Search for dissertations about: "alternative prey"

Showing result 1 - 5 of 29 swedish dissertations containing the words alternative prey.

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

    Author : Birger Hörnfeldt; S. Erlinge; Umeå universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; 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

  2. 2. Variation in age and size at maturation in two benthic crustaceans in the Gulf of Bothnia

    Author : Kjell Leonardsson; J. Ekman; Umeå universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Age at maturation; alternative prey; Bergmanris rule; cannibalism; growth; life-history theory; mortality; Mvoxocephalus quadricornis; poikilotherm; Pontoporeia affinis; population dynamics; risk- taking behaviour; Saduria entomon; size at maturation; temperature;

    Abstract : The thesis deals with variation in age and size at maturation in Saduria entomon and Pontoporeia affinis along a depth gradient in the Gulf of Bothnia, Sweden. I have analysed at what sizes and ages animals should mature in relation to growth and mortality conditions. READ MORE

  3. 3. Alternative Stable States in Size-Structured Communities : Patterns, Processes, and Mechanisms

    Author : Arne Schröder; Lennart Persson; André M. de Roos; Tim Benton; Umeå universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; biomass overcompensation; Chaoborus; emergent Allee effect; Heterandria formosa; juvenile recruitment bottlenecks; ontogenetic niche shifts; Poecilia reticulata; Biology; Biologi;

    Abstract : Alternative stable states have been, based on theoretical findings, predicted to be common in ecological systems. Empirical data from a number of laboratory and natural studies strongly suggest that alternative stable states also occur in real populations, communities and ecosystems. READ MORE

  4. 4. Predator-prey interactions of raptors in an arctic environment

    Author : Jesper Nyström; Anders Angerbjörn; A. Rolf Ims; Stockholms universitet; []
    Keywords : NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Ecology of raptors; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Abstract : This thesis concerns the predator-prey interactions of three raptor species in a Swedish arctic community: the gyrfalcon (Falco rusticolus), the rough-legged buzzard (Buteo lagopus) and the golden eagle (Aquila chrysaetos). The gyrfalcon behaved like a highly specialised ptarmigan (Lagopus spp.) predator. READ MORE

  5. 5. Baltic cod predation: mechanisms, impact on prey, implications for fisheries

    Author : Nataliia Kulatska; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []

    Abstract : Trophic interactions are fundamental in the functioning of ecosystems. Predator-prey interactions between cod (Gadus morhua), herring (Clupea harengus) and sprat (Sprattus sprattus) in the Baltic Sea are typical examples of strong trophic interactions with consequences on the structure of this ecosystem. READ MORE