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Druhově specifické hejnové chování ryb ve sladkovodní nádrži.
HOLUBOVÁ, Michaela
This study handles the problematics of schooling behaviour in the pelagic habitat of a temperate freshwater reservoir by the means of underwater visual survey via underwater camera. UVC proved to be a great tool for obtaining behavioural patterns which are rather poorly studied in the pelagic zone. Four species were identified as school forming. Naturally, schooling tendency varied in between species mostly due to proneness to predation, increasing with vulnerability to a predator. Heterospecific schools were quite common, particularly in vulnerable species sharing a space and food niche with species less attractive to predators.
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Pozorování hejnového chování ryb v pelagickém habitatu umělé vodní nádrže prostřednictvím videokamery
HOLUBOVÁ, Michaela
The research presented in this thesis contributes to broadening of the knowledge on free-living adult fish schools and behavioural patterns in a temperate freshwater reservoir. The behaviour of fish in the pelagic zone is rather poorly studied. Naturally, schooling tendency varied between species mostly due to increasing vulnerability to predation. Heterospecificity in schools was not a rare phenomenon, mainly for vulnerable species that shared the same space and food niche with a predatory less attractive species. The individual needs fluctuate as factors might be reconsidered in short time periods and most probably are reflected in behavioural responses. Individual responses are also reflected in the distribution of the fish in the reservoir and density in particular habitat. There is a "critical density" that triggers the formation of fish schools, followed by a slowing increase in density of fish clusters (observed units). This corresponds to increasing proportion of fish in a school and declining proportion of singletons. The trend of count of clusters tended to have an upper limit that should result in constant count of fish clusters after reaching a particular fish density. In other words, fish in the habitat maintain maximal distances even when the density increases. During high density periods the distances are kept by school formation. Overall the usage of the visual census as presented, proved to be a convenient tool for observation and assessment of freshwater fish. It has been demonstrated that the method can obtain comparable results to hydroacoustic survey amounts as well as purse seining.
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Predators and antipredator defence of Auchenorrhyncha (Hemiptera)
Zeman, Šimon ; Raška, Jan (advisor) ; Michalko, Radek (referee)
Auchenorrhyncha are one of the species-richest groups of hemimetabolous insects. They feed mostly on plant sap and play an important role in food webs of various ecosystems; for humans, they are important mainly as pests of several crops. Because of their occurrence in many habitats, they are often preyed upon by number of predators, including both vertebrates and invertebrates. However, Auchenorrhyncha implement various anti-predator defences to avoid it. This thesis summarizes available information about predation of Auchenorrhyncha and shortly deals with hunting behaviour of selected predators. In the second part, anti-predatory strategies and their occurrence in different Auchenorrhyncha groups are summarized. Furthermore, potential predators affected by those defences are discussed.
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Responses of naive primates to snakes: experiments with selected species kept in Prague zoo
Kutinová, Lucie ; Frynta, Daniel (advisor) ; Fuchs, Roman (referee)
In the wild, snakes are known to elicit strong antipredator responses in primates. Primates often mob the snakes, which is also accompanied by loud calls. In evolution, the deadly threat posed by snakes goes as far as to the origin of placental mammals. In this study, the reactions of naïve individuals to snakes were tested. Naïve pigtail macaques (Macaca nemestrina) and mouse lemurs (Microcebus murinus) avoided the snake stimulus. For the macaques there was a longer latency to touch the rubber snake compared to the latency to touch the rubber lizard. The mouse lemurs avoided feeding on the side of experimental box where the snake odor was presented. The reactions of macaques and mouse lemurs were not accompanied by vocalizations and they seemed to be overall mild. Nevertheless, the snake stimuli used here were strong enough for these naïve primates. For ringtail lemurs (Lemur catta), the reactions to uncovering a hidden rubber snake was tested. But the lemurs showed no avoiding reactions. A question for further research is whether the different results for lemurs were not caused by different experimental procedure. As well as in macaques and mouse lemurs, the reactions seemed to be very mild. But no deeper analysis of the behavior was performed. Thus, a reaction could have been overlooked, which...
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Antipredatory behaviour of Red-backed Shrike: the role of sign stimuli in a predator recognition
Součková, Tereza ; Fuchs, Roman (advisor) ; Hořák, David (referee)
This thesis summarizes findings on a recognition and categorization of different sorts of stimuli at birds, it deals with predator recognition in the Red-backed Shrike (Lanius collurio) in its practical part. The aim of my study was to examine if Red-backed Shrikes follow by sign stimuli or colour of stimulus during the predator recognition. I performed my research by means of experiments with dummies, I have observed antipredatory reactions of Red-backed Shrikes on various types of dummies which differ in the presence or absence of features of raptor or in the different coloration. I concluded according to Shrikes' reactions that during the predator recognition the information on sign stimuli playes the principal role, but only this information alone is not fully sufficient. Antipredatory behaviour of the Red-backed Shrike was also influenced by sex of bird apart from type of dummy, males were more active during the nest defence than females.
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Reakce krkavce velkého (\kur{Corvus} corax) na heterospecifické varovné hlasy
DAVÍDKOVÁ, Marika
The following work encompasses a research in the behaviour of the common raven (Corvus corax). I tested the responses of the common raven to heterospecific alarm calls of various bird species that differ in familiarity and taxonomical relatedness to ravens. Two other corvid species (jays) and two non-corvids (gulls) were presented. The ravens were given stimuli from one jay and one gull - one of which was always familiar to the tested ravens (European) and one unfamiliar (American). The results suggest that familiarity is not as important as the membership to the Corvidae family.
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Is the growth of brown frog`s tadpoles influenced by the presence of red-eared slides?
VODRÁŽKOVÁ, Magda
An increasing amount of attention is devoted to studying the impact of non-native animal species on native species. Among other causes of ecosystem degradation, such as climate change, polution and habitat conversion, biological invasion is considered as one of the main causes of the decrease in biological diversity all over the world. In order to detect possible predation event, tadpoles use not only visual and mechanical stimuli, but also chemical one. The tadpoles respond to the certain chemicals to be a part of predator's secretions. In aquatic systems, chemical cues are a major source of information through which animals are able to assess the current state of their environment to gain information about local predation risk. Prey use chemicals released by predators to mediate a range of behavioural, morphological and life-history antipredator defences. Tadpoles swim significatnly less and also on a less direct trajectory in the presence of chemical cues released by a turtle Trachemys scripta. This article is focused on the influence of mentioned constraints on the dynamics and the time dynamics of the larval growth of Rana temporaria. The influence was judged by the impact on the tadpole's development. We anticipated a behavioral response to the predator, which would lead to various growth reactions during larval growth, the resulting body size after metamorphosis, but also in the development time of larval stage. The results indicate that tadpoles of Rana temporaria changed behaviour in the presence of Trachemys scripta. Tadpoles in the permanent presence of the turtle grew faster, metamorphosed earlier and the resulting size after metamorphosis was smaller than of the tadpoles who developed without presence of the predator. Mentioned reactions may affect the survival and fitness of a metamorphosed individual.
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Antipredatory and exploratory behaviour as personality measure in Eublepharis macularius
Staňková, Jana ; Frynta, Daniel (advisor) ; Sedláček, František (referee)
This thesis "Antipredatory and exploratory behavior as an expression of personality in Leopard (Eublepharis macularius)" focuses on behavior Leopard gecko (Eublepharis macularius) in the exploratory and antipredation test. The aim is to determine whether some of the symptoms are characteristic of personality Leopard. The theoretical part will demonstrate the concept of personality. What are the terms for it to be about the phenomenon say that it is an expression of personality. We will deal with the various attempts used. The practical part will focus on the design of individual experiments and the results arising therefrom. Keywords: personality, repeatability, antipredator behavior, exploratory behavior
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Referential vocalization of primates
Rejlová, Markéta ; Nekovářová, Tereza (advisor) ; Petrásek, Tomáš (referee)
Some types of vocalization encode only the individual properties of vocalization individuals such as species, size, and its motivational state, but also inform about events and objects around. This vocalization is called "functional reference." Referential communication acoustically different from other kinds of vocalization, and is produced only in response to specific stimulus. Recipient responds to vocalizations indirect information in the same manner as if the present initiative. Aim of this work to summarize the current knowledge on the referential communication of primates, especially food and anti-predator type, including neurological mechanisms, gestures intermediate, referential signal and interspecies comparisons. Keywords: referential communication, vocalization, primates, anti-predator behavior, feeding behavior
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Antipredatory behaviour of Red-backed Shrike: the role of sign stimuli in a predator recognition
Součková, Tereza ; Fuchs, Roman (advisor) ; Hořák, David (referee)
This thesis summarizes findings on a recognition and categorization of different sorts of stimuli at birds, it deals with predator recognition in the Red-backed Shrike (Lanius collurio) in its practical part. The aim of my study was to examine if Red-backed Shrikes follow by sign stimuli or colour of stimulus during the predator recognition. I performed my research by means of experiments with dummies, I have observed antipredatory reactions of Red-backed Shrikes on various types of dummies which differ in the presence or absence of features of raptor or in the different coloration. I concluded according to Shrikes' reactions that during the predator recognition the information on sign stimuli playes the principal role, but only this information alone is not fully sufficient. Antipredatory behaviour of the Red-backed Shrike was also influenced by sex of bird apart from type of dummy, males were more active during the nest defence than females.
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