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Nest defence and predator recognition by Arctic tern \kur{(Sterna paradisaea)}
ŠPIČKA, Jan
In the presented work, I describe the behaviour of Arctic terns (Sterna paradisaea) toward predator species that differ in the threat they represent to them and to their nests. I presented textile dummies of great black-backed gull (Larus marinus), peregrine falcon (Falco peregrinus), common raven (Corvus corax) and common eider (Somateria mollissima), piece of wood as a harmless stimulus, and human intruder in sitting position near the tern nests. Experiments were conducted on the Varanger peninsula in Norway. The tern behaviour was recorded and analysed to see any dummy species related differences.
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Rozpoznávání predátorů strakou obecnou (Pica pica)
ŠPIČKA, Jan
In the presented work, I describe the ability of Eurasian Magpie (Pica pica) to recognize predator species differing in the threat they represent. I presented stuffed dummies of northern goshawk (Accipiter gentilis, juvenile and adult female), common buzzard (Buteo buteo), common raven (Corvus corax) and common pheasant (Phasianus colchicus) to magpie pairs within the area of České Budějovice. The magpie behaviour was recorded and analysed, to see any dummy species related differences.
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The role of the face and the body size in predators' recognition by untrained birds
Fišer, Ondřej ; Fuchs, Roman (advisor) ; Petrusková, Tereza (referee)
The face plays an extremely important role in human communication. It enables individual recognition and provides other information about the person, such as social or emotional information. Human psychology has shown that face recognition uses a specific cognitive process called holistic processing. In recent decades, it has been shown to play an important role in animal communication as well. In the first part of my thesis, I tested whether changing the uniform configuration of a bird's face would affect the ability of the red-backed shrike (Lanius collurio) to recognize a potential predator. Due to unfavourable conditions in both breeding seasons when the experiments were conducted, no firm conclusions can be drawn from the results. They only suggest that the shrike perceives the configuration changes. An essential characteristic of all predators is their size, which affects the ability of prey to defend themselves. Several studies have already found that birds discriminate between different predators of different sizes. In the second part of my thesis, I evaluated experiments in which shrikes were exposed to dummies of two predator species with modified size. The shrikes responded with less aggression to the enlarged jays, whereas aggression increased only slightly to the shrunken crows. Thus,...
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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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How do the birds recognize the 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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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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