Only a handful of bird species are known to use foraging tools in the wild1. Amongst them, the New Caledonian crow (Corvus moneduloides) stands out with its sophisticated tool-making skills2,3. Despite considerable speculation, the evolutionary origins of this species’ remarkable tool behaviour remain largely unknown, not least because no naturally tool-using congeners have yet been identified that would enable informative comparisons4. Here we show that another tropical corvid, the ‘Alalā (C. hawaiiensis; Hawaiian crow), is a highly dexterous tool user. Although the ‘Alalā became extinct in the wild in the early 2000s, and currently survives only in captivity5, at least two lines of evidence suggest that tool use is part of the species’ natural behavioural repertoire: juveniles develop functional tool use without training, or social input from adults; and proficient tool use is a species-wide capacity. ‘Alalā and New Caledonian crows evolved in similar environments on remote tropical islands, yet are only distantly related6, suggesting that their technical abilities arose convergently. This supports the idea that avian foraging tool use is facilitated by ecological conditions typical of islands, such as reduced competition for embedded prey and low predation risk4,7. Our discovery creates exciting opportunities for comparative research on multiple tool-using and non-tool-using corvid species. Such work will in turn pave the way for replicated cross-taxonomic comparisons with the primate lineage, enabling valuable insights into the evolutionary origins of tool-using behaviour.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1.

    , & Animal Tool Behavior: the Use and Manufacture of Tools by Animals (Johns Hopkins Univ. Press, 2011)

  2. 2.

    Manufacture and use of hook-tools by New Caledonian crows. Nature 379, 249–251 (1996)

  3. 3.

    , & Hook tool manufacture in New Caledonian crows: behavioural variation and the influence of raw materials. BMC Biol. 13, 97 (2015)

  4. 4.

    & The evolutionary origins and ecological context of tool use in New Caledonian crows. Behav. Processes 89, 153–165 (2012)

  5. 5.

    , & in The Birds of North America , vol. 17 (eds & ) (The Birds of North America, Inc., 2002)

  6. 6.

    , , , & Genetic divergences and intraspecific variation in corvids of the genus Corvus (Aves: Passeriformes: Corvidae) – a first survey based on museum specimens. J. Zool. Syst. Evol. Res. 50, 230–246 (2012)

  7. 7.

    & in Tool Use in Animals: Cognition and Ecology. (eds , & ) (Cambridge Univ. Press, 2013)

  8. 8.

    , & (eds) Handbook of the Birds of the World. Bush-shrikes to Old World Sparrows , vol. 14 (Lynx Edicions, 2009)

  9. 9.

    , , , & Extreme binocular vision and a straight bill facilitate tool use in New Caledonian crows. Nat. Commun. 3, 1110 (2012)

  10. 10.

    Crows of the World (British Museum, 1976)

  11. 11.

    and Wildlife Service (USFWS). Revised Recovery Plan for the ‘Alalaˉ (Corvus hawaiiensis) (USFWS, 2009)

  12. 12.

    Wild voices in captivity: the fate of the ‘Alala. Birding 38, 64–67 (2006)

  13. 13.

    ‘Alala: weighing in. (2011)

  14. 14.

    et al. Adaptive bill morphology for enhanced tool manipulation in New Caledonian crows. Sci. Rep. 6, 22776 (2016)

  15. 15.

    , , & Tool manufacture by naive juvenile crows. Nature 433, 121 (2005)

  16. 16.

    , , & Development of tool use in New Caledonian crows: inherited action patterns and social influences. Anim. Behav. 72, 1329–1343 (2006)

  17. 17.

    et al. On the evolutionary and ontogenetic origins of tool-oriented behaviour in New Caledonian crows (Corvus moneduloides). Biol. J. Linn. Soc. 102, 870–877 (2011)

  18. 18.

    , , & The evolution of individual and cultural variation in social learning. Trends Ecol. Evol. 31, 215–225 (2016)

  19. 19.

    , & Ratcheting up the ratchet: on the evolution of cumulative culture. Phil. Trans. R. Soc. B 364, 2405–2415 (2009)

  20. 20.

    & Insightful problem solving and creative tool modification by captive nontool-using rooks. Proc. Natl Acad. Sci. USA 106, 10370–10375 (2009)

  21. 21.

    , & Foraging ecology of the Hawaiian crow, an endangered generalist. Condor 88, 211–219 (1986)

  22. 22.

    Seeking the Sacred Raven (Island Press, 2006)

  23. 23.

    & Activity profiles and hook-tool use of New Caledonian crows recorded by bird-borne video cameras. Biol. Lett. 11, 20150777 (2015)

  24. 24.

    , , , & (eds) Conservation Biology of Hawaiian Forest Birds (Yale Univ. Press, 2009)

  25. 25.

    , , & Non-tool-using rooks, Corvus frugilegus, solve the trap-tube problem. Anim. Cogn. 10, 225–231 (2007)

  26. 26.

    & Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part II. Passeriformes. Ornithol. Monogr. 46, 1–88 (1991)

  27. 27.

    The Descent of Man, and Selection in Relation to Sex (John Murray, 1871)

  28. 28.

    Tool-using and aimed throwing in a community of free-living chimpanzees. Nature 201, 1264–1266 (1964)

  29. 29.

    , , , & Effects of inbreeding and parental incubation on captive breeding success in Hawaiian crows. Biol. Conserv. 184, 357–364 (2015)

  30. 30.

    in Conservation Biology of Hawaiian Forest Birds (eds , , , & ) (Yale Univ. Press, 2009)

  31. 31.

    National Research Council (NRC). The Scientific Bases for the Preservation of the Hawaiian Crow (National Academy Press, 1992)

  32. 32.

    , , , & The influence of captive breeding management on founder representation and inbreeding in the ‘Alalaˉ, the Hawaiian crow. Conserv. Genet. 17, 369–378 (2016)

  33. 33.

    , , & A DNA test to sex most birds. Mol. Ecol. 7, 1071–1075 (1998)

  34. 34.

    , & Effects of early rearing experience on adult behavior and nesting in captive Hawaiian crows (Corvus hawaiiensis). Zoo Biol. 21, 59–75 (2002)

  35. 35.

    Solomon Coder (version beta14.03.10): A Simple Solution for Behavior Coding. (2011)

  36. 36.

    & An evaluation of the concept of innateness. Phil. Trans. R. Soc. B 366, 436–443 (2011)

  37. 37.

    , , & Artificial incubation and hand-rearing of ‘Alala (Corvus hawaiiensis) eggs removed from the wild. Zoo Biol. 13, 257–266 (1994)

  38. 38.

    , , & Seed dispersal by a captive corvid: the role of the ‘Alalaˉ (Corvus hawaiiensis) in shaping Hawai‘i’s plant communities. Ecol. Appl. 22, 1718–1732 (2012)

  39. 39.

    & Quantifying Behavior the JWatcher Way (Sinauer Associates, 2007)

  40. 40.

    R Development Core Team. R: A Language and Environment for Statistical Computing. (2014)

  41. 41.

    et al. Experimental resource pulses influence social-network dynamics and the potential for information flow in tool-using crows. Nat. Commun. 6, 7197 (2015)

  42. 42.

    et al. Social transmission of tool use and tool manufacture in Goffin cockatoos (Cacatua goffini). Proc. R. Soc. B 281, 20140972 (2014)

  43. 43.

    , , , & Social network analysis shows direct evidence for social transmission of tool use in wild chimpanzees. PLoS Biol. 12, e1001960 (2014)

  44. 44.

    , , & MTR: taxonomic annotation of short metagenomic reads using clustering at multiple taxonomic ranks. Bioinformatics 27, 196–203 (2011)

  45. 45.

    & Social Learning: An Introduction to Mechanisms, Methods and Models (Princeton Univ. Press, 2013)

  46. 46.

    , & Brains, tools, innovation and biogeography in crows and ravens. BMC Evol. Biol. 12, 72 (2012)

  47. 47.

    & MAFFT multiple sequence alignment software version 7: improvements in performance and usability. Mol. Biol. Evol. 30, 772–780 (2013)

  48. 48.

    & MRBAYES: Bayesian inference of phylogenetic trees. Bioinformatics 17, 754–755 (2001)

  49. 49.

    & Molecular systematics and biogeography of the Hawaiian avifauna. Stud. Avian Biol. 22, 51–60 (2001)

  50. 50.

    & Oscillating selection on Darwin’s finches. Nature 327, 511–513 (1987)

  51. 51.

    et al. Evolution of Darwin’s finches and their beaks revealed by genome sequencing. Nature 518, 371–375 (2015)

  52. 52.

    , , & The ecology of tool-use in the woodpecker finch (Cactospiza pallida). Ecol. Lett. 5, 656–664 (2002)

  53. 53.

    The use of tools by brown-headed nuthatches. Wilson Bull. 80, 220–224 (1968)

  54. 54.

    & in Tool Use in Animals: Cognition and Ecology (eds , & ) (Cambridge Univ. Press, 2013)

Download references


We thank: the many people – far too many to name individually – who have prevented the ‘Alalaˉ’s extinction, and who are working tirelessly towards its successful reintroduction into the wild; R. Fleischer for facilitating initial contacts; San Diego Zoo Global’s staff for assistance with experiments; C. Higgott for help with video scoring; D. Parker for constructing the consensus phylogeny; several photographers for providing images for Fig. 1; S. Thompson for help with graphic design; and G. Ruxton for statistical advice. Research was conducted with permission from San Diego Zoo Global’s IACUC animal welfare committee (Project ID#12-017), and with funding from the Biotechnology and Biological Sciences Research Council, UK (BBSRC; grant BB/G023913/2 to C.R., and studentship to B.C.K.), the University of St Andrews (C.R.), JASSO (S.S.), and the Royal Society of London (M.B.M.). Funding for the captive ‘Alala¯ propagation programme was provided by the U.S. Fish and Wildlife Service, Hawai‘i Division of Forestry and Wildlife, Moore Family Foundation, Marisla Foundation, several anonymous donors, and San Diego Zoo Global.

Author information


  1. Centre for Biological Diversity, School of Biology, University of St Andrews, Sir Harold Mitchell Building, St Andrews KY16 9TH, UK

    • Christian Rutz
    • , Barbara C. Klump
    • , Saskia Wischnewski
    • , Shoko Sugasawa
    • , Michael B. Morrissey
    •  & James J. H. St Clair
  2. Institute for Conservation Research, San Diego Zoo Global, PO Box 39, Volcano, Hawai‘i 96785, USA

    • Lisa Komarczyk
    • , Rosanna Leighton
    •  & Bryce M. Masuda
  3. Institute for Conservation Research, San Diego Zoo Global, 2375 Olinda Road, Makawao, Hawai‘i 96768, USA

    • Joshua Kramer
  4. Department of Physics and Centre for Networks and Collective Behaviour, University of Bath, Bath BA2 7AY, UK

    • Richard James
  5. Institute for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, California 92027, USA

    • Richard A. Switzer


  1. Search for Christian Rutz in:

  2. Search for Barbara C. Klump in:

  3. Search for Lisa Komarczyk in:

  4. Search for Rosanna Leighton in:

  5. Search for Joshua Kramer in:

  6. Search for Saskia Wischnewski in:

  7. Search for Shoko Sugasawa in:

  8. Search for Michael B. Morrissey in:

  9. Search for Richard James in:

  10. Search for James J. H. St Clair in:

  11. Search for Richard A. Switzer in:

  12. Search for Bryce M. Masuda in:


C.R. conceived of, initiated and led the project, and secured funding; R.A.S. and B.M.M. led the captive ‘Alalaˉ propagation programme, with support from R.L., J.K. and L.K.; C.R., J.J.H.S.C. and B.C.K. designed behavioural experiments; B.C.K., J.J.H.S.C. and C.R. conducted the species-wide tool-use assay, and L.K. performed the ontogeny experiment, with help from R.L., C.R., J.J.H.S.C. and B.C.K.; B.C.K. scored videos and extracted behavioural data, except for ontogeny trials, which were scored by S.W. and processed by S.S.; L.K., J.K., B.M.M. and C.R. collated and checked data on the life histories of captive birds; M.B.M. and B.C.K. assessed bird-performance data; R.J. and C.R. conducted social-diffusion simulations; C.R. and B.C.K. coordinated manuscript preparation, analysed data and prepared figures and videos; and C.R. wrote the manuscript, which was edited by B.C.K., J.J.H.S.C., R.J. and B.M.M., and approved by all co-authors.

Competing interests

The authors declare the following competing financial interests: five co-authors were (R.L., J.K., R.A.S.), or still are (L.K., B.M.M.), employees of San Diego Zoo Global, which is a not-for-profit organisation.

Corresponding author

Correspondence to Christian Rutz.

Reviewer Information Nature thanks T. Bugnyar, B. Kenward, S. Tebbich and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Extended data

Supplementary information


  1. 1.

    Spontaneous tool behaviour by an ‘Alalā

    This unedited scene shows the first presentation of the log set-up to adult male #134 (21 January 2013). Note that the log is a prototype that, compared to the final design later used for the species-wide behavioural assay, contained two additional holes.

  2. 2.

    Tool selectivity, modification and manufacture in ‘Alalā

    During experimental trials, many ‘Alalā were observed: a, to choose tools of appropriate dimensions; b, to replace tools that were not suitable; c, to transport non-supplied sticks to the set-up to be used as tools; to modify tools d, before or e, during deployment; or f, to handle, try and modify several different sticks during an extraction attempt. Tool manufacture behaviour included: g, snipping-off twigs from supplied dead branches; the production of h, bark flakes and i, wood splinters; and j, successive subtraction of material from non-supplied live plant material.

  3. 3.

    Ontogeny of tool-related behaviour in naïve juvenile ‘Alalā

    Functional tool behaviour can result from (a combination of) genetic predispositions, social learning, and individual learning. To investigate the relative importance of different processes, ‘naïve’ juveniles can be reared in captivity without opportunities to observe tool-use behaviour in proficient adult conspecifics, or even in humans. Under such controlled conditions, ‘Alalā chicks develop functional tool use over the first few months of life: a, first handling and carrying objects, including sticks, stones and other items; before b, inserting them into holes and crevices with gradually increasing proficiency (here, during a probe trial with several baited extraction tasks presented on a ‘platform’).

  4. 4.

    Historical recordings of ‘Alalā using tools

    Before the commencement of systematic behavioural experiments, staff at the KBCC and MBCC facilities had regularly observed ‘Alalā using tools. Following these opportunistic observations, on the 28 July 2011, four different birds were filmed using tools to reach for bait placed in a water bath (#114, #118, #135), or behind wire mesh (#146).

  5. 5.

    Eye movements in an ‘Alalā

    Like New Caledonian crows, ‘Alalā have unusually large eye-movement amplitudes. This video was taken when adult male #121 was trapped for a routine pre-breeding health check (19 March 2015) and presented with a neonate mouse to attract its attention.

  6. 6.

    Tool-use behaviour in crows

    Tool use of an adult male a, ‘Alalā and b, New Caledonian crow. ‘Alalā tend to hold stick tools in a frontal grip whereas New Caledonian crows prefer a transverse grip. c, Naturally non-tool-using rooks can be trained to use tools, but compared to most ‘Alalā and New Caledonian crows, they appear to handle sticks less dexterously (but note difference in extraction tasks provided).

About this article

Publication history






Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.