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The effect of a predator occurrence on vigilance of tits visiting the winter feeder
Tichá, Irena ; Fuchs, Roman (advisor) ; Sedláček, Ondřej (referee)
This thesis evaluates the vigilance parameters of two species of tits affected by the presence of a predator in wintertime. During preferential experiments, tits have had a choice of two feeders in the vicinity of the installed dummy predator. For that purpose was used a dummy sparrowhawk, incomplete or occluded sparrowhawk torsos, and harmless pigeon. It is known that the tits are able to recognize dangerousness presented by the dummy, and according to expected risk dare to visit one of the feeders. It leads to a question whether the tits are somehow influenced by the presence of the dummies, and if so, how specifically are they influenced. It turned out, that the tits in presence of a dangerous dummy significantly increased their vigilance. Both observed species at the feeders behave oppositely. Behaviour of all the birds at the feeder is also affected by their total count at the precise moment and by the presence of a dummy at the other feeder.
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The use of amodal completion inpredators recognition: effect on risk taking
Sedláčková, Kristýna ; Fuchs, Roman (advisor) ; Nekovářová, Tereza (referee)
Amodal completion enables animals (birds, mammals, but also fish) to perceive partly occluded objects as whole. Most of the studies focusing on the occlusion phenomenon were carried out in a laboratory and were based on either operant conditioning or filial imprinting techniques. This study concentrates on behavior of untrained animals in their natural habitat. Pairwise preferential experiments were used to reveal responses of tits (the great tit, Parus major; the blue tit, Cyanistes caeruleus; the marsh tit, Poecile palustris) to two dummies placed near an experimental and an alternative feeder. The dummies used were the complete dummy of a sparrowhawk and a pigeon, and partly occluded (the lower or upper torso hidden in shrubs) and amputated (only lower or upper torso on the perch) models of sparrowhawks - 15 combinations altogether. The tits considered all variants of torsos to be predators. The great tit and the blue tit perceived the model with occluded lower torso as more dangerous than the one with amputated lower torso. Such discrimination between these torsos requires the ability of amodal completion. The great tit also confirms this ability as it regarded the complete sparrowhawk and the model with occluded lower torso as equally dangerous. In the remaining cases, the number of arrivals...
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Role znaků a geonů v rozpoznávání predátorů netrénovanými ptáky: obrana hnízda
NOVÁKOVÁ, Nela
I examined two main hypotheses proposed for the object recognition: Particulate feature theory and recognition by components using methods of behavioural ecology, namely nest defence. We tested reactions of Red-backed shrike (Lanius collurio) to dummies of Common kestrel (Falco tinnunculus) with scrambled body parts (head above, in the middle and at the bottom). Our result suggested that birds don't recognize the kestrel in the dummies with inappropriately placed head. Therefore, our results support rather the theory recognition by components.
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Role of features and geons in predator recognition by untrained birds: the feeder experiments
NOVÁKOVÁ, Nela
The mechanism of predator recognition in birds hasn't been understood well yet. There are two main hypotheses: recognition by components and particulate feature theory. We examined these theories in two-feeder experiment under natural conditions on wild untrained birds. We tested reactions of great tit (Parus major), blue tit (Cyanistes caeruleus), marsh tit (Poecile palustris), willow tit (Poecile montanus) and Eurasian nuthatch (Sitta europaea) to dummies of scrambled sparrow hawk (Accipiter nisus) compared to control complete sparrow hawk and pigeon (Columba livia f. domestica). Our results suggested that birds assesss all scrambled dummies equally as a real unscrambled sparrowhawk. Therefore our results support rather the particulate feature theory.
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The effect of coloration of predator on reaction of birds at the feeder.
BURŠÍKOVÁ, Markéta
I investigate the effect of coloration of predator on the willingness of birds to undergo a predation risk at the winter feeder. I presented five colour modification of a sparowhawk and a control pigeon. The experimental species of birds presented at the feeder include great, blue, marsch and willow tits and nuthatch. My results suggest that birds are able to distinguish among the models but only in some extent. The behaviour of particular bird species differed significantly and was influenced by conditions like temperature and presence of the snow cover.
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Pigeon with sparrowhawk head: friend or enemy?
NÁCAROVÁ, Jana
The mechanism of predator recognition hasn´t been understood well yet. There are two main theoretic attitudes to this problem. Feature theory claims that animals use only some key features of the stimuli for categorization. The other opinion is that animals have a general concept how the predator should look like and local features aren't so important. We examined these theories under labor conditions. We tested the reaction of great tit (Parus major) on wooded dummies of the sparrowhawk (Accipiter nisus), pigeon (Columba livia f. domesticus) and chimeras between them that differed in the type of head. Our results show, that great tits probably use combination of both approaches to recognize the predator.
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How do the birds recognize predators - importance of complete visual information
TVARDÍKOVÁ, Kateřina
Pair-wise preferential experiments were used to reveal dangerous predator differentiation and ability of amodal completion by four tit species. Firstly was revealed that the tits{\crq} behaviour towards the feeder was in agreement with predictions of the dynamic risk assessment theory. The presence of any predator at the feeder lowered the number of visits to the feeder. Likewise, the tits evaluated the sparrowhawk as more dangerous than the kestrel because its presence lowered the number of visits more than the kestrel. Secondly, we observed tits{\crq} reactions to both partly occluded and amputated dummy of sparrowhawk in two different treatments (torsos vs. complete dummy of pigeon, torsos vs. complete dummy of sparrowhawk). All birds clearly classified both torsos as ``full-featured{\crqq} predators and kept away of them when pigeon on the second feeder. However, when sparrowhawk was presented on the second feeder, number of visits to amputated predator was higher than to occluded one. Birds risked arriving to ``utter{\crqq} amputated torso while the fear of ``full-featured{\crqq} occluded torso stayed without change when second feeder did not provide safe alternative. Such discrimination between torsos needs ability of amodal completion.
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