New Caledonian crows infer the weight of objects from observing their movements in a breeze

Sarah A. Jelbert, Rachael Miller*, Martina Schiestl, Markus Boeckle, Lucy G. Cheke, Russell D. Gray, Alex H. Taylor, Nicola S. Clayton

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

13 Citations (Scopus)

Abstract

Humans use a variety of cues to infer an object's weight, including how easily objects can be moved. For example, if we observe an object being blown down the street by the wind, we can infer that it is light. Here, we tested whether New Caledonian crows make this type of inference. After training that only one type of object (either light or heavy) was rewarded when dropped into a food dispenser, birds observed pairs of novel objects (one light and one heavy) suspended from strings in front of an electric fan. The fan was either on-creating a breeze which buffeted the light, but not the heavy, object-or off, leaving both objects stationary. In subsequent test trials, birds could drop one, or both, of the novel objects into the food dispenser. Despite having no opportunity to handle these objects prior to testing, birds touched the correct object (light or heavy) first in 73% of experimental trials, and were at chance in control trials. Our results suggest that birds used pre-existing knowledge about the behaviour exhibited by differently weighted objects in the wind to infer their weight, using this information to guide their choices.

Original languageEnglish
Article number2332
JournalProceedings of the Royal Society B: Biological Sciences
Volume286
Issue number1894
DOIs
Publication statusPublished - 16 Jan 2019

Keywords

  • Causal reasoning
  • Corvid cognition
  • Motion
  • Object properties
  • Observational learning

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