New Caledonian Crow - Corvus moneduloides

[Eaglehawk]

New Caledonian Crow - Corvus moneduloides



Scientific classification 
Kingdom: Animalia 
Phylum: Chordata 
Class: Aves 
Order: Passeriformes 
Family: Corvidae 
Genus: Corvus 
Species: Corvus moneduloides

The New Caledonian Crow (Corvus moneduloides) is a tool-using species of crow endemic to New Caledonia and the Loyalty Islands. These crows are the only non-primate animals known to invent new tools by modifying existing ones, and then passing these innovations on to other individuals in the cultural group. They have also been seen making tools that they use in the wild out of completely different material.

Distribution and habitat
The bird is endemic to the island of New Caledonia and the Loyalty Islands in the Pacific, living in primary forest.



Description
The New Caledonian Crow (Corvus moneduloides) is a moderately sized crow (40 cm in length) similar in size to the House Crow but less slender looking. The bird is all black with a rich gloss to the feathers of purple, dark blue and some green in good light. The beak, feet and legs are all black too. The beak is of moderate size but is unusual in that the tip of the lower is angled up making it somewhat chisel-like in profile.

The ability to fashion tools had always been held as unique to primates, distinguishing humans and their closest relatives from (apparently) less intelligent creatures. But humans and apes are not alone in having tool-making skills. Crows amazed the science community when footage recorded using tiny "crow-cams" on the tails of New Caledonian crows showed the birds creating advanced implements. One crow was observed whittling twigs and leaves with its beak to fashion grabbers designed to retrieve grubs from the ground. The New Caledonian crows are the only known non-primate to create and use new tools

The voice is described as a soft waa-waa or wak-wak, sometimes a hoarse waaaaw.

Ecology and behavior
It eats a very wide range of food including many types of insects and other invertebrates (some caught in flight with some agility, including night-flying insects which it catches at dusk), eggs and nestlings, snails (which it drops from a height onto hard stones), and various nuts and seeds. It is known for using plant material to create hooks or barbs for extracting grubs from inside logs and branches. This bird fills in the ecological niche of the woodpeckers and the Woodpecker Finch of the Galapagos, since the latter and New Caledonia lack woodpeckers. Unlike the Woodpecker Finch, however, it does not simply stab a grub and lever it slowly out of its log using a small twig but pokes the twig at the grub to agitate it into biting the twig. It shows great ingenuity in the search for food.

Its nest is built high in a tree with usually only 2 eggs laid from September to November.

Tool making
The New Caledonian Crow is the only non-human species with a record of inventing new tools by modifying existing ones, then passing these innovations to other individuals in the cultural group. Gavin R. Hunt and colleagues at the University of Auckland studied tools the crows make out of pandanus (or screw pine) leaves:

Crows snip into the leaf edges and then tear out neat strips of vegetation with which they can probe insect-harboring crevices. These tools have been observed to come in three types: narrow strips, wide strips and multi-stepped strips—which are wide at one end and, via a manufacturing process that involves stepwise snips and tears, become narrow at the opposite end.
Observations of the distribution of 5,500 leaf counterparts or stencils left behind by the cutting process suggest that the narrow and the stepped tools are more advanced versions of the wide tool type. "The geographical distribution of each tool type on the island suggests a unique origin, rather than multiple independent inventions". This implies that the inventions, which involve a delicate change in the manufacturing process, were being passed from one individual to another.

The New Caledonian Crow also spontaneously makes tools from materials it does not encounter in the wild, the only non-human species known to do so. In 2002, researcher Kacelnik and colleagues at the University of Oxford observed of a couple of New Caledonian Crows called Betty and Abel:

Betty's toolmaking abilities came to light by accident during an experiment in which she and Abel had to choose between a hooked and a straight wire for retrieving small pieces of pig heart, their favorite food. When Abel made off with the hooked wire, Betty bent the straight wire into a hook and used the tool to lift a small bucket of food from a vertical pipe. This experiment was the first time the crows had been presented with wire.
Subsequently, this ability was tested through a series of systematic experiments. Out of ten successful retrievals, Betty bent the wire into a hook nine times. Abel retrieved the food once, without bending the wire. The process would usually start with Betty trying to get the food bucket with the straight wire, but then she would make a hook from it bending it in different ways, usually by snagging one end of the wire under something, and then using the bent hook to pick up the tray.

Clearly, Betty's creation of hooks cannot be attributed to the shaping or reinforcement of randomly generated behavior. In 2004, Gavin Hunt observed the crows in the wild also making hooks, but the adaptation to the new material of the wire was clearly novel, and also purposeful. This type of intentional tool-making, even if it is generalizing a prior experience to a completely new context, is almost unknown in the animal world. Chimpanzees have great difficulty in similar innovative tasks.

Meta-tool use
Recent experiments show that New Caledonian Crows are able to use one tool to affect another to achieve a task, at a level rivalling the best performances seen in primates.

The experiment was conducted by the Auckland team and involved putting food in a box out of reach of the crows. They were given a stick too short to reach the food, but they could use this to retrieve a longer stick from another box. The longer stick was then used to retrieve the food. This complex behaviour involved realising that a tool could be used on non-food objects, and suppressing the urge to go directly for the food. It was solved by six of seven birds on the first attempt, and had previously only been known in primates.

[Eaglehawk]

After using tools, crows behave more optimistically, study suggests

by Peter Reuell, Harvard University


Credit: CC0 Public Domain

It's no secret crows are smart. They're notorious for frustrating attempts to keep them from tearing into garbage cans; more telling, however, is that they are one of the few animals known to make tools.

But would you believe doing it actually makes them happy?

That's the finding of a recent paper, co-authored by Dakota McCoy, a graduate student working in the lab of David Haig, George Putnam Professor of Biology, who found that crows behaved more optimistically after using tools. The study is described in an Aug. 19 paper in Current Biology.

"What this suggests is that, just the same way we enjoy something like solving a crossword, they actually enjoyed simply using a tool," McCoy said. "I think it suggests there's a lot more going on in that little head than we think. They get satisfaction out of doing things they're good at, have trained for their whole lives, and that they use frequently."

While tool use in the animal kingdom is not unheard of—chimps use sticks to "fish" for termites and other animals use rocks to smash open nuts or shells—New Caledonian crows stand out for manufacturing multiple complex tools and regularly refining their designs.

But how can making and using tools make an animal feel good? A clue, McCoy said, lies in looking at how complex actions make humans feel.

"I think we tend to under-anthropomorphize animals, especially really intelligent animals," she said. "It's not that they are machines, and we are feeling beings. Clearly, animals also have emotional reactions and moods."

And one of those emotions is the pleasure of accomplishment.

"One potential answer for why tool use evolved is because crows are used to picking up objects and caching them," she said. "They actually love, when you're experimenting with them, to pick up your equipment and cache it way up high where you can't get it."

Once crows started using tools, she said, the fact that it made them feel good encouraged them to keep at it, refining and developing the behavior further.

"Maybe crows are just like humans and other primates in that, when they're doing these complicated actions, they're reinforced not just by getting a prize out of it, but because they actually enjoy the process itself," she said.

To understand how crows felt about using tools, McCoy and colleagues devised an experiment to test how optimistic the birds were feeling.

"We do have subtle ways to test mood, and the classic paradigm is a glass half filled with water," she said. "Someone who is feeling pessimistic will interpret it as half empty, while an optimistic person will see it as half full."

For the crows, researchers conceived a similar test.

In the lab, crows were trained using a small box. When placed on the left side of a table, the box always contained a large reward—three pieces of meat. On the right side, it contained just a scrap of meat, a far smaller reward.

Once the crows understood the difference, researchers placed the box in the middle of the table. If the birds quickly came to investigate that ambiguous box, it suggested they were optimistic that they would find a large reward. If they waited or didn't visit the box at all, it suggested they were more pessimistic.


Credit: Cody McCoy

To test how they felt about tool use, the crows were then put through a series of tests over a number of days—one in which they had to use a tool to extract a piece of meat from a box and another in which the meat was readily available.

"But we thought that it might not be that tool use puts them in a good mood, it could be just that they had to work harder," McCoy said. "So we [added] two more conditions. In one the meat was right on the table so there was no effort involved, and in another "effortful" condition, they had to fly around to the four corners of the room to retrieve each piece of meat."

The results, she said, showed that, following tool use, the birds were much quicker to approach the ambiguous box, and much less enthusiastic after the effortful test compared to the easy test.

"They enjoyed the easy condition, that was no surprise," McCoy said. "But the surprise was that, clearly, they don't just like tool use because it's difficult. We controlled for difficulty and that wasn't what was motivating their interest—there is something specific about tool use they're enjoying."

While it's impossible to say for certain exactly what the birds were feeling, McCoy said her study is far from the first to attempt to gauge what effects animals' moods.

"Many people have done studies about what kind of mood animals are in … but the research to date has almost exclusively been on captive animals, and what kind of circumstantial changes can improve their mood," she said. "Many people have shown that animals' mood improves if you do something like give them a larger cage, but this study shows that animals also have a better mood if you give them complex, fun tasks to do."

McCoy, who is a student in the Graduate School of Arts and Sciences, said that she hopes to see the findings of the study applied to improving the lives of animals in captivity.

"Our findings suggest that one way to improve the welfare of captive animals is to give them complex, species-specific enrichment where they're using skills they have … to achieve goals instead of just receiving passive enrichment," she said. "We're far from a world where we don't have animals in captivity … but they could live a much more enriching life if they're housed socially and given fun tasks to solve."

phys.org/news/2019-08-tools-crows-optimistically.html

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Journal Reference:
Dakota E. McCoy et al. New Caledonian Crows Behave Optimistically after Using Tools, Current Biology (2019). DOI: 10.1016/j.cub.2019.06.080

Summary
Are complex, species-specific behaviors in animals reinforced by material reward alone or do they also induce positive emotions? Many adaptive human behaviors are intrinsically motivated: they not only improve our material outcomes, but improve our affect as well. Work to date on animal optimism, as an indicator of positive affect, has generally focused on how animals react to change in their circumstances, such as when their environment is enriched or they are manipulated by humans, rather than whether complex actions improve emotional state. Here, we show that wild New Caledonian crows are optimistic after tool use, a complex, species-specific behavior. We further demonstrate that this finding cannot be explained by the crows needing to put more effort into gaining food. Our findings therefore raise the possibility that intrinsic motivation (enjoyment) may be a fundamental proximate cause in the evolution of tool use and other complex behaviors.

www.cell.com/current-biology/fulltext/S0960-9822(19)30840-1?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982219308401%3Fshowall%3Dtrue