rare Bird”
(C)
“The Eyes Have It (The Beaks Too)”
(D)
“Hatching A Plan”
2
Select the paragraph from the section “The Eyes Have It (The Beaks Too)” that BEST explains
why Rutz chose to study Hawaiian crows.
3
Read the section “Tool Use Is Rare.” Which sentence BEST supports the CENTRAL idea that
studying the Hawaiian crow might lead to bigger scientific understanding?
4
(A)
Tool use among animals is still rare, though.
(B)
We now know the Hawaiian crow holds twigs in its teeth to dig insects and
other food out of hard-to-reach spots.
(C)
He said that finding a single species doing a behavior is difficult for a
scientist.
(D)
Discoveries like this could eventually connect tool use in animals to tool use
in humans.
How does the author support the CENTRAL idea that conserving animal species is important?
(A)
by stating that all the crows Rutz studied live in captivity and describing their
unnatural conditions
(B)
by describing what the Hawaiian crow has had to do in order to survive on
the dangerous tropical islands
(C)
by explaining that the discovery almost did not happen because there are
so few Hawaiian crows left
(D)
by calling Jane Goodall the "mother of animal tool research"
Answer Key
1
2
Which section explains that it is difficult to study the various types of crows?
(A)
“Tool Use Is Rare”
(B)
“Looking For A Rare Bird”
(C)
“The Eyes Have It (The Beaks Too)”
(D)
“Hatching A Plan”
Select the paragraph from the section “The Eyes Have It (The Beaks Too)” that BEST explains
why Rutz chose to study Hawaiian crows.
Paragraph 10:
The large, all-black Hawaiian crow is known on its home island as 'alala. It has a
straight, flat beak. Its eyes are small but extremely forward-facing, allowing for a
good depth of field. Rutz called the program manager at a center in Hawaii run
by the San Diego Zoo.
3
4
Read the section “Tool Use Is Rare.” Which sentence BEST supports the CENTRAL idea that
studying the Hawaiian crow might lead to bigger scientific understanding?
(A)
Tool use among animals is still rare, though.
(B)
We now know the Hawaiian crow holds twigs in its teeth to dig insects and
other food out of hard-to-reach spots.
(C)
He said that finding a single species doing a behavior is difficult for a
scientist.
(D)
Discoveries like this could eventually connect tool use in animals to
tool use in humans.
How does the author support the CENTRAL idea that conserving animal species is important?
(A)
by stating that all the crows Rutz studied live in captivity and describing their
unnatural conditions
(B)
by describing what the Hawaiian crow has had to do in order to survive on
the dangerous tropical islands
(C)
by explaining that the discovery almost did not happen because there
are so few Hawaiian crows left
(D)
by calling Jane Goodall the "mother of animal tool research"