Award details

Social and developmental cognition of caching by Western Scrub-Jays

Reference	BB/D000335/1
Principal Investigator / Supervisor	Professor Nicola Clayton
Co-Investigators / Co-Supervisors	Dr Selvino de Kort, Professor Anthony Dickinson, Dr Nathan Emery
Institution	University of Cambridge
Department	Psychology
Funding type	Research
Value (£)	375,859
Status	Completed
Type	Research Grant
Start date	01/09/2005
End date	31/08/2008
Duration	36 months

Abstract

Recent research suggests that corvids have cognitive capacities comparable to those of the great apes. For instance, food-storing scrub-jays show the behavioural components of retrospective and prospective cognition (Mental Time Travel), a trait thought to be uniquely human. In addition, when observed by another jay during food-caching scrub-jays show various behavioural strategies that appear to minimize cache pilfering by an observer. Jays preferentially cache food behind barriers, in shady sites instead of well-lit locations, and at a distance from an observer, but they only do so when observed by another bird. Furthermore, when returning to their cache sites, jays may re-hide their food caches in new locations, but again only if they were observed during the initial caching episode and, importantly, only when they themselves had experience of pilfering other individuals' caches. These cache-protection strategies, and especially the apparent experience-projection in re-caching, suggest that caching may be controlled by complex socio-cognitive processes that bear some similarity to the human capacity for 'Theory of Mind'. Within this framework, the overall aim of thisproject is to determine the nature and development of the cognitive processes mediating caching and cache-protection strategies. The demonstration of a role for complex social cognition in food-caching by scrub-jays would have important implications for our understanding of the general evolution of complex social cognition, because this capacity would have to have evolved independently, and hence convergently, in apes and corvids. High-level corvid cognition would thus challenge the commonly held belief that complex cognition evolved only once. Specifically, we shall test whether these cache-protection behaviours are sensitive to their consequences and study the role of different forms of social cognition. The initial experiments adopt a functional approach by testing whether the implementation of the cache-protection strategies is modulated by the consequences at recovery in terms of the probability that caches might be stolen. A second set of experiments will focus on experience projection and knowledge attribution. A cognitive interpretation of re-caching behaviour assumes that cachers with previous experience of being a thief use this information to predict the behaviour of a potential pilferer, and that they should also attribute knowledge of the location of the caches to a particular observer. We shall investigate this hypothesis by studying the induction of re-caching by the presence of knowledgeable and ignorant observers, and the extent to which such behaviour depends upon experience of being a thief and having one's caches pilfered. Mental time travel and mental attribution are inextricably linked in human cognition and develop around the same, relative late age in children. As little is known about the development of caching and recovery in scrub-jays, we shall examine the basic developmental trajectory of caching and recovery and relate it to the development of object permanence. Once basic caching and recovery is established, we shall investigate the development of control over both caching and recovery by general and socio-cognitive processes. The experiments will be conducted using a well-established caching-recovery paradigm in which the birds cache different foods, such as peanuts or wax worms, in trial-unique caching trays. A specially designed set of housing cages allows us to carefully control the social interactions between birds during caching and recovery. For the development studies, we shall hand-raise a new group of scrub-jays so that we shall be able to carefully control their experience with caching and recovery.

Summary

The last 20 years have seen a major revolution in our understanding of animal intelligence, the ability to think, reason and solve novel problems. As humans, our thoughts are not 'stuck in time' because we can think about our past, and plan for our future (Mental Time Travel). We can also reason about what others might be thinking (Theory of Mind) and we can devise novel solutions to problems, such as the manufacture of special tools to acquire otherwise unobtainable foods. It has been known for many years that some monkeys and apes share some of these abilities with us. Given that they are our closest animal relatives perhaps this is not surprising. However, recent findings suggest that some, if not all, of these intellectual abilities are present within other, much more distant relatives, namely crows and parrots. It has been argued that members of the crow family, which include the ravens and the jays, have cognitive capacities comparable to those of great apes. This wider distribution of intelligence has two important implications, one practical and one theoretical. The first concerns the welfare of animals. The realization that these birds are as clever as apes has significant implications for the procedures used to control wild populations of these birds, as well as the way in which crows are housed in captivity. The second issue relates to whether or not intelligence requires a large mammalian brain. Most of the research has focused primarily on the large-brained social apes because of their close evolutionary relationship to humans, and the common assumption that intelligence evolved only once. The finding that some birds are also intelligent challenges this assumption because the common ancestor of mammals and birds lived over 280 million years ago and not all birds and mammals share the complex intellectual abilities found in crows and apes. Consequently, the existence of complex cognitive abilities in these two distantly related groups of animals must have arisen independently. Furthermore, the bird brain has a very different structure to that of all mammals. So this conclusion, if substantiated, challenges the widespread assumption that the ape brain is a necessary platform for intelligence. Food-caching behaviour is ideal for research on animal intelligence because it involoves many complex cognitive processes. Birds have to remember which foods they cached where and how long ago they stored it. They also steal each other's food caches and we have discovered that scrub-jays go to great lengths to prevent other birds from stealing their caches. For instance they hide their food behind objects or in shady places as opposed to well-lit places in order to make it more difficult for potential thiefs to observe where the food is hidden. If the jays are watched during caching, they will return to their caches later and rehide them in new places, unbeknown to the observer. These strategies seem to suggest that the jays know what other birds know (knowledge attribution), which up till recently was thought to be a capacity reserved for apes. Although food caching behaviour is hard-wired, the strategies used to reduce pilferage of caches seem to depend on experience. Similar capacities in humans develop only after the age of 4. To assess whether these capacities are indeed similar in birds and apes, it is necessary to investigate whether they also develop in similar ways in apes and birds. Our research thus also aims to gain insight in how scrub-jays learn to protect their caches.

Committee	Closed Committee - Animal Sciences (AS)
Research Topics	Neuroscience and Behaviour
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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