Insightful problem solving and creative tool modification by captive nontool-using rooks

Abstract

The ability to use tools has been suggested to indicate advanced physical cognition in animals. Here we show that rooks, a member of the corvid family that do not appear to use tools in the wild are capable of insightful problem solving related to sophisticated tool use, including spontaneously modifying and using a variety of tools, shaping hooks out of wire, and using a series of tools in a sequence to gain a reward. It is remarkable that a species that does not use tools in the wild appears to possess an understanding of tools rivaling habitual tool users such as New Caledonian crows and chimpanzees. Our findings suggest that the ability to represent tools may be a domain-general cognitive capacity rather than an adaptive specialization and questions the relationship between physical intelligence and wild tool use.cognition ͉ intelligence ͉ Corvus ͉ frugilegus ͉ hook

Extreme binocular vision and a straight bill facilitate tool use in New Caledonian crows

“…Curved bills are thought to assist the visual inspection of the contents of the open bill in crow species probing in the ground or in carcasses 12,13 , suggesting that the NC crow has forgone this ability in favour of a bill shape that is suited to gripping and visually guiding tools. The rook C. frugilegus, a species that does not habitually use tools in the wild, has recently been shown to be a capable tool user in captivity 14 . Interestingly, our comparative results show that the rooks' ability to see along a tool is better than that of other nontool-using crows, as a consequence of its moderate bill curvature (compare Figs 1 and 5).…”

“…Interestingly, our comparative results show that the rooks' ability to see along a tool is better than that of other nontool-using crows, as a consequence of its moderate bill curvature (compare Figs 1 and 5). However, we note that the rooks used in earlier experiments 14 extracted bait from a transparent apparatus, so the limitations of their visual field could not be assessed. We suggest that future work further explores the envelope of conceivable tool grips, and resulting tool-projection angles, and cross-validates results with captive birds.…”

If at first you don't succeed… Studies of ontogeny shed light on the cognitive demands of habitual tool use

“…Nevertheless, it is clear that it is within the capability of these species to solve new problems involving unfamiliar materials and using novel behavioural sequences. One point to note is that to date there has been no evidence that tool users outperform non-tool-using relatives in the arena of innovation or problem-solving involving tools (see [93] and [94] for examples of innovation and sequential tool use in non-tool-using rooks). Interestingly, performance in these studies is often characterized by large individual differences, with some experiments showing a minority of individuals completing the most difficult conditions [89,95,96].…”

Corvids create novel causal interventions after all

“…Most importantly, one rook was able to drop a stone into the apparatus on her first trial, after having only observed her mate nudge and then drop stones and having never experienced the required actions or objects beforehand [3]. This meets Taylor et al's [1] conditions for causal intervention by observation.…”

“…B 282: 20142504 whether or not the effect is caused accidentally, except for more detailed interpretations that involve elements such as the structure and explicitness of causal representations [4]. By contrast, the rook that immediately dropped stones after observing her mate seems to be an agent causal learner [3].…”