title: Discovery of species-wide tool use in the Hawaiian crow.
abstract: Only a handful of bird species are known to use foraging tools in the wild. Amongst them, the New Caledonian crow (Corvus moneduloides) stands out with its sophisticated tool-making skills. 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 comparisons. 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 captivity, 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 related, 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 risk. 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.
authors.affiliation: Centre for Biological Diversity, School of Biology, University of St Andrews, Sir Harold Mitchell Building, St Andrews KY16 9TH, UK.
authors.forename: Christian
authors.initials: C
authors.lastname: Rutz
authors.affiliation: Centre for Biological Diversity, School of Biology, University of St Andrews, Sir Harold Mitchell Building, St Andrews KY16 9TH, UK.
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Klump
authors.affiliation: Institute for Conservation Research, San Diego Zoo Global, PO Box 39, Volcano, Hawai'i 96785, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Komarczyk
authors.affiliation: Institute for Conservation Research, San Diego Zoo Global, PO Box 39, Volcano, Hawai'i 96785, USA.
authors.forename: Rosanna
authors.initials: R
authors.lastname: Leighton
authors.affiliation: Institute for Conservation Research, San Diego Zoo Global, 2375 Olinda Road, Makawao, Hawai'i 96768, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Kramer
authors.affiliation: Centre for Biological Diversity, School of Biology, University of St Andrews, Sir Harold Mitchell Building, St Andrews KY16 9TH, UK.
authors.forename: Saskia
authors.initials: S
authors.lastname: Wischnewski
authors.affiliation: Centre for Biological Diversity, School of Biology, University of St Andrews, Sir Harold Mitchell Building, St Andrews KY16 9TH, UK.
authors.forename: Shoko
authors.initials: S
authors.lastname: Sugasawa
authors.affiliation: Centre for Biological Diversity, School of Biology, University of St Andrews, Sir Harold Mitchell Building, St Andrews KY16 9TH, UK.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Morrissey
authors.affiliation: Department of Physics and Centre for Networks and Collective Behaviour, University of Bath, Bath BA2 7AY, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: James
authors.affiliation: Centre for Biological Diversity, School of Biology, University of St Andrews, Sir Harold Mitchell Building, St Andrews KY16 9TH, UK.
authors.forename: James J H
authors.initials: JJ
authors.lastname: St Clair
authors.affiliation: Institute for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, California 92027, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Switzer
authors.affiliation: Institute for Conservation Research, San Diego Zoo Global, PO Box 39, Volcano, Hawai'i 96785, USA.
authors.forename: Bryce M
authors.initials: BM
authors.lastname: Masuda
mesh_terms: D000375:Aging; D000818:Animals; D000836:Animals, Zoo / Q000502:physiology; D005075:Biological Evolution; D003071:Cognition; D046368:Crows / Q000145:classification / Q000502:physiology*; D005260:Female; D006254:Hawaii; D008297:Male; D010802:Phylogeny; D013045:Species Specificity; D053001:Tool Use Behavior