Sökning: "Raptors"

Visar resultat 1 - 5 av 10 avhandlingar innehållade ordet Raptors.

  1. 1. 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

  3. 2. 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

  4. 3. Spatial Vision in Birds: Anatomical investigation of spatial resolving power

    Författare :Mindaugas Mitkus; Funktionell zoologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Raptors; Seabirds; Parrots; Birds; Double cones; Development; Retinal ganglion cells; Visual spatial resolution; Visual ecology; Vision;

    Sammanfattning : Avian eyes are big both in relative and absolute terms, thus the importance of vision to birds is obvious. Even though the general eye plan is rather conservative throughout the group, there is a great variation in visual capabilities. LÄS MER

  5. 4. Conservation Genetics of the White-Tailed Eagle

    Författare :Frank Hailer; Hans Ellegren; Carles Vilà; Rob C Fleischer; Uppsala universitet; []
    Nyckelord :Biology; Haliaeetus albicilla; microsatellites; mtDNA; molecular sexing; population structure; bottleneck; phylogeography; raptors; Biologi;

    Sammanfattning : The white-tailed eagle is a formerly threatened raptor that is commonly used as a flagship and indicator species in conservation work. This thesis uses molecular genetic methods to study sex determination of nestlings, genetic variability, population structure and phylogeography of the white-tailed eagle. LÄS MER

  7. 5. Predator responses to non-stationary rodent cycles

    Författare :Peter Hellström; Anders Angerbjörn; Xavier Lambin; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Buteo lagopus; Vulpes lagopus; Lemmus; Myodes; population cycles; predation; numerical response; functional response; arctic; lemmings; voles; fox; monitoring; raptors; zoologisk ekologi; Animal Ecology;

    Sammanfattning : Regular fluctuations in population size, cycles, are common in small mammals and have important effects on predator populations and life histories. In this thesis, I identify long-term patterns and processes in two specialist predators, the arctic fox Vulpes lagopus and the rough-legged buzzard Buteo lagopus, in relation to their prey (lemmings and voles) and in the case of the arctic fox also to a dominant competitor, the red fox Vulpes vulpes. LÄS MER