The ecological significance of tool use in New Caledonian crows.
Tool use is so rare in the animal kingdom that its evolutionary origins cannot be traced with comparative analyses. Valuable insights can be gained from investigating the ecological context and adaptive significance of tool use under contemporary conditions, but obtaining robust observational data is challenging. We assayed individual-level tool-use dependence in wild New Caledonian crows by analyzing stable isotope profiles of the birds' feathers, blood, and putative food sources. Bayesian diet-mixing models revealed that a substantial amount of the crows' protein and lipid intake comes from prey obtained with stick tools--wood-boring beetle larvae. Our calculations provide estimates of larva-intake rates and show that just a few larvae can satisfy a crow's daily energy requirements, highlighting the substantial rewards available to competent tool users.
Rutz
Christian
C
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK. christian.rutz@zoo.ox.ac.uk
Bluff
Lucas A
LA
Reed
Nicola
N
Troscianko
Jolyon
J
Newton
Jason
J
Inger
Richard
R
Kacelnik
Alex
A
Bearhop
Stuart
S
D031284:Aleurites; D000818:Animals; D001499:Bayes Theorem; D002247:Carbon Isotopes / Q000032:analysis / Q000097:blood; D001517:Coleoptera; D046368:Crows / Q000502:physiology*; D004032:Diet; D005241:Feathers / Q000737:chemistry; D005247:Feeding Behavior; D005260:Female; D007814:Larva; D008297:Male; D009510:New Caledonia; D009587:Nitrogen Isotopes / Q000032:analysis / Q000097:blood; D009754:Nuts; D053001:Tool Use Behavior
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes