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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 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 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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