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The importance of water sources for space-use of mammals in African savannah
Homoláč, David ; Hořák, David (advisor) ; Brandlová, Karolína (referee)
African savannas are seasonal ecosystems experiencing a significant dry period each year. During the dry season, water scarcity has both, spatial and temporal consequences on the movements of large mammals. Some mammals can cope with these resource restrictions better than others. These water independent mammals predominantly feed on browse (giraffe, kudu, eland) and can be found further from water sources. However, these mammals can utilize areas near rivers as these areas provide food resources. Water dependent species are predominantly grazers and non-ruminants (zebra, wildebeest, elephant). Water shortage during a dry season restricts the movements of these species, which can be generally found in the vicinity of water bodies. Carnivore species (lions) react on the spatial restrictions of ungulates by adjusting their hunting areas to the vicinity of water sources. Both intra-guild (African wild dog) and inter-gild prey species (ungulates) develop anti-predatory strategies such as temporal and spatial segregation. African wild dogs use dens far from water points and ungulate species use to drink during daytime when lions are not active. Spatial and temporal segregation are also strategies to cope with competitors. Daily patterns of water point visitations can vary suggesting other factors...
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Habitat specific population densities in animals: a concept review
Šlosarová, Dita Afrodita ; Hořák, David (advisor) ; Koleček, Jaroslav (referee)
Population density estimate can be expressed through many different ways. Various concepts differ above all in area of the survey, which is influenced by aim of the research and the purpose of the results. Commonly used crude density reports the abundance of individuals per unit of a geographic space. Ecological population density concept, on the other hand, expresses the number of individuals within an ecological space, such as specific habitat type, hence the usage of habitat-specific name as well. Ecological density in comparison to crude density, often shows considerably higher population density. It it clear that higher values of ecological density appear to be caused either by smaller area of the survey or by selection of the area by prior knowledge of space distribution of individuals Although some authors like Elton, Mohr and Damuth attempted to define different concepts, there is still no united and strict definition of ecological density. Therefore, we meet with many variations and a broad scope of utilization, that are all collectively named ecological or habitat specific density. While using the habitat-specific density it is crucial to consider many aspects such as the body mass of the individuals, which correlates to size of the area of occurrence, their habitat preferences and...
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