Reasoning, Physical & Social Cognition in New Caledonian crows

Abstract

New Caledonian crows are an exceptional species of bird, known to manufacture and use complex tools in the wild. In captivity, they appear to possess a causal understanding of many elements of tool use and to demonstrate a number of advanced cognitive abilities. As a member of the large-brained corvid family, these birds have been collectively referred to as ‘feathered apes’. However, to what extent are the cognitive abilities of New Caledonian crows similar to those of the great apes? Is it the case that these crows possess a suite of generalised cognitive abilities, comparable in breadth and flexibility to those of our closest primate relatives? Or, alternatively, have these birds evolved more specialised cognitive adaptions, perhaps in response to the evolutionary pressures of tool manufacture and use? In this thesis, I investigate the cognitive abilities of New Caledonian crows across a broad range of domains. I report the results of five experimental studies designed to tap different aspects of New Caledonian crow cognition, spanning the fields of causal reasoning, reasoning by exclusion, cooperation, self-control, and the cultural transmission of tool designs. From the results of this work I argue that New Caledonian crows could be characterised as possessing a portfolio of advanced physical cognition and reasoning abilities, but more limited social cognition. This body of work therefore highlights a number of similarities, but also a number of differences, between the cognitive abilities of New Caledonian crows and the great apes, and provides a window into the ways in which intelligence evolves.