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	Author	Reboreda, J.C.; Clayton, N.S.; Kacelnik, A.
	Title	Species and sex differences in hippocampus size in parasitic and non-parasitic cowbirds			Type	Journal Article
	Year	1996	Publication	Neuroreport	Abbreviated Journal	Neuroreport
	Volume	7	Issue	2	Pages	505-508
	Keywords	Animals; Birds/physiology; Female; Hippocampus/anatomy & histology; Male; Nesting Behavior/*physiology; Sex Characteristics; Species Specificity; Telencephalon/anatomy & histology
	Abstract	To test the hypothesis that selection for spatial abilities which require birds to locate and to return accurately to host nests has produced an enlarged hippocampus in brood parasites, three species of cowbird were compared. In shiny cowbirds, females search for host nests without the assistance of the male; in screaming cowbirds, males and females inspect hosts' nests together; in bay-winged cowbirds, neither sex searches because this species is not a brood parasite. As predicted, the two parasitic species had a relatively larger hippocampus than the non-parasitic species. There were no sex differences in relative hippocampus size in screaming or bay-winged cowbirds, but female shiny cowbirds had a larger hippocampus than the male.
	Address	Instituto de Biologia y Medicina Experimental-CONICET, Buenos Aires, Argentina
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0959-4965	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:8730816			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	4798
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	Author	Astié, A.A.; Kacelnik, A.; Reboreda, J.C.
	Title	Sexual differences in memory in shiny cowbirds			Type	Journal Article
	Year	1998	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	1	Issue	2	Pages	77-82
	Keywords
	Abstract	Avian brood parasites depend on other species, the hosts, to raise their offspring. During the breeding season, parasitic cowbirds (Molothrus sp.) search for potential host nests to which they return for laying a few days after first locating them. Parasitic cowbirds have a larger hippocampus/telencephalon volume than non-parasitic species; this volume is larger in the sex involved in nest searching (females) and it is also larger in the breeding than in the non-breeding season. In nature, female shiny cowbirds Molothrus bonariensis search for nests without the male's assistance. Here we test whether, in association with these neuroanatomical and behavioural differences, shiny cowbirds display sexual differences in a memory task in the laboratory. We used a task consisting of finding food whose location was indicated either by the appearance or the location of a covering disk. Females learnt to retrieve food faster than males when food was associated with appearance cues, but we found no sexual differences when food was associated with a specific location. Our results are consistent with the view that parasitism and its neuroanatomical correlates affect performance in memory tasks, but the effects we found were not in the expected direction, emphasising that the nature of avian hippocampal function and its sexual differences are not yet understood.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	3158
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	Author	Weir, A.A.S.; Chappell, J.; Kacelnik, A.
	Title	Shaping of hooks in New Caledonian crows			Type	Journal Article
	Year	2002	Publication	Science (New York, N.Y.)	Abbreviated Journal	Science
	Volume	297	Issue	5583	Pages	981
	Keywords	Animals; Behavior, Animal; Cognition; Female; Male; Songbirds/*physiology
	Abstract
	Address	Department of Zoology, South Parks Road, Oxford OX1 3PS, UK
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1095-9203	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12169726			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	2842
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	Author	Chappell, J.; Kacelnik, A.
	Title	Tool selectivity in a non-primate, the New Caledonian crow (Corvus moneduloides)			Type	Journal Article
	Year	2002	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	5	Issue	2	Pages	71-78
	Keywords	Adaptation, Psychological; Animals; Cognition; Female; Learning; Male; Perception; *Songbirds
	Abstract	We present an experiment showing that New Caledonian crows are able to choose tools of the appropriate size for a novel task, without trial-and-error learning. This species is almost unique amongst all animal species (together with a few primates) in the degree of use and manufacture of polymorphic tools in the wild. However, until now, the flexibility of their tool use has not been tested. Flexibility, including the ability to select an appropriate tool for a task, is considered to be a hallmark of complex cognitive adaptations for tool use. In experiment 1, we tested the ability of two captive birds (one male, one female), to select a stick (from a range of lengths provided) matching the distance to food placed in a horizontal transparent pipe. Both birds chose tools matching the distance to their target significantly more often than would be expected by chance. In experiment 2, we used a similar task, but with the tools placed out of sight of the food pipe, such that the birds had to remember the distance of the food before selecting a tool. The task was completed only by the male, who chose a tool of sufficient length significantly more often than chance but did not show a preference for a matching length.
	Address	Department of Zoology, University of Oxford, South Parks Road, Oxford OXI 3PS, UK. jackie.chappell@zoo.ox.ac.uk
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1435-9448	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:12150038			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	2606
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	Author	Chappell, J.; Kacelnik, A.
	Title	Selection of tool diameter by New Caledonian crows Corvus moneduloides			Type	Journal Article
	Year	2004	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	7	Issue	2	Pages	121-127
	Keywords	Animals; Behavior, Animal; Choice Behavior; Discrimination Learning; Feeding Behavior; Female; Functional Laterality; Manufactured Materials; Plant Leaves; Problem Solving; Songbirds; Technology
	Abstract	One important element of complex and flexible tool use, particularly where tool manufacture is involved, is the ability to select or manufacture appropriate tools anticipating the needs of any given task-an ability that has been rarely tested in non-primates. We examine aspects of this ability in New Caledonian crows-a species known to be extraordinary tool users and manufacturers. In a 2002 study, Chappell and Kacelnik showed that these crows were able to select a tool of the appropriate length for a task among a set of different lengths, and in 2002, Weir, Chappell and Kacelnik showed that New Caledonian crows were able to shape unfamiliar materials to create a usable tool for a specific task. Here we examine their handling of tool diameter. In experiment 1, we show that when facing three loose sticks that were usable as tools, they preferred the thinnest one. When the three sticks were presented so that one was loose and the other two in a bundle, they only disassembled the bundle when their preferred tool was tied. In experiment 2, we show that they manufacture, and modify during use, a tool of a suitable diameter from a tree branch, according to the diameter of the hole through which the tool will have to be inserted. These results add to the developing picture of New Caledonian crows as sophisticated tool users and manufacturers, having an advanced level of folk physics.
	Address	Department of Zoology, South Parks Road, OX1 3PS, Oxford, UK. jackie.chappell@zoo.ox.ac.uk
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1435-9448	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:15069612			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	2528
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	Author	Weir, A.A.S.; Kacelnik, A.
	Title	A New Caledonian crow (Corvus moneduloides) creatively re-designs tools by bending or unbending aluminium strips			Type	Journal Article
	Year	2006	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	9	Issue	4	Pages	317-334
	Keywords	Animals; Comprehension; Crows; Female; Learning; Motor Skills; Problem Solving; *Tool Use Behavior
	Abstract	Previous observations of a New Caledonian crow (Corvus moneduloides) spontaneously bending wire and using it as a hook [Weir et al. (2002) Science 297:981] have prompted questions about the extent to which these animals 'understand' the physical causality involved in how hooks work and how to make them. To approach this issue we examine how the same subject (“Betty”) performed in three experiments with novel material, which needed to be either bent or unbent in order to function to retrieve food. These tasks exclude the possibility of success by repetition of patterns of movement similar to those employed before. Betty quickly developed novel techniques to bend the material, and appropriately modified it on four of five trials when unbending was required. She did not mechanically apply a previously learned set of movements to the new situations, and instead sought new solutions to each problem. However, the details of her behaviour preclude concluding definitely that she understood and planned her actions: in some cases she probed with the unmodified tools before modifying them, or attempted to use the unmodified (unsuitable) end of the tool after modification. Gauging New Caledonian crows' level of understanding is not yet possible, but the observed behaviour is consistent with a partial understanding of physical tasks at a level that exceeds that previously attained by any other non-human subject, including apes.
	Address	Department of Zoology, South Parks Road, Oxford, OX1 3PS, UK. alex.weir@magdalen.oxon.org
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1435-9448	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:17024509			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	2436
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	Author	Brunner, D.; Kacelnik, A.; Gibbon, J.
	Title	Memory for inter-reinforcement interval variability and patch departure decisions in the starling,Sturnus vulgaris			Type	Journal Article
	Year	1996	Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	51	Issue	5	Pages	1025-1045
	Keywords
	Abstract	An experiment with starlings was conducted to investigate the effect of variability in inter-reinforcement intervals on foraging decisions. The experimental design simulated an environment in which food was distributed in patches. Patches contained zero to four food items which could be collected by pecking at a key. All patches ended with sudden depletion. The time elapsed since the last reinforcement was the only way to detect the depletion of the patch. Once a patch was depleted, a new patch could be reached by completion of a travel requirement of 20 flights between two perches. Key pecks within a patch and the time of the last response in a patch (giving-in time) were recorded. The level of variability in the inter-reinforcement intervals was varied between different conditions. An increase in inter-reinforcement interval variability resulted in a flattening of response rate functions and giving-in time distributions, and in more asymmetry of the response functions, but not of the giving-in time distributions. Two theoretical models of decision making are presented, which differ in the assumptions about memory constraints. In one case, all inter-reinforcement intervals are remembered but in the other, only the intervals with extreme values are remembered. Both models accommodate response rates as a function of trial time, but only the second is compatible with the observed departure decision. Our results are compatible with net rate maximization.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	2109
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	Author	Kacelnik, A.; Todd, I.A.
	Title	Psychological mechanisms and the Marginal Value Theorem: effect of variability in travel time on patch exploitation			Type	Journal Article
	Year	1992	Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	43	Issue	2	Pages	313-322
	Keywords
	Abstract	The Marginal Value Theorem (MVT) describes the behaviour that maximizes the ratio of expected gain over expected foraging time in a patchy environment. When travel time is variable, the MVT rationale and its predictions are sensitive only to the mean travel time and not to the spread or skew of the distribution. Two mechanistic arguments contradict these predictions. First, tests of the MVT have previously shown that there is a disproportionate influence of the last travel time, and second, psychological models of information processing suggest that memory for time intervals is strongly dependent on the scatter of the distribution experienced. These mechanistic concepts, combined with Jensen's inequality, suggest that patch exploitation should decrease as the scatter of the travel distribution increases. In a Skinner box experiment with pigeons, Columba livia, the problem was examined by simulating three environments with identical patches and the same mean travel time, but different travel time variability. Patch exploitation decreased with increasing variance in travel time. The results are used to argue in favour of the inclusion of realistic psychological properties as constraints in functional models of behaviour. Although both the MVT and the mechanistic models account for some features of the results, none of them can explain all the findings.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	2114
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	Author	Kacelnik, A.; Marsh, B.
	Title	Cost can increase preference in starlings			Type	Journal Article
	Year	2002	Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	63	Issue	2	Pages	245-250
	Keywords
	Abstract	We used European starlings, Sturnus vulgaris, to investigate the relationship between the cost paid to obtain food rewards and preference between stimuli associated with the resulting rewards. In no-choice trials either 16 1-m flights (high effort) or four 1-m flights (low effort) gave access to differently coloured keys. Pecking at these keys resulted in identical food rewards. When subjects were given choices between the coloured keys in choice trials without having paid any effort, the majority preferred the coloured key that was paired with the higher level of work in no-choice trials. We relate our findings to results in animal behaviour, psychology and economics, and give a theoretical account that has implications for phenomena variously recognized as the `sunk cost fallacy' (the tendency to invest more in something after much has already been invested), `work ethics' (valuing an option more as a result of physical effort), `cognitive dissonance' (making mental effort to overlook or re-evaluate information that does not accord with a dominant internal representation) and the `Concorde Fallacy' (the readiness to forego more fitness for something that has been responsible for greater fitness compromise in the past).
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	2107
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	Author	Kacelnik, A.; Houston, A.I.
	Title	Some effects of energy costs on foraging strategies			Type	Journal Article
	Year	1984	Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	32	Issue	2	Pages	609-614
	Keywords
	Abstract	We consider the effect of including energy costs on the optimal strategy for animals exploiting a depleting food resource. In the context of central place foraging this leads to the problem of what load size should be brought back to the central place. Two strategies are discussed: (i) maximize gross rate of energy delivery and (ii) maximize net rate of energy delivery. The optimal load size (or optimal patch time) for net maximizers is not always larger than for gross maximizers, as has been claimed. Instead, the difference in optimal load size has the same sign as the difference between metabolic rates of travelling and foraging. We point out that the influence of costs has not always been correctly incorporated in experimental tests of the theory.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	2122
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