Animal cameo:
New Caledonian crow (Corvus moneduloides) New Caledonian crows are native to the islands of New Caledonia, a small archipelago in the South Pacific ocean (roughly half-way between Australia and Fiji). In appearance, they are fairly typical corvids (members of the crow family), resembling jackdaws although with blacker, glossy plumage. They also have a typically omnivorous corvid diet, eating everything from carrion and insects to fruit and nuts. However, aspects of their behaviour are unlike all other corvids, and have recently given them extensive media coverage around the world.
Until 10 years ago, these crows were little-noticed birds, with only a few short notes about them published in the scientific literature. In 1996, however, the New Zealand biologist Dr Gavin Hunt published a paper in the prestigious journal Nature that immediately thrust them into the limelight. He reported that wild New Caledonian crows made tools and used them to forage for invertebrates. Even tool use is rare amongst animals, although other birds (notably Galapagos woodpecker finches, Cactospiza pallida) do routinely use sticks and thorns to probe for food. The complex tool manufacture reported by Dr Hunt is, apart from humans, unparalleled in the animal kingdom. The crows are now known to make and use at least three sorts of tools in the wild, including straight twigs and leaf stems, hooked twigs, and complex tapering ‘cut-outs’ from pandanus leaves.
This behaviour may seem very clever, but does it necessarily reflect intelligence? Many animals show very sophisticated behaviour (such as making complex nests) without possessing exceptional cognitive abilities. To answer this question, researchers have given captive New Caledonian crows tool-related problems to examine how they solve them: do Five fascinating facts about New Caledonian they use trial-and-error learning, or can crows they work out the solution in advance It has been proposed that their cut-out pandanus tools without having to practice? This work is are the result of ‘cumulative cultural transmission’, still ongoing, but at least one crow has with the design passed down through generations. shown surprising abilities: when given a Like some other corvids, New Caledonian crows drop problem needing a hook, “Betty” can nuts onto stones and roads to break them open. spontaneously bend a piece of wire into However, these crows actually balance the nuts in a hook-shape, and use it to get the food. tree forks before dropping them, possibly to improve Moreover, she uses several different their aim! techniques to make hooks, The crows show “beakedness” in their manufacture and use of tools! Most crows seem to prefer to use the demonstrating that she has not just right-hand side of the beak when making pandanus- discovered one technique accidentally leaf tools. When using tools, there appears not to be a and repeated it. Even chimpanzees, our population-wide preference, but individual crows closest relatives, do not seem to be always hold tools in the same orientation. capable of this behaviour. New Caledonian crows’ bills are unusually straight for a corvid – perhaps an adaptation for using tools. Alex Weir Historically there were no large mammals in New University of Oxford Caledonia, and no woodpeckers, so crows’ tool use See http://users.ox.ac.uk/~kgroup/tools/tools_main.html for may have evolved to access protein-rich invertebrates more information and videos. living in burrows in trees.