Search for dissertations about: "Seasonality"

Showing result 16 - 20 of 107 swedish dissertations containing the word Seasonality.

2. 16. Cycles of voles, predators, and alternative prey in boreal Sweden

   Author : Birger Hörnfeldt; S. Erlinge; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; 3-4 year cycles; Clethrionomys glareolus; Clethrionomys rufocanus; Microtus agrestis; snap-trapping; rate of change; population regulation; delayed density-dependence; time-lag mechanism; seasonality; predation; food; predator avoidance; foraging behaviour; Aegolius funereus; nest boxes; numerical response; nomadism; Vulpes vulpes; Sarcoptes scabiei vulpes; Lepus timidus; Francisella tularensis; Tetraonidae; hunting statistics; zooekologi; Animal Ecology;

   Abstract : Bank voles, grey-sided voles, and field voles had synchronous 3-4 year density cycles with variable amplitudes which averaged about 200-fold in each species. Cycles of vole predators (red fox and Tengmalm's owl), and their (foxes') alternative prey (mountain hare and forest grouse) lagged behind the vole cycles. READ MORE

4. 17. Bacterioplankton population dynamics in a changing ocean

   Author : Markus V. Lindh; Jarone Pinhassi; Pierre Galand; Linnéuniversitetet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; marine microbiology; ecology; bacterioplankton; community composition; diversity; seasonality; biogeography; bimodal; metapopulation; community functioning; climate change; environmental disturbance;

   Abstract : Bacterioplankton is characterized by high diversity, short generation times and rapid turnover. Despite their small size, these numerous microorganisms are a fundamental piece of aquatic ecosystems by channeling carbon to higher trophic levels through dissolved organic matter utilization. READ MORE

5. 18. Host-seeking activity of Ixodes ricinus in relation to the epidemiology of Lyme borreliosis in Sweden

   Author : Hans Mejlon; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; Borrelia burgdorferi; control; Ixodes ricinus; Lyme borreliosis; seasonality; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; Entomology; entomologi;

   Abstract : This thesis examines seasonal, diel and vertical distribution patterns of activity of host-seeking Ixodes ricinus (L.) ticks at three localities in south-central Sweden. In addition, by examining the prevalence of infection in ticks with Lyme borreliosis (LB) spirochetes, Borrelia burgdorferi s. READ MORE

6. 19. Costs of foraging in a dry tropical environment

   Author : Mary Molokwu; Biologiska institutionen; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; foraging behavior; seasonality; predation risk; granivorous birds; food availability; water; temperature; savannah; dry tropics; energy; secondary compounds; diet selection;

   Abstract : This study evaluates the costs associated with foraging for birds in a savannah woodland area in central Nigeria. Specifically, it looks at the following questions: 1) how does seasonal variability in food and water availability affect the value of resources to birds in dry environments? 2) Does proximity to water affect foraging decisions? What implication will this have in the management of savannah birds? 3) Are tropical birds mostly affected by metabolic or predation costs? 4) What factors affect diet selection in birds and how? 5) How are birds adapted to hot dry environments? I carried out experiments in the field and in an aviary and provided artificial food patches, consisting of feeding trays with seeds mixed in sand or pebbles (in the aviary study). READ MORE

7. 20. Movement ecology of aerial insectivorous birds : Individual-based studies on swifts and nightjars

   Author : Gabriel Norevik; Evolutionär ekologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; swift; nightjar; Apus; Caprimulgus; tracking; archival tags; GPS; geolocation; multi-sensor logger; migration; continuous flight; route choice; altitude; lunar cycle; seasonality;

   Abstract : Many birds are predisposed to annually undertake movements over large temporal and spatial scales. They have an efficient flight machinery, demonstrate impressive capacities in storing and burning fuel, and they exhibit necessary orientation and navigational skills. READ MORE