Sökning: "Bird migration"

Visar resultat 16 - 20 av 39 avhandlingar innehållade orden Bird migration.

  1. 16. Avian migration: the role of geomagnetic cues

    Författare :Ian Henshaw; Cecilia Kullberg; Thomas Alerstam; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; geomagnetic cues; orientation; food intake; fuel deposition; corticosterone; endogenous time program; bird migration; Biology; Biologi; etologi; Ethology;

    Sammanfattning : The regularity and scale of bird migrations has impressed mankind for generations. Birds rely on an inherited migratory program to guide them during the journey; however, recent evidence suggests that additional external cues are necessary. LÄS MER

  3. 17. Nesting and migration in the introduced Canada goose in Sweden

    Författare :Göran Sjöberg; Catherine M. Lessells; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Species introductions; DNA fingerprinting; natal dispersal; breeding dispersal; bird migration; wintering areas; clutch size; laying date; body reserves; nest defence; waterfowl; Canada goose; Anatidae; Branta canadensis;

    Sammanfattning : The aim of the thesis was to document patterns in breeding and migration in Swedish Canada geese Branta canadensis, to explain these against the genetic and historical background of the population, and to test predictions of hypotheses pertaining to parental investment.The Canada goose population in Sweden was founded by the introduction of a few individuals in the 1930's. LÄS MER

  4. 18. Stopover behaviour in migratory songbirds: timing, orientation and departures

    Författare :Sissel Sjöberg; Funktionell zoologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; flight duration; orientation; departure timing; stopover behaviour; stopover duration; flight behaviour; reverse migration; route choice; compass calibration; passerines; Bird migration;

    Sammanfattning : Songbird migrants use stopovers between flight bouts to rest and refuel for the upcoming flights. Behaviours affecting where, when and how long to stay at stopover sites will affect how successful the overall migration will be, which has significant consequences for the overall fitness and mortality of the birds. LÄS MER

  5. 19. Time and energy in long-distance bird migration

    Författare :Thord Fransson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; zoologi; Zoology;

    Sammanfattning : Long-distance seasonal migration is energetically demanding and time consuming. For example, some passerine birds are on migration during six months of the year, travel more than 10 000 km and make use of many fuelling sites. Migration requires many different decisions, and an individual bird will face a variety of situations. LÄS MER

  7. 20. 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