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Study

Shaping of hooks in New Caledonian crows

Weir, Alex A. S.; Chappell, Jackie; Kacelnik, Alex

Science, 2002

Peer-reviewedcontrolled laboratory experimentlaboratory

What they did

A captive crow was presented with a small bucket of food at the bottom of a vertical tube and with straight and hooked lengths of wire. When the hooked wire was unavailable, her behaviour with the straight wire was recorded.

Studied in
Corvus moneduloides
Sample size
2 captive New Caledonian crowsThe reported bending behaviour came from one bird, Betty.

What they found

The bird bent straight wire into a hook and used it to lift the bucket out, repeatedly and in several variations.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The crow modified a novel material into a functional tool without prior training, suggesting flexible problem-solving rather than a fixed action pattern.

How NatureHQ reads it

For twenty years this was the headline example of animal insight, and it is still a remarkable observation. Later fieldwork complicated the story: wild New Caledonian crows routinely make hooked tools from plant material, so bending something into a hook is part of the species' behavioural repertoire rather than an invention on the spot. That reframing makes the result less astonishing and more interesting — it is evidence about what a species is prepared to do, not about a single genius bird.

Limitations

  • Essentially a single-animal result.
  • The bird had prior experience with hooked tools in the laboratory.
  • Later field data showed hook-making is species-typical, which changes how the behaviour should be read.

What happened afterwards

  • contested reanalysis

    Subsequent fieldwork showed that hook manufacture is widespread in wild New Caledonian crows, so the original "spontaneous invention" reading overstated the case.

What this study is used for on NatureHQ

One study can inform several subjects. Here is everywhere this one is cited.

Finding the paper

Published by: American Association for the Advancement of SciencePublished in Science or Science Advances (AAAS).

doi.org/10.1126/science.1073433

This reference was resolved automatically against Crossref and OpenAlex on 2026-08-11.

NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-09.