New Caledonian Crow
Encyclopedia
The New Caledonian Crow (Corvus moneduloides) is a tool-using species
of crow
endemic to New Caledonia
and the Loyalty Islands
. These crows are some of the only non-primate animals known to invent new tool
s 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.
(40 cm in length) similar in size to the House Crow
but less slender-looking. The bird has an all-black appearance with a rich gloss to its feathers of purple, dark blue and some green in good light. The beak
, feet and legs are all black. 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 primate
s. 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 among few known non-primates to create and use new tools.
The voice is described as a soft "waa-waa" or "wak-wak", and sometimes as a hoarse "waaaaw".
and the Loyalty Islands
in the Pacific, living in primary forest.
s (which it drops from a height onto hard stones), and various nut
s and seed
s. 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 woodpecker
s 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 2 dozen eggs laid from September to November.
s 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:
Observations of the distribution of 5,500 leaf
counterparts or stencil
s 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:
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.
The use of direct human activity has been recorded as well. This involves the placing of nuts in front of a vehicle on a heavy trafficked street and waiting for the/a car to crush it open, and then waiting at pedestrian lights with other pedestrians in order to retrieve the crushed nut safely.
s.
One such experiment, conducted by the Auckland team, involved putting food in a box out of the crows' reach. 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 observed in primates.
The crows also use tools to investigate potentially dangerous objects.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of crow
Crow
Crows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...
endemic to New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
and the Loyalty Islands
Loyalty Islands
The Loyalty Islands are an archipelago in the Pacific. They are part of the French territory of New Caledonia, whose mainland is away. They form the Loyalty Islands Province , one of the three provinces of New Caledonia...
. These crows are some of the only non-primate animals known to invent new tool
Tool
A tool is a device that can be used to produce an item or achieve a task, but that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such...
s 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.
Description
The New Caledonian Crow (Corvus moneduloides) is a moderately sized crowCrow
Crows form the genus Corvus in the family Corvidae. Ranging in size from the relatively small pigeon-size jackdaws to the Common Raven of the Holarctic region and Thick-billed Raven of the highlands of Ethiopia, the 40 or so members of this genus occur on all temperate continents and several...
(40 cm in length) similar in size to the House Crow
House Crow
thumb|300px|Bangalore, IndiaThe House Crow , also known as the Colombo Crow is a common bird of the Crow family that is of Asian origin but now found in many parts of the world, where they arrived assisted by shipping. It is between the Jackdaw and the Carrion Crow in size but is relatively...
but less slender-looking. The bird has an all-black appearance with a rich gloss to its feathers of purple, dark blue and some green in good light. The beak
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
, feet and legs are all black. 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 primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s. 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 among few known non-primates to create and use new tools.
The voice is described as a soft "waa-waa" or "wak-wak", and sometimes as a hoarse "waaaaw".
Distribution and habitat
The bird is endemic to the island of New CaledoniaNew Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
and the Loyalty Islands
Loyalty Islands
The Loyalty Islands are an archipelago in the Pacific. They are part of the French territory of New Caledonia, whose mainland is away. They form the Loyalty Islands Province , one of the three provinces of New Caledonia...
in the Pacific, living in primary forest.
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, small mammals, snailSnail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s (which it drops from a height onto hard stones), and various nut
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
s and seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s. 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
Ecological niche
In ecology, a niche is a term describing the relational position of a species or population in its ecosystem to each other; e.g. a dolphin could potentially be in another ecological niche from one that travels in a different pod if the members of these pods utilize significantly different food...
of the woodpecker
Woodpecker
Woodpeckers are near passerine birds of the order Piciformes. They are one subfamily in the family Picidae, which also includes the piculets and wrynecks. They are found worldwide and include about 180 species....
s and the Woodpecker Finch
Woodpecker Finch
The Woodpecker Finch, Camarhynchus pallidus, is a species of bird in the Darwin's finch group of the tanager family Thraupidae. Woodpecker Finches occur widely in the Galapagos Islands, from sea level to high elevations....
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 2 dozen eggs laid from September to November.
Tool making
The New Caledonian Crow is the only non-human species with a record of inventing new toolTool
A tool is a device that can be used to produce an item or achieve a task, but that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such...
s 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
University of Auckland
The University of Auckland is a university located in Auckland, New Zealand. It is the largest university in the country and the highest ranked in the 2011 QS World University Rankings, having been ranked worldwide...
studied tools the crows make out of pandanus
Pandanus
Pandanus is a genus of monocots with about 600 known species. They are numerous palmlike dioecious trees and shrubs native of the Old World tropics and subtropics. They are classified in the order Pandanales, family Pandanaceae.-Overview:...
(or screw pine) leaves:
Observations of the distribution of 5,500 leaf
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
counterparts or stencil
Stencil
A stencil is a thin sheet of material, such as paper, plastic, or metal, with letters or a design cut from it, used to produce the letters or design on an underlying surface by applying pigment through the cut-out holes in the material. The key advantage of a stencil is that it can be reused to...
s 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
University of Oxford
The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...
observed of a couple of New Caledonian Crows called Betty and Abel:
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.
The use of direct human activity has been recorded as well. This involves the placing of nuts in front of a vehicle on a heavy trafficked street and waiting for the/a car to crush it open, and then waiting at pedestrian lights with other pedestrians in order to retrieve the crushed nut safely.
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 primatePrimate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
s.
One such experiment, conducted by the Auckland team, involved putting food in a box out of the crows' reach. 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 observed in primates.
The crows also use tools to investigate potentially dangerous objects.
External links
- Oxford University crow research web site, including photos and movies
- Auckland University crow web page, an introduction to their field-based research on crows' tool manufacture and use, including video footage of meta-tool use
- From National Geographic: A video of the New Caledonian Crow making a hook out of wire (August 8, 2002)
- Tool use in crows is a combination of natural ability and schooling by other crows – LiveScience.com (October 31, 2006)
- BBC news website item about the New Caledonian Crow, includes video footage of tool use (August 16, 2007)
- Crow bends wire on purpose to lift bucket from glass tube (Nat'l Geo link no longer contains video). -- YouTube