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	Author	Bugnyar, T.; Heinrich, B.
	Title	Pilfering ravens, Corvus corax, adjust their behaviour to social context and identity of competitors			Type	Journal Article
	Year	2006	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	9	Issue	4	Pages	369-376
	Keywords	Adaptation, Psychological; Animals; Behavior, Animal; Competitive Behavior; Crows/physiology; Deception; Feeding Behavior; Female; Male; Social Behavior; *Social Environment
	Abstract	Like other corvids, food-storing ravens protect their caches from being pilfered by conspecifics by means of aggression and by re-caching. In the wild and in captivity, potential pilferers rarely approach caches until the storers have left the cache vicinity. When storers are experimentally prevented from leaving, pilferers first search at places other than the cache sites. These behaviours raise the possibility that ravens are capable of withholding intentions and providing false information to avoid provoking the storers' aggression for cache protection. Alternatively, birds may refrain from pilfering to avoid conflicts with dominants. Here we examined whether ravens adjust their pilfer tactics according to social context and type of competitors. We allowed birds that had witnessed a conspecific making caches to pilfer those caches either in private, together with the storer, or together with a conspecific bystander that had not created the caches (non-storer) but had seen them being made. Compared to in-private trials, ravens delayed approaching the caches only in the presence of storers. Furthermore, they quickly engaged in searching away from the caches when together with dominant storers but directly approached the caches when together with dominant non-storers. These findings demonstrate that ravens selectively alter their pilfer behaviour with those individuals that are likely to defend the caches (storers) and support the interpretation that they are deceptively manipulating the others' behaviour.
	Address	Department of Biology, University of Vermont, Burlington, VT 05405, USA. thomas.bugnyar@univie.ac.at
	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:16909235			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	2449
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	Author	Bugnyar, T.; Kotrschal, K.
	Title	Observational learning and the raiding of food caches in ravens, Corvus corax: is it `tactical' deception?			Type	Journal Article
	Year	2002	Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	64	Issue	2	Pages	185-195
	Keywords
	Abstract	Group-foraging ravens scatter-hoard when they are competing for food and, to some extent, also raid the caches made by others. We investigated the effects of observational spatial memory on individual caching and raiding tactics. With captive ravens, we found visual observation was essential for locating and raiding the caches of conspecifics. Both captive and free-ranging ravens, food cachers as well as potential cache raiders, responded to each other's presence. Cachers withdrew from conspecifics and most often placed their caches behind structures, obstructing the view of potential observers. Raiders watched inconspicuously and kept at a distance to cachers close to their cache sites. In response to the presence of potential raiders or because of their initial movements towards caches, the cachers frequently interrupted caching, changed cache sites, or recovered their food items. These results suggest that ravens, regardless of whether they act as cachers or raiders, are capable of withholding information about their intentions and, hence, manipulate the other bird's attention either to prevent or to achieve social-learning opportunities. Such interactions may qualify as `tactical' deception and may have created a considerable pressure selecting for social cognition in ravens. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.
	Address
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	Series Volume		Series Issue		Edition
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	Notes				Approved	no
	Call Number	Equine Behaviour @ team @			Serial	2904
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	Author	Heinrich, B.; Bugnyar, T.
	Title	Just how smart are ravens?			Type	Journal Article
	Year	2007	Publication	Scientific American	Abbreviated Journal	Sci Am
	Volume	296	Issue	4	Pages	64-71
	Keywords	Animals; Behavior, Animal; Crows/physiology; Environment; *Intelligence; Predatory Behavior; Problem Solving; Thinking
	Abstract
	Address	University of Vermont, USA
	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	0036-8733	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:17479632			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	4101
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	Author	Range, F.; Bugnyar, T.; Schlogl, C.; Kotrschal, K.
	Title	Individual and sex differences in learning abilities of ravens			Type	Journal Article
	Year	2006	Publication	Behavioural Processes	Abbreviated Journal	Behav. Process.
	Volume	73	Issue	1	Pages	100-106
	Keywords	Animals; Behavior, Animal/physiology; Crows; Discrimination Learning/physiology; Exploratory Behavior/physiology; Female; Individuality; Male; Sex Factors; Spatial Behavior
	Abstract	Behavioral and physiological characteristics of individuals within the same species have been found to be stable across time and contexts. In this study, we investigated individual differences in learning abilities and object and social manipulation to test for consistency within individuals across different tasks. Individual ravens (Corvus corax) were tested in simple color and position discrimination tasks to establish their learning abilities. We found that males were significantly better in the acquisition of the first discrimination task and the object manipulation task, but not in any of the other tasks. Furthermore, faster learners engaged less often in manipulations of conspecifics and exploration of objects to get access to food. No relationship between object and social manipulation and reversal training were found. Our results suggest that individual differences in regard to the acquisition of new tasks may be related to personalities or at least object manipulation in ravens.
	Address	Konrad Lorenz Research Station, A-4645 Gruenau 11, Austria. friederike.range@univie.ac.at
	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	0376-6357	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:16675158			Approved	no
	Call Number	Equine Behaviour @ team @			Serial	4146
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	Author	Bugnyar, T.; Kotrschal, K.
	Title	*Leading a conspecific away from food in ravens ( Corvus corax)?*			Type	Journal Article
	Year	2004	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	7	Issue	2	Pages	69-76
	Keywords	Misleading – Deception – Raven – Social foraging
	Abstract	Active misleading of conspecifics has been described as a social strategy mainly for primates. Here we report a raven leading a competitor away from food in a social foraging task. Four individuals had to search and compete for hidden food at color-marked clusters of artificial food caches. At the beginning of the experiment, a subordinate male found and exploited the majority of the food. As a result, the dominant male displaced him from the already opened boxes. The subordinate male then developed a pattern, when the loss of reward to the dominant got high, of moving to unrewarded clusters and opening boxes there. This diversion often led the dominant to approach those unrewarded clusters and the subordinate then had a head start for exploiting the rewarded boxes. Subsequently, however, the dominant male learned not to follow the subordinate to unrewarded clusters and eventually started searching for the reward himself. These interactions between the two males illustrate the ravens' potential for deceptively manipulating conspecifics. We discuss under which circumstances ravens might use this capacity.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
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	Series Volume		Series Issue		Edition
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	Notes				Approved	no
	Call Number				Serial	2080
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	Author	Bugnyar, T.; Kotrschal, K.
	Title	*Movement coordination and signalling in ravens (Corvus corax): an experimental field study*			Type	Journal Article
	Year	2001	Publication	Acta ethologica	Abbreviated Journal	Acta. Ethol.
	Volume	3	Issue	2	Pages	101-109
	Keywords	Ravens – Corvus corax – Foraging – Coordination – Communication
	Abstract	Vagrant non-breeding ravens frequently attract conspecifics to rich ephemeral food sources. There, grouping may allow them to overcome the defence of territorial breeders. Here, we focus on ravens making use of regular food supplies in a game park, where they divert food from the provision of park animals. We investigated if ravens foraging in the Cumberland game park (Grünau, Austria) are attentive towards one another when they experience some unpredictability in food provisioning. We confronted a group of 30-50 ravens with two different treatments. Ten minutes ahead of the feeding of either wolves or wild boars we showed buckets containing pieces of meat to the ravens flying overhead. In the reliable cue treatment (RCT), the meat was placed next to one of the two enclosures, whereas in the unreliable cue treatment (UCT), the buckets were placed simultaneously in front of both enclosures though only in one of the enclosures were the animals fed 10 min later. Thus, during RCT but not during UCT, ravens could predict where food would become available. Only during UCT, ravens moved in large groups between the two feeding sites. Many ravens moving at the same time in the same direction may indicate some co-ordination in space and time, which is most likely achieved by social attraction among individuals. Furthermore, the number of ravens approaching and leaving, respectively, a feeding site cross-correlated with a temporary increase in the rate of a food-associated call, the yell. This suggests that in addition to watching each other, calling may have contributed to group formation. Possible benefits of group formation during food inspection are discussed.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Summary Language		Original Title
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	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	2081
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	Author	Schloegl, C.; Kotrschal, K.; Bugnyar, T.
	Title	Gaze following in common ravens, Corvus corax: ontogeny and habituation			Type	Journal Article
	Year	2007	Publication	Animal Behaviour.	Abbreviated Journal	Anim. Behav.
	Volume	74	Issue	4	Pages	769-778
	Keywords	Corvus corax; gaze following; habituation; ontogenetic development; raven
	Abstract	Co-orientation with others by using their gaze direction is considered to be adaptive for detecting food or predators or monitoring social interactions. Like the great apes, common ravens are capable of following human experimenters' gaze direction not only into distant space but also behind visual barriers. We investigated the ontogenetic development of these abilities by confronting birds with a human foster parent looking up (experiment 1) and behind visual barriers (experiment 3) and their modification by habituation (experiments 2 and 4). We tested a group of 12 hand-reared ravens during their first 10 months of life. Ravens responded to others' look-ups soon after fledging but could track their gaze behind a visual barrier only 4 months later, at the age they usually become independent from their parents. Furthermore, ravens quickly ceased responding to repeated look-ups by the model, but did not habituate to repeated gaze cues directed behind a barrier. Our findings support the idea that the two modes of gaze following reflect different cognitive levels in ravens and, possibly, have different functions.
	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	4204
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	Author	Schloegl, C.; Kotrschal, K.; Bugnyar, T.
	Title	Modifying the object-choice task: Is the way you look important for ravens?			Type	Journal Article
	Year	2008	Publication	Behavioural Processes	Abbreviated Journal	Behav. Process.
	Volume	77	Issue	1	Pages	61-65
	Keywords	Gaze; Modification; Object-choice task; Raven
	Abstract	Most animals seem to have difficulties in using gaze cues to find hidden food in object-choice tasks. For instance, chimpanzees usually fail in these tests, even though they are capable of following other's gaze geometrically behind barriers. Similar to chimpanzees, common ravens are skilled in tracking other's gaze but fail in object-choice tasks. We here explored whether procedural modifications, which had been used successfully in chimpanzees, would also yield positive results in ravens. In our modifications (a) the experimenter approached the cup while gazing at it, (b) the gaze cue was accompanied by a sound and (c) the experimenter could actually see the food while giving the gaze cue. Two out of seven birds performed above chance level in some of these conditions. However, we ascribe this improvement to the individuals' learning ability rather than to an understanding of the communicative nature of the task. This interpretation is further supported by results of a follow-up experiment suggesting that ravens may not rely on conspecifics' gaze cues for finding food caches in a natural foraging context. In sum, our results suggest that ravens may not transfer their gaze follow abilities to foraging situations involving hidden food.
	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	4505
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	Author	Bílá, K.; Beránková, J.; Veselý, P.; Bugnyar, T.; Schwab, C.
	Title	Responses of urban crows to con- and hetero-specific alarm calls in predator and non-predator zoo enclosures			Type	Journal Article
	Year	2017	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	20	Issue	1	Pages	43-51
	Keywords
	Abstract	Urban animals and birds in particular are able to cope with diverse novel threats in a city environment such as avoiding novel, unfamiliar predators. Predator avoidance often includes alarm signals that can be used also by hetero-specifics, which is mainly the case in mixed-species flocks. It can also occur when species do not form flocks but co-occur together. In this study we tested whether urban crows use alarm calls of conspecifics and hetero-specifics (jackdaws, Corvus monedula) differently in a predator and a non-predator context with partly novel and unfamiliar zoo animal species. Birds were tested at the Tiergarten Schönbrunn in the city of Vienna by playing back con- and hetero-specific alarm calls and control stimuli (great tit song and no stimuli) at predator (wolf, polar bear) and non-predator (eland antelope and cranes, peccaries) enclosures. We recorded responses of crows as the percentage of birds flying away after hearing the playback (out of those present before the playback) and as the number of vocalizations given by the present birds. A significantly higher percentage of crows flew away after hearing either con- or hetero-specific alarm calls, but it did not significantly differ between the predator and the non-predator context. Crows treated jackdaw calls just as crow calls, indicating that they make proper use of hetero-specific alarm calls. Responding similarly in both contexts may suggest that the crows were uncertain about the threat a particular zoo animal represents and were generally cautious. In the predator context, however, a high percentage of crows also flew away upon hearing the great tit control song which suggests that they may still evaluate those species which occasionally killed crows as more dangerous and respond to any conspicuous sound.
	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	1435-9456	ISBN		Medium
	Area		Expedition		Conference
	Notes				Approved	no
	Call Number	Equine Behaviour @ team @ Bílá2017			Serial	6159
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	Author	Range, F.; Horn, L.; Bugnyar, T.; Gajdon, G.; Huber, L.
	Title	Social attention in keas, dogs, and human children			Type	Journal Article
	Year	2009	Publication	Animal Cognition	Abbreviated Journal	Anim. Cogn.
	Volume	12	Issue	1	Pages	181-192
	Keywords
	Abstract	Abstract: Understanding animals" abilities to cooperate with and learn from each other has been an active field of research in recent years. One important basis for all types of social interactions is the disposition of animals to pay attention to each other-a factor often neglected in discussions and experiments. Since attention differs between species as well as between individuals, it is likely to influence the amount and type of information different species and/or observers may extract from conspecifics in any given situation. Here, we carried out a standardized comparative study on attention towards a model demonstrating food-related behavior in keas, dogs and children. In a series of experimental sessions, individuals watched different conspecific models while searching, manipulating and feeding. Visual access to the demonstration was provided by two observation holes, which allowed us to determine exactly how often and for how long observers watched the model. We found profound differences in the factors that influence attention within as well as between the tested species. This study suggests that attention should be incorporated as an important variable when testing species in social situations.
	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	4713
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