National Repository of Grey Literature 2 records found  Search took 0.02 seconds. 
Factors affecting behaviour of avian predators to hoverflies (Syrphidae) and their models (Aculeata)
Truhlářová, Marie ; Exnerová, Alice (advisor) ; Sedláček, František (referee)
Batesian mimicry is an antipredator strategy used by harmless species to mimic dangerous models by their appearance. The so-called imperfect mimics are a phenomenon within Batesian mimicry. It would be expected that Batesian mimics are selected to resemble the model as perfectly as possible. However, in some species the resemblance is very poor. The aim of this study was to test reaction of predators towards a textbook example of Batesian mimics with imperfect mimicry, i.e., hoverflies (Syrphidae) and to verify some of the hypotheses describing imperfect mimicry. We conducted two experiments in which the model predators were great tits (Parus major). The topic of the first experiment was the effect of diversity of models on categorization and generalization of hoverflies. Birds were divided into two groups, with the first group receiving high diversity of models (10 species of Hymenoptera) and second group receiving low diversity of models (2 species of Hymenoptera). There were two parts of this experiment. Categorization training when great tits learn to discriminate between two categories of prey, palatable and unpalatable and generalization test, when great tits generalized their experience from categorization training to novel prey. Palatable prey was represented by non-mimetic flies (Diptera),...
Category discrimination in avian predators: formation of natural categories of unpalatable prey
Zíková, Markéta ; Exnerová, Alice (advisor) ; Sedláček, František (referee)
Ability to categorize objects to classes and react to members of one class similarly is important for animals, for example to facilitate discrimination between palatable and unpalatable prey. Objects are typically categorized according to their common features. Birds mainly use visual perception and so their prey also signals its unpalatability visually, through aposematic coloration. We studied the ability of great tits (Parus major) to categorize prey into classes of palatable and unpalatable according to its appearance. Birds were divided to three experimental groups, each tested with different categories of prey. First group was trained to discriminate between aposematic species of true bugs (Heteroptera) and non-aposematic species from other insect taxa. Second group was trained to discriminate non-aposematic species of true bugs and species of other insect taxa and the third in discrimination of pseudocategories, consisting of randomly assigned stimuli from the first experimental group. Tested birds were wild-caught adults and naïve, hand-reared juveniles. Juveniles were tested only in first two experimental groups. All birds were first trained in discrimination between the two categories and then tested in a generalization test with new stimuli. Both adults and juveniles learned to...

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