Sökning: "Ecology of raptors"

Visar resultat 1 - 5 av 8 avhandlingar innehållade orden Ecology of raptors.

  1. 1. Plumage Colours and the Eye of the Beholder : The Ecology of Colour and its Perception in Birds

    Författare :Olle Håstad; Mats Björklund; Innes Cuthill; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; ultraviolet; colour vision; opsin; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Sammanfattning : Virtually all diurnal birds have tetrachomatic vision based on four different colour receptors. As a result, birds are potentially able to perceive their environment in twice as many colours as humans and four times as many colours compared to most other mammals, which are dichromatic. LÄS MER

  3. 2. Predator-prey interactions of raptors in an arctic environment

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

    Sammanfattning : 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. LÄS MER

  4. 3. Predators in low arctic tundra and their impact on community structure and dynamics

    Författare :Maano Aunapuu; Tarja Oksanen; Ola Atlegrim; Oswald J. Schmitz; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; arthropods; coexistence; community dynamics; competition; food webs; hypothesis of exploitation ecosystems; intraguild predation; small mustelids; trophic cascades; Ekologi; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi; zooekologi; Animal Ecology;

    Sammanfattning : The abundance of predators and their impact on ecosystem dynamics is a vividly discussed topic in current ecology. In my studies, incorporating field observations, field experiments and theoretical modeling, I explored the importance of predators and predation in a low arctic tundra ecosystem in northern Norway. LÄS MER

  5. 4. Migration strategies of raptors – spatio-temporal adaptations and constraints in travelling and foraging

    Författare :Roine Strandberg; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; route convergence; loop migration; mortality; spatio-temporal distribution patterns; pre- and post-migratory movements; daily travel routines; satellite tracking; fly-and-forage migration; raptors;

    Sammanfattning : My dissertation is about bird migration and addresses questions about how raptors adapt to the fluctuating environments during the transition seasons between breeding and wintering. The migration is highly affected by local prey abundance, foraging strategies, weather conditions and landscape patterns along the migration routes as well as navigation and orientation mechanisms and cues. LÄS MER

  7. 5. Differential migration in raptors

    Författare :Nils Kjellén; Biodiversitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Osprey; Skua; Population monitoring; Bird migration; Satellite telemetry; Animal ecology; Djurekologi;

    Sammanfattning : Differences between ages, sexes and populations in the timing of migration at Falsterbo, Sweden and in the choice of wintering site among raptors in Scania were investigated. Competition and dominance is the best primary explanation to the results. LÄS MER